SEO Takehiko

Researcher Information

Degree

• Master（Osaka University）

Research funding number

• 00432526

J-Global ID

• 200901090358940134

Research Interests

• Combustion, Ignition   流体   燃焼   熱   Fluidics   Combustion   Thermal engineering   

Research Areas

• Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Thermal engineering
• Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Fluid engineering

Academic & Professional Experience

• 2022/04 - Today  Kindai University理工学部機械工学科准教授
• 2016/04 - 2022/03  山口大学大学院創成科学研究科准教授
• 2014/01 - 2016/03  山口大学大学院理工学研究科准教授
• 2010/02 - 2011/06  YAMAGUCHI UNIVERSITYGraduate School of Science and Engineering(Engineering)Assistant Professor
• 2008/05 - 2009/09  Tokyo Institute of TechnologyGraduate School of Science and Engineering, Department of Mechanical and Aerospace Engineering特任助教
• 2007/04 - 2008/04  Osaka UniversityGraduate School of Engineering, Division of Mechanical Engineering特任研究員
• 2007/04 - 2008/04  Osaka UniversityGraduate School of Engineering, Division of Mechanical Engineering
• 2006/04 - 2007/03  Osaka UniversityGraduate School of Engineering, Division of Mechanical Engineering特任助手
• 2006/04 - 2007/03  Osaka UniversityGraduate School of Engineering, Division of Mechanical Engineering
• 2006/01 - 2006/03  Osaka UniversityGraduate School of Engineering, Division of Mechanical Engineering
• Former Institution / Organization Tokyo Institute of Technology Graduate School of Science and Engineering Department of Mechanical and Aerospace EngineeringAssistant Professor

Education

•        - 2006/03  Osaka University  Graduate School, Division of Engineering  Mechanical Science and Engineering
•        - 2006  Osaka University  工学研究科  機械物理工学
•        - 2003  Osaka University  工学研究科  機械物理工学
•        - 2003  Osaka University  Graduate School, Division of Engineering  Mechanophysics Engineering
•        - 2000/03  Osaka Prefecture University  Faculty of Engineering  Department of Aerospace Engineering
•        - 2000  Osaka Prefecture University  School of Engineering  Department of Aerospace Engineering
•        - 2000  Osaka Prefecture University  Faculty of Engineering  Aerospace Engineering

Association Memberships

• 日本燃焼学会   日本機械学会   The Combustion Institute   自動車技術会   日本液体微粒化学会   

Published Papers

• Effects of two-droplet interaction on the group combustion excitation in randomly distributed droplet clouds using a percolation model

  Yuka Hara; Yuto Chikami; Takehiko Seo; Masato Mikami

  Proceedings of the 13th Asia-Pacific Conference on Combustion M6-11  2021/12 [Refereed]
  
• Study on two-stage ignition of two interactive droplets in flame spread over n-decane droplets in microgravity

  Yuto CHIKAMI; Kodai MATSUMOTO; Takehiko SEO; Masato MIKAMI

  Proceedings of 15th International Conference of Liquid Atomization and Spray Systems 1 (1) Paper 141  2021/08 [Refereed]
  
• A study of the effect of swirling airflow on fuel spray characteristics under low pressure atmosphere

  Kenichi Shimizu; Takehiko Seo; Masato Mikami

  International Conference on Liquid Atomization and Spray Systems (ICLASS) Edinburgh University Library 1 (1) 2021/08 [Refereed]
  
• A study on the effect of combustion impact on radiated noise characteristics and exhaust emission characteristics of a single cylinder diesel engine

  IMOTO Daiki; OGUCHI Hitoshi; SEO Takehiko; MIKAMI Masato

  The Proceedings of Mechanical Engineering Congress, Japan The Japan Society of Mechanical Engineers 2020 J07111  2020 

  Diesel engines are widely used. However, they have issues of large emissions of nitrogen oxide and soot and high combustion noise. In order to improve understanding of the relationship between combustion noise and exhaust emission under various combustion conditions, this study investigates the effects of combustion impact on radiated combustion noise and exhaust emission characteristics for a single-cylinder diesel engine with a supercharger and EGR system by changing the fuel injection conditions, intake air pressure and oxygen concentration in the intake air. The results show that the engine noise greatly depends on the maximum combustion impact energy at 2500 Hz. As the maximum combustion impact energy is increased, NOx emission roughly increases, smoke emission roughly decreases, and CO emission roughly stays constant. However, there are some operating parameters which show different dependencies.
• Study of laminar flame speed measurement under high pressure condition using double kernel method by laser-induced breakdown ignition

  Takehiko Seo; Hirotsugu Kaneko; Masato Mikami

  JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY JAPAN SOC MECHANICAL ENGINEERS 15 (3) 1880-5566 2020 [Refereed]
   

  In order to understand turbulent combustion and its combustion characteristics, laminar flame speed is often used. Laminar flame speed plays an important role in turbulent combustion models used in engine combustion simulation. However, there are few reports on laminar flame speed of liquid fuel under high pressure condition simulating the inside of an engine cylinder. In this study, the measuring system using simple compact equipment was developed to obtain laminar flame speed of liquid fuel with the double kernel method under high pressure conditions. In this equipment, as easily ignited at high pressure, laser induced breakdown ignition technique was used. The experiments were conducted on propane-air premixed gas so that it could be easily compared with the reports of other researchers. The experiment was conducted on propane/air premixture so that it could be easily compared with the other reports. A detailed investigation of the time history of the flame separation revealed that the conventional method of calculating the laminar flame speed used in the double kernel method was not suitable for this measuring system. Therefore, a new calculation method for the laminar flame speed was studied, and the pressure dependence of the laminar flame speed of the propane/air premixture was investigated. As a result, it was found that it was in good agreement with other reports. The laminar flame speed measurement system developed in this study is considered to be useful.
• Combustion of n-Octane/ethanol Mixture in a Meso-scale Combusotr using Electrospyra Technique

  Cheng YOU; Takatoshi KUWATA; Takehiko SEO; Masato MIKAMI

  Proceedings of the 20th Annual Conference on Liquid Atomization and Spray Systems - Asia ILASS-Asia2019-072  2019/12 [Refereed]
  
• Study on Flame Spread Behavior in Two-dimensional and Three-dimensional Droplet Clouds Considering Flame-spread limit Based on Microgravity Experiments of Flame Spread of Droplet Arrays

  Saputro, H; Mikami, M; Seo, T

  Proceedings of 12th Asia-Pacific Conference on Combustion ASPACC2019-1488  2019/07 [Refereed]
  
• The Influence of Connecting-Rod Specifications on the Combustion-Noise Generation from a Diesel Engine

  Oguchi, H; Minato, K; Seo, T; Mikami, M

  SAE Technical Paper SAE International 2019-01-1590  2019/06 [Refereed]
  
• Flame-spread limit from interactive burning droplets in microgravity

  Yasuko Yoshida; Kentaro Iwai; Kentaro Nagata; Takehiko Seo; Masato Mikami; Osamu Moriue; Tetsuya Sakashita; Masao Kikuchi; Takuma Suzuki; Masaki Nokura

  PROCEEDINGS OF THE COMBUSTION INSTITUTE ELSEVIER SCIENCE INC 37 (3) 3409 - 3416 1540-7489 2019 [Refereed]
   

  This research conducted microgravity experiments on the flame spread over droplet-cloud elements with strong droplet interaction aboard Kibo on the ISS. The droplet-cloud element represents a local droplet pattern appearing in randomly distributed droplet clouds near the group-combustion-excitation limit and consists of small-droplet-spacing droplets and large-droplet-spacing droplets. As droplet-cloud elements, we used four n-decane droplets, Droplets C, B, A and L, placed at fiber intersections of two-dimensional SiC-fiber lattice with a 4-mm fiber interval in a combustion chamber. The flame spreads over the droplet-cloud element in order of Droplets C, B, A and L. The position of Droplet L relative to Droplet A was varied to investigate the flame-spread-limit distribution around burning Droplet A. The position of Droplet B relative to Droplet A was varied to investigate the effect of two-droplet interaction between Droplets B and A on the flame spread to Droplet L. The position of Droplet C relative to Droplet B was also varied to investigate the effect of three-droplet interaction among Droplets C, B and A. The results shows that in the case with the strong interaction by two or three interactive droplets, the high-temperature region is enlarged by the droplet interaction, centers near the center of mass of the interactive droplets and plays an important role in the flame-spread-limit distribution. Since the burning lifetime of Droplet A is finite, the flame-spread time from burning Droplet A to Droplet L is limited by burning lifetime of Droplet A and is less than 80% of the burning lifetime of Droplet A, which increases with the interactive effect. The flame-spread-limit distance from the center of mass of the interactive droplets increases with the burning lifetime. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
• A Study on the Influence of Connecting-Rod Specification and Fuel-Injection Timing on Radiated Noise Characteristics of a Diesel Engine

  Oguchi Hitoshi; Minato Koki; Sumida Yoshiki; Seo Takehiko; Mikami Masato

  Transactions of Society of Automotive Engineers of Japan Society of Automotive Engineers of Japan 50 (2) 285 - 290 0287-8321 2019 [Refereed]
   

  By shifting natural frequencies of the internal transmission system of combustion impact power in a diesel engine and by changing the fuelinjection timings in the case with two-stage combustion, we made a natural frequency of the internal transmission system coincided with a combustion-impact cancelling frequency and investigated the influence of the present method on the radiated noise characteristics. We confirmed that we can make the natural frequency of the piston-connecting rod vibration higher and reduce the engine noise by shortening thinned portion of connecting rod. We also confirmed that the combination of changing the natural frequency of the piston-connecting rod vibration and noise cancelling spike combustion is effective in the engine noise reduction.
• A Study of Laser-induced Breakdown Ignition in Fuel Spray (2^nd Report: Investigation of Laser-induced Breakdown and Ignition Characteristics in Fuel Spray Flow)

  SEO Takehiko; ISHIMURA Yuki; MIKAMI Masato

  Journal of the Combustion Society of Japan Combustion Society of Japan 61 (196) 142 - 148 1347-1864 2019 [Refereed]
   

  In order to ignite fuel spray directly by a laser beam, it is necessary to investigate the characteristics of laser-induced breakdown ignition and generation of plasma as ignition sources in fuel spray. This study conducted experiments of laser-induced breakdown ignition in an steady ethanol/air premixture and ethanol spray flow by using third harmonic of the Q-switched Nd:YAG laser. For evaluation of breakdown occurrence and ignition probability, the flame and the plasma images were obtained. And laser beam incident energy was also measured. Although probability of the breakdown occurrence and the ignition increased with the increase of incident energy, there are great difference between the breakdown threshold and the minimum ignition energy in the case of spray flow. Also, in spray flow, plasma was generated at multiple points and its number, size and position are different from pulse to pulse. The initial flame kernels generated by these plasmas were growing while being affected by each other. It is suggested that the behavior of the fuel droplets around the initial flame kernel affect the ignition probability since the ignition probability with increasing number density of droplets is decreased.

• Recent Accomplishment of "Group Combustion" Experiments aboard Kibo on ISS

  Masato Mikami; Yasuko Yoshida; Takehiko Seo; Osamu Moriue; Tetsuya Sakashita; Masao Kikuchi; Yuji Kan

  INTERNATIONAL JOURNAL OF MICROGRAVITY SCIENCE AND APPLICATION JAPAN SOC MICROGRAVITY APPLICATION 36 (3) 360301  0915-3616 2019 [Refereed]
   

  The first microgravity combustion experiments were conducted in 2017 aboard the Japanese Experiment Module "Kibo" on ISS, titled "Elucidation of Flame Spread and Group Combustion Excitation Mechanism of Randomly Distributed Droplet Clouds (Group Combustion)." The objective of this experiment is to study the effects of droplet interaction, radiative heat loss from a flame, and droplet motion during flame spread. This report describes some recent accomplishments from the "Group Combustion" experiments with droplet-cloud elements to study the effects of droplet interaction and randomly distributed droplet clouds with about 100 droplets to study the macroscopic characteristics of flame spread and local flame spread characteristics. Two types of anomalous behavior observed near the group-combustion-excitation limit are also reported, which had not been expected from parabolic flight experiments and percolation calculations to express the group-combustion excitation through flame spread over droplets.
• Temperature-Field Analysis of Flame Spread over Droplet-Cloud Elements with Interactive Droplets in Microgravity aboard Kibo on ISS

  Yasuko Yoshida; Takehiko Seo; Masato Mikami; Masao Kikuchi

  INTERNATIONAL JOURNAL OF MICROGRAVITY SCIENCE AND APPLICATION JAPAN SOC MICROGRAVITY APPLICATION 36 (3) 360303  0915-3616 2019 [Refereed]
   

  Liquid-fuel combustion experiments titled "Elucidation of Flame Spread and Group Combustion Excitation Mechanism of Randomly Distributed Droplet Clouds (Group Combustion)" were conducted in 2017 as the first of the combustion experiments in the Japanese Experimental Module "Kibo" aboard the International Space Station (ISS). This paper reports temperature-field analysis by the TFP method based on visible light emissions for the flame spread of droplet-cloud elements composed of four droplets with two or three interactive droplets, which was conducted as part of the " Group Combustion" experiments. The results show that the position of the interactive droplets affects the flame spread around the droplets, and the flame-spread limit is extended by the interactive effect. If a burning droplet pre-heats a droplet existing outside the flame-spread limit, the pre-vaporization also extends the flame-spread limit around two interactive droplets.
• A Study of Flame Spread of n-Decane Droplet Arrays with Fuel-vapor Jet at High Pressures in Microgravity

  R. Uneyama; K. Iwai; K. Nagata; Y. Yoshida; T. Seo; M. Mikami

  Proceedings of The 7th Joint Conference on Renewable Energy and Nanotechnology EL08  2018/12 [Refereed]
  
• A study on minimum ignition energy of n-heptane/air premixture with laser-induced breakdown ignition

  Yusuke ASAHI; Takehiko SEO; Masato MIKAMI

  Proceedings of The 7th Joint Conference on Renewable Energy and Nanotechnology IN05  2018/12 [Refereed]
  
• Flame-spread characteristics of droplet-cloud element with two-droplet interaction at high pressure in microgravity

  Kentaro Iwai; Yasuko Yoshida; Naoya Motomatsu; Takehiko Seo; Masato Mikami

  Transactions of JSASS, Aerospace Technology Japan 16 (6) 494 - 499 2018/09 [Refereed]
  
• Space-Based Microgravity Experiments on Flame Spread over Randomly Distributed n-Decane-Droplet Clouds: Overall Flame-Spread Characteristics

  Masato Mikami; Yasuko Yoshida; Takehiko Seo; Tetsuya Sakashita; Masao Kikuchi; Takunna Suzuki; Masaki Nokura

  MICROGRAVITY SCIENCE AND TECHNOLOGY SPRINGER 30 (4) 535 - 542 0938-0108 2018/08 [Refereed]
   

  This research conducted microgravity experiments on the flame spread over randomly distributed n-decane-droplet clouds aboard the Japanese Experiment Module "Kibo" on the International Space Station. 67-152 droplets were distributed at intersections of a 30 x 30 square lattice with 14-micron SiC fibers placed in a combustion chamber. One droplet on the bottom side of lattice was ignited by a hot-wire igniter to start the flame spread. The burning behavior was observed by a digital camera. This paper is the first to report the group-combustion excitation of randomly distributed droplet clouds through flame spread and its dependence on the mean droplet spacing of the droplet cloud. The results show that there exists the group-combustion-excitation-limit mean droplet spacing. The flame-spread behavior is significantly affected by the initial conditions around the group-combustion-excitation limit, where the burning lifetime of the droplet cloud attains maximum and an interesting phenomenon, such as large-scale ignition, occurs. The group-combustion-excitation-limit mean droplet spacing is greater than the flame-spread-limit droplet spacing of the linear droplet array. The overall flame-spread rate of the droplet cloud is equivalent to or slightly greater than the flame-spread rate of the linear droplet array.
• Flame Spread and Group-Combustion Excitation in Randomly Distributed Droplet Clouds with Low-Volatility Fuel near the Excitation Limit: a Percolation Approach Based on Flame-Spread Characteristics in Microgravity

  Masato Mikami; Herman Saputro; Takehiko Seo; Hiroshi Oyagi

  MICROGRAVITY SCIENCE AND TECHNOLOGY SPRINGER 30 (4) 419 - 433 0938-0108 2018/08 [Refereed]
   

  Stable operation of liquid-fueled combustors requires the group combustion of fuel spray. Our study employs a percolation approach to describe unsteady group-combustion excitation based on findings obtained from microgravity experiments on the flame spread of fuel droplets. We focus on droplet clouds distributed randomly in three-dimensional square lattices with a low-volatility fuel, such as n-decane in room-temperature air, where the pre-vaporization effect is negligible. We also focus on the flame spread in dilute droplet clouds near the group-combustion-excitation limit, where the droplet interactive effect is assumed negligible. The results show that the occurrence probability of group combustion sharply decreases with the increase in mean droplet spacing around a specific value, which is termed the critical mean droplet spacing. If the lattice size is at smallest about ten times as large as the flame-spread limit distance, the flame-spread characteristics are similar to those over an infinitely large cluster. The number density of unburned droplets remaining after completion of burning attained maximum around the critical mean droplet spacing. Therefore, the critical mean droplet spacing is a good index for stable combustion and unburned hydrocarbon. In the critical condition, the flame spreads through complicated paths, and thus the characteristic time scale of flame spread over droplet clouds has a very large value. The overall flame-spread rate of randomly distributed droplet clouds is almost the same as the flame-spread rate of a linear droplet array except over the flame-spread limit.
• Flame spread between two droplets of different diameter in microgravity

  Masato Mikami; Naoya Motomatsu; Kentaro Nagata; Yasuko Yoshida; Takehiko Seo

  COMBUSTION AND FLAME ELSEVIER SCIENCE INC 193 76 - 82 0010-2180 2018/07 [Refereed]
   

  This research investigates the flame-spread characteristics between two droplets, Droplets A and L, of different diameter. n-Decane droplets are placed at intersections of 14 mu SiC fibers. The flame spread from Droplet A to Droplet L was observed in microgravity. The results show that the flame-spread rate decreases with an increase in the droplet spacing or the initial diameter of Droplet L for a constant initial diameter of Droplet A. The flame-spread time is approximated as the summation of the thermal conduction time from the flame around Droplet A to Droplet L and the heating time of Droplet L, which is the time required to activate the vaporization of Droplet L. Both the thermal conduction time and the heating time of Droplet L increase with the droplet spacing. The latter also linearly increases with the squared initial droplet diameter of Droplet L. The results suggest that the ratio of the heating time of Droplet L to the thermal conduction time depends roughly on the droplet diameter of Droplet L alone for a constant initial diameter of Droplet A. The flame-spread-limit droplet spacing gradually decreases with an increase in the initial droplet diameter of Droplet L and increases sharply with the initial droplet diameter of Droplet A. The flame-spread time is limited by the burning lifetime of Droplet A and about 80% of the burning lifetime of Droplet A under the near-flame-spread-limit condition. The flame-spread limit is discussed considering the burning lifetime of Droplet A, the thermal conduction time, and the heating time of Droplet L. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
• Analysis of Local Flame-Spread Characteristics of an Unevenly Arranged Droplet Cloud in Microgravity

  Yasuko Yoshida; Narita Sano; Takehiko Seo; Masato Mikami; Osamu Moriue; Yuji Kan; Masao Kikuchi

  INTERNATIONAL JOURNAL OF MICROGRAVITY SCIENCE AND APPLICATION JAPAN SOC MICROGRAVITY APPLICATION 35 (2) 350203 - 350203 0915-3616 2018 [Refereed]
   

  As a preliminary experiment of the "Group Combustion" experiment conducted in the Japanese Experiment Module "Kibo" aboard the International Space Station (ISS) in 2017, a combustion experiment of an unevenly arranged droplet cloud with 148 n-decane droplets tethered on a SiC-fiber lattice was conducted in microgravity during parabolic flight of an aircraft. In this study, three methods of identifying the local flame-spread direction were proposed to determine the local flame-spread rate between two adjacent droplets of an unevenly arranged droplet cloud considering the local flame-spread direction. The first method employed the vertical direction from the isothermal line to the unburned droplet. The isothermal line was approximated based on the luminance of SiC fibers tethering droplets. The second method considered the luminance distribution of the initial flame immediately after ignition. The third method compared the local flame-spread-rate candidates from neighboring droplets with the flame spread-rate of the linear droplet array. It was possible to identify the local flame-spread direction by any one of these methods, and the local flame-spread rate is calculated between two droplets close to this direction. The results suggest that there are many conditions under which the local flame-spread rate of an unevenly arranged droplet cloud is greater than the flame spread rate of the linear droplet array.
• OPTIMIZATION OF FLAME STABILIZATION LIMITS IN MESO-SCALE TUBE COMBUSTORS WITH WIRE MESH

  Fudhail Abdul MUNIR; Takehiko SEO; Masato MIKAMI

  International Journal of Mechanical & Mechatronics Engineering 17 (6) 186 - 192 2017/12 [Refereed]
  
• Group Combustion Excitation in Randomly Distributed Droplet Clouds Based on Flame-spread Characteristics with Two-droplet Interaction in Microgravity

  Herman Saputro; Laila Fitriana; Masato Mikami; Takehiko Seo

  Proceedings of 23rd Small Engine Technology Conference JSAE 20179077/SAE 2017-32-0077 - JSAE 20179077/SAE 2017-32-0077 2017/11 [Refereed]
  
• Study on Spray Characteristics of Pressure Swirl Atomizer with Swirling Air Flow under the Subatmospheric Pressure

  Takehiko Seo; Naoki Hiruta; Masata Mikami

  Proceedings of the 19th Annual Conference on Liquid Atomization and Spray Systems-Asia P1_099 - P1_099 2017/10 [Refereed]
  
• Time-frequency characteristics of combustion impact and noise in a diesel engine with two-stage combustion

  Masato Mikami; Koki Minato; Shodai Sagara; Yoshiki Sumida; Takehiko Seo

  COMODIA 2017 - 9th International Conference on Modeling and Diagnostics for Advanced Engine Systems B206 - B206 2017/07 [Refereed]
   

  Copyright © 2017 by the Japan Society of Mechanical Engineers. This study experimentally investigated the characteristics of engine-noise generation in a single-cylinder diesel engine with two-stage combustion in which noise cancelling and amplifying would occur at frequencies for two combustion impacts with opposite and the same phases, respectively. We employed two-stage injection using a common-rail injection system and analyzed the in-cylinder pressure and sound pressures using FFT and wavelet transform analyses to study the time-frequency characteristics of the combustion impact and noise for different intervals of two combustion impacts. Depending on the engine structure, there are some main frequencies of combustion noise, whose noise components are greatly affected by the combustion impact and contribute to the overall level of engine noise. The noise power level at each main frequency rapidly increases over time near the combustion TDC and decays during the expansion stroke. The results clearly show that the combustion impact power is suppressed near the combustion TDC at cancelling frequencies and is increased at an amplifying frequency. Such effects were also seen in the time-frequency characteristics of the noise power level. As the interval of two combustion impacts is increased, these frequencies decrease. We discuss the effect of the interval on the overall noise level considering the relationship between the main frequencies of combustion noise and cancelling and amplifying frequencies and describe a combustion noise generation model.
• Flame spread of droplet-cloud elements with two-droplet interaction in microgravity

  Masato Mikami; Hidetaka Watari; Tsutomu Hirose; Takehiko Seo; Herman Saputro; Osamu Moriue; Masao Kikuchi

  JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY JAPAN SOC MECHANICAL ENGINEERS 12 (2) 1 - 10 1880-5566 2017 [Refereed]
   

  This research conducted microgravity experiments to investigate the flame-spread characteristics of the fuel-droplet-cloud element with uneven droplet spacing, which is a basic element of a randomly distributed droplet cloud at the critical condition for group-combustion occurrence. Flame spread to a droplet followed by burning with two-droplet interaction was observed in microgravity to investigate the effect of flame-spread direction and local interactive effect. The results show that the flame-spread rate to a droplet in a perpendicular direction to the axis of two interacting droplets was greater than that to the droplet in the same direction as the axis of two interacting droplets. The temperature distribution around burning droplets was measured by the Thin Filament Pyrometry (TFP) method based on radiation from 14-micron SiC fibers suspending droplets at their intersections. The flame-spread-limit distance increased with two-droplet interaction in both flame-spread directions. This also shows the dependence of the flame-spread direction. The flame spreading after two-droplet interaction in different directions is discussed considering the temperature distribution development. An approximation of the flame-spread-limit distance is also presented.
• Extinction condition of counterflow spray diffusion flame with polydisperse water spray

  Mega Nur Sasongko; Takehiko Seo; Masato Mikami

  FIRE SAFETY JOURNAL ELSEVIER SCI LTD 82 23 - 29 0379-7112 2016/05 [Refereed]
   

  The effect of polydisperse water droplet size distribution on the burning behavior and extinction condition of counterflow spray diffusion flame was investigated experimentally in this study. N-heptane as liquid fuel spray and nitrogen as a carrier gas were introduced from the lower duct while water spray and oxidizer consisting of oxygen and nitrogen was issued from the upper duct. The burning behavior of spray flame for different fuel droplet size with and without water spray was observed and the extinction condition of counterflow spray diffusion flame was characterized by oxygen concentration at extinction. The results show that the minimum value of oxygen concentration at extinction for counterflow spray diffusion flame with water spray is similar to the extinction condition without water spray for higher mean droplet diameter of water. The minimum value of oxygen concentration at extinction shifts to the smaller fuel droplet size when decreasing the water droplet size. For fuel droplet size higher than 48 mu m, the optimum of water droplet size for suppressing counterflow spray diffusion flame was smaller than gaseous flame. The explanation of optimum water droplet size based on the coupled effect of Stokes number and vaporization Damkohler number can be used for prediction of the effectiveness of water droplet on the suppression of counterflow spray diffusion flame. (C) 2016 Elsevier Ltd. All rights reserved.
• Flame-Spread Characteristics of n-Decane Droplet Arrays at Different Ambient Pressures in Microgravity

  Narita Sano; Naoya Motomatsu; Herman Saputro; Takehiko Seo; Masato Mikami

  INTERNATIONAL JOURNAL OF MICROGRAVITY SCIENCE AND APPLICATION JAPAN SOC MICROGRAVITY APPLICATION 33 (1) 330108-1 - 330108-5 0915-3616 2016 [Refereed]
   

  This research involves microgravity experiments being conducted on flame spread over fuel droplet arrays at different pressures including low-pressure condition in order to improve understanding of flame-spread characteristics under high-altitude relight condition of jet engines. n-Decane was used as a fuel. The ambient pressure ranged from 25 to 200 kPa. The results show that the flame-spread rate and flame-spread limit distance decreased with an increase in ambient pressure. As the ambient pressure is increased, the thermal conduction time from the flame of a droplet to the next unburned droplet increases due to the decreased thermal diffusivity, and the droplet heating time also increases due to the increased fuel boiling point, resulting in a decrease in the flame-spread rate and-limit distance. The pressure effect on the flame-spread limit around two interactive burning droplets is also discussed.
• Droplet Cloud Combustion Experiment "Group Combustion" in KIBO on ISS

  Masato Mikami; Masao Kikuchi; Yuji Kan; Takehiko Seo; Hiroshi Nomura; Yusuke Suganuma; Osamu Moriue; Daniel L. Dietrich

  INTERNATIONAL JOURNAL OF MICROGRAVITY SCIENCE AND APPLICATION JAPAN SOC MICROGRAVITY APPLICATION 33 (2) 330208-1 - 330208-7 0915-3616 2016 [Refereed]
   

  Flame spread in fuel spray near the flame base and subsequent excitation of group combustion of the whole spray are necessary for stable combustion of continuous burning of liquid fuel such as in aero engines or gas turbines. In order to elucidate the flame spread mechanism, flame spread experiments of a fuel-droplet array in microgravity have been undertaken. Based on the past short-duration microgravity experiments and a percolation model to describe group combustion excitation of randomly distributed droplet clouds, the droplet cloud combustion experiment named "Group Combustion" is planned as the first combustion experiment in the Japanese Experiment Module "KIBO" on the International Space Station. The objective of this experiment is to verify the flame spread hypotheses regarding the effects of droplet interaction, droplet motion, and radiative heat loss from the flame. The Group Combustion Experiment Module (GCEM) has been developed as experiment-dedicated apparatus. This paper will provide an overview of the experiment.
• Effects of hydrogen addition to partially premixed spray flame on combustion and emission characteristics

  T.Matsumoto; T. Seo; M.Mikami

  Proceedings of International Gas Turbine Congress 2015 276 - 280 2015/11 [Refereed]
  
• レーザー着火の燃料噴霧場への適用と着火特性

  瀬尾健彦; 石村祐宜; 三上真人

  微粒化 24 (83) 8 - 12 2015/11 [Invited]
  
• Approaches to Enhance the Combustion in Meso-scale Cylindrical Tube Combustors

  Fudhail Abdul Munir; Tsuyoshi Tokumasa; Takehiko Seo; Masato Mikami

  Proceeding of The 26th International Symposium on Transport Phenomena ISTP-26-033 - ISTP-26-033 2015/09 [Refereed]
  
• Combustion and Noise Characteristics in a Diesel Engine with Hydrogen Addition and Pilot Injection

  Ryota Sakane; Toshiki Fujimura; Takehiko Seo; Masato Mikami

  SAE Technical Papers SAE International 2015- (September) JSAE 20159322/SAE 2015-01-1922 - JSAE 20159322/SAE 2015-01-1922 0148-7191 2015/09 [Refereed]
   

  We experimentally investigated effects of pilot diesel-fuel injection on ignition timing variation and noise reduction in a diesel engine with hydrogen addition to the intake pipe. The pilot diesel-fuel injection suppressed ignition timing variation which was significant under hydrogen addition conditions. The heat release by the pilot diesel-fuel injection stably acted as an ignition source of the hydrogen-air mixture. The maximum in-cylinder pressure rise rate increased with the hydrogen fraction. However, the sound pressure level attained minimum around a specific hydrogen fraction.
• Study of combustion and emission characteristics of diesel fuel/water emulsion (2st report, Effects of hydrogen addition on spray combustion)

  OKAMOTO Yuya; SRIWARDANI Nyenyep; SEO Takehiko; MIKAMI Masato

  Transactions of the JSME (in Japanese) The Japan Society of Mechanical Engineers 81 (821) 14 - 00256-14-00256 2187-9761 2015 [Refereed]
   

  This study experimentally investigated combustion and emission characteristics with hydrogen added to both diesel fuel spray and emulsion fuel spray. The water percentage of 5 vol% in W/O emulsion fuel was used. For experimental setup, a burner equipped with a twin fluid atomizer was used. Hydrogen was supplied near the flame base. Results show that the height and luminosity of flame increased with hydrogen fraction for both spray combustion of diesel fuel and emulsion fuel. The amounts of CO and THC emissions decreased by increasing hydrogen fractions with both fuels. However, flame luminosity with emulsion fuel was lower than that with diesel fuel alone even if hydrogen was added. The lower flame luminosity is caused by smaller amount of soot with emulsion fuel due to water gas shift reaction and by lower combustion temperature. The combustion temperature was decreased by increased sensible heat and latent heat by the presence of water in emulsion fuel. Also, the lower temperature decreased the amount of NO emissions in comparison with the case with diesel fuel alone.
• Ignition Timing Variation in a Diesel Engine with Hydrogen and Engine-oil Mist with Different Atomization Conditions Added to Intake Air

  Fujimura, T; Sakane, R; Nishino, M; Seo, T; Mikami, M

  Proceedings of the 17th Annual Conference on Liquid Atomization and Spray Systems-Asia ILASS-Asia2014-010 - ILASS-Asia2014-010 2014/11 [Refereed]
  
• Simulating flame-spread behavior in large scale of droplet clouds with considering two-droplet interaction

  Saputro, H; Seo, T; Mikami, M

  Proceedings of the 17th Annual Conference on Liquid Atomization and Spray Systems-Asia ILASS-Asia2014-058 - ILASS-Asia2014-058 2014/11 [Refereed]
  
• Microgravity Experiment of Flame Spread over Droplets at Low Pressure

  MIKAMI Masato; SANO Narita; SAPUTRO Herman; WATARI Hidetaka; SEO Takehiko

  International journal of microgravity science and application The Japan Society of Microgravity Application 31 (4) 172 - 172 2014 [Refereed]
   

  This research conducted microgravity experiments of flame spread over fuel-droplet arrays at a low pressure in order to improve understanding of the flame spread in fuel sprays under high-altitude relight condition of jet engines. The results show that both the flame-spread rate and flame-spread limit distance at the low pressure are greater than those at atmospheric pressure. The pressure effect on the flame-spread rate was discussed considering some elementary processes, such as droplet heating and thermal diffusion. The thermal diffusion speed is inversely proportional to the pressure. The pressure effect on the flame-spread limit distance was discussed considering transient process of high-temperature region around a burning droplet. The maximum radius of the outer edge of the high-temperature region is proportional to -1/3 power of the ambient pressure. Group combustion occurrence was also demonstrated with a percolation model considering the flame-spread limit.
• The Influence of Hydrogen Addition to Diesel Fuel Spray Combustion For Different Atomization Conditions

  Nyenyep Sriwardani; Yuya Okamoto; Takehiko Seo; Masato Mikami

  ADVANCES IN APPLIED MECHANICS AND MATERIALS TRANS TECH PUBLICATIONS LTD 493 33 - + 1660-9336 2014 [Refereed]
   

  The negative effects of hydrocarbon fuels are widely highlighted by increasing global warming and declining quality of human health. Therefore, it is important to reduce the level of emissions from liquid hydrocarbon combustion. Hydrogen addition to the combustion chamber is one of the proven methods to improve emssions level. In this research, an experiment was conducted on diesel fuel spray combustion with hydrogen addition. The effect of additional hydrogen was observed on CO, CO2, NO and THC exhaust gas emissions. A small hydrogen fraction (0 similar to 3 vol %) was added to the rich premixed spray combustion. The results show that increasing the hydrogen fraction reduced the emission indexes of CO and THC, and increased the emission index of CO2. Increasing the hydrogen fraction caused an increase in the emission index of NO, but the actual physical amount was insignificant. Increasing the atomizing air flow rate reduced the CO and THC emission indexes, but increased the CO2 and NO emission indexes.
• Study of combustion and emission characteristics of diesel fuel/water emulsion (1st report, Effects of atomization condition)

  AZRIZAL Tajul; OKAMOTO Yuya; SEO Takehiko; MIKAMI Masato

  Transactions of the JSME (in Japanese) The Japan Society of Mechanical Engineers 80 (816) TEP0230 - TEP0230 2187-9761 2014 

  Emulsion fuel is regarded as one of the possible fuels for reducing the emissions of pollutants from combustion systems. This study investigated the effect of droplet size on combustion and emission characteristics for both pure diesel and emulsion fuel in preheated ambient air. A burner equipped with a twin fluid atomizer was used to vary Sauter mean droplet diameter (SMD) of spray. Water percentage of 5 and 10 vol% in W/O emulsion fuel was used. Experimental results show that both emulsion fuel had lower EICO₂ than diesel fuel. This result shows combustion efficiency of emulsion fuel was lower than that of diesel fuel. As the preheated ambient air temperature T_Ambi was increased to 473 K, combustion efficiency of emulsion fuels was improved. In emulsion fuel combustion, NO emission was lower than pure diesel fuel combustion. The vaporization of water in emulsion fuels reduced local flame temperature and thus reduced the NO formation. Smaller fuel droplet SMD had higher NO emission for pure diesel fuel. However, NO emission had no dependence on fuel droplet SMD for emulsion fuel. Emulsion fuels also had lower flame luminance as compared with diesel fuel alone. This is caused by lower soot emission of emulsion fuels.
• A Study of Breakup Process of a Jet Fuel Simulant Liquid at Low Pressure

  Kanda, T; Seo, T; Mikami, M

  Proceedings of the 16th Annual Conference on Liquid Atomization and Spray Systems-Asia 361 - 366 2013/12 [Refereed]
  
• 対向流拡散火炎に対する水噴霧の消火メカニズムの解明

  田渡貴史; 瀬尾健彦; 三上真人

  微粒化 22 (76) 137 - 142 2013/11 [Refereed]
  
• IMPROVEMENT OF COMBUSTION STABILITY IN NARROW TUBES WITH WIRE MESH

  Munir, F.A; Hatakeda, N; Seo, T; Mikami, M

  Proceedings of 24th International Symposium on Transport Phenomena 2013/11 [Refereed]
  
• Study of Flame Spread Behaviour in Large-scale 2-D Droplet Clouds Without Interactive Effect Using Percolation Approach

  Saputro, H; Seo, T; Mikami, M

  Proceedings of 24th International Symposium on Transport Phenomena 2013/11 [Refereed]
  
• Experimental Study on Flame Spread of Droplet-cloud Elements with Two-droplet Interaction in Microgravity

  Mikami, M; Hirose, T; Watari, H; Seo, T; Moriue, O; Kikuchi, M

  Proceedings of The 25th European Conference on Liquid Atomization and Spray Systems 2013/09 [Refereed]
  
• Characteristics of whistle noise from mufflers with perforated pipes

  Tatsuya Yamada; Takehiko Seo; Masato Mikami; Takashi Esaki

  Proceedings of Meetings on Acoustics 19 1939-800X 2013 [Refereed]
   

  The purpose of this study is to improve understanding of whistle noise generation mechanism in mufflers with perforated pipes. First, we measured sound pressure of whistle noise radiating from a straight-through-type sub-muffler with a perforated pipe with steady flow. Results show that the frequency of predominant whistle noise became higher stepwisely with increasing the flow velocity and was higher with smaller hole diameter. Next, we measured the sound pressure of whistle noise radiating from an expansion-cavity-type main muffler with a perforated pipe. Predominant Strouhal number based on the hole diameter and flow velocity existed within a certain range while the hole diameter and flow velocity were varied. The frequency of predominant flow velocity fluctuation near holes of the perforated pipe was close to the frequency of predominant whistle noise. Under the same hole diameter and flow velocity condition, the straight-through-type muffler tended to generate whistle noise more than the expansion-cavity-type muffler. Comparison with experiments without the outer shell or an open window in the outer shell also show that the outer shell of muffler enhanced the whistle noise generation. © 2013 Acoustical Society of America.
• Combustion of gaseous and liquid fuels in meso-scale tubes with wire mesh

  Masato Mikami; Yoshiyuki Maeda; Keiichiro Matsui; Takehiko Seo; Lilis Yuliati

  PROCEEDINGS OF THE COMBUSTION INSTITUTE ELSEVIER SCIENCE INC 34 3387 - 3394 1540-7489 2013 [Refereed]
   

  Combustion of gaseous and liquid fuel in meso-scale tubes with wire mesh was studied experimentally. For C3H8/air mixtures, the flame can be stabilized near the mesh inside the tube without external heating even for smaller tube than the classical quenching diameter by heat recirculation from the burned gas to the unburned gas through heat conduction in the wall and mesh. The mesh enhances heat transfer from the heated wall to the unburned gas. For tubes larger than the classical quenching diameter, the flame can be stabilized inside the tube even outside the flashback limit by the heat recirculation. Within a specific range of flow velocity, the flame propagates at relatively high speed and extinction occurs near the mesh, but the flame can be stabilized near the mesh if the condition is gradually shifted from another condition with a stabilized flame. Therefore, the mesh can act as a combustion inhibitor or an enhancer. The two types of burning behavior are discussed based on two steady-state flames; normal flame and weak flame predicted by other researchers. Next, combustion of electro-sprayed ethanol/n-heptane mixtures inside a meso-scale tube with d = 3.5 mm with a single mesh and double meshes was studied. The flame can be stabilized near the mesh without external heating. If droplets passing through the mesh directly interact with the flame, heat loss and asymmetric flame shape occurs. The flame stabilization region with double meshes is larger than that with a single mesh and comparable to that for gaseous fuel combustor except for the wall wetting region. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
• A Study of Laser-induced Breakdown Ignition in Fuel Spray (1^st Report: The Effect of Number Density of Droplet on Characteristics of Plasma Generation)

  SEO Takehiko; HISATOMI Yasuhiro; MIKAMI Masato

  Journal of the Combustion Society of Japan Combustion Society of Japan 55 (171) 67 - 72 1347-1864 2013 

  In order to ignite fuel spray directly by a laser beam, it is necessary to investigate the characteristics of laserinduced breakdown ignition and generation of plasma as ignition sources in fuel spray. This study conducted experiments of laser-induced breakdown ignition in an ethanol spray and laser-induced breakdown in water mists by using the third harmonic of the Q-switched Nd:YAG laser. Photographs of the flame and the plasma were taken and laser beam energy for laser-induced breakdown was measured. The results of laser-induced breakdown ignition experiments show that the laserinduced breakdown ignition in a fuel spray was possible even at low incident energies that the laser-induced breakdown did not occur in air. The results of laser-induced breakdown experiments show that plasma was generated at the focal point in air, on the other hand, plasma was generated at multi-points in water mist. And the laser-induced breakdown occurred at much lower incident energy than that in air. The probability of breakdown occurrence increased with the incident energy and showed higher value at higher number density of water droplet.

• Effect of engine oil mist on cyclic variation of a diesel engine with hydrogen

  Jun Matsubara; Takashi Yagenji; Toru Miyamoto; Takehiko Seo; Masato Mikami; Hajime Kabashima

  Proceedings of the 8th International Conference on Modeling and Diagnostics for Advanced Engine Systems, COMODIA 2012 362 - 367 2012/12 [Refereed]
   

  The present study experimentally investigated combustion characteristics of a diesel engine with hydrogen and blowby components added to the intake air. In our previous studies, the ignition delay decreased with the increase in hydrogen fraction at late diesel-fuel injection timings. However, it is difficult to auto-ignite hydrogen earlier than diesel fuel, because the auto-ignition temperature of hydrogen is higher than that of diesel fuel. There must be some factors to ignite hydrogen. We focus on reaction of blowby components as a cause of hydrogen ignition earlier than diesel-fuel ignition. Copyright © 2012 by the Japan Society of Mechanical Engineers.
• Effect of Engine oil mist on Cyclic Variation of a Diesel Engine with Hydrogen

  Matsubara, J; Yagenji, T; Miyamoto, T; Seo, T; Mikami, M; Kabashima, H

  Proceedings of the Eighth International Conference on Modeling and Diagnostics for Advanced Engine Systems 362 - 367 2012/07 [Refereed]
  
• Liquid-fuel combustion in a narrow tube using an electrospray technique

  Lilis Yuliati; Takehiko Seo; Masato Mikami

  COMBUSTION AND FLAME ELSEVIER SCIENCE INC 159 (1) 462 - 464 0010-2180 2012/01 

  This study experimentally investigated the possibility of stable burning conditions of liquid fuel inside a narrow tube using an electrospray technique without external heating or a catalyst. The mixture of 30% volume ethanol and 70% volume n-heptane was used as a liquid fuel atomized by the electrospray method with single capillary-ring extractor-mesh collector electrode configuration placed inside a quartz glass tube with an inner diameter of 3.5 mm. A stable flame was established inside the narrow tube without wall wetting within a certain range of equivalence ratio for a fuel flow rate of 1 mL/h. This study confirmed that the role of the mesh as the collector was very important in establishing a stable flame inside the narrow tube. If the fuel flow rate was sufficiently large, wall wetting occurred and eventually stable burning stopped. (C) 2011 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
• Study on relationship between spray characteristics and internal flows inside mixing chamber of a Y-jet atomizer

  Otera, Y; Seo, T; Mikami, M; Watanabe, S; Tamura, M

  Proceedings of the 15th Annual Conference on Liquid Atomization and Spray Systems-Asia 361 - 366 2011/12 [Refereed]
  
• Study on Electrosprayed Liquid Fuel Combustion in a Narrow Tube: Flammability Limit and Flame Visualization

  Lilis, Y; Matsui, K; Maeda, Y; Seo, T; Mikami, M

  Proceedings of 24th European Conference on Liquid Atomization and Spray Systems 2011/09 [Refereed]
  
• Effect of Polydisperse Water Spray on the Extinction of Counterflow Spray Diffusion Flame

  Sasongko, M.N; Tado, T; Seo, T; Mikami, M

  Proceedings of 24th European Conference on Liquid Atomization and Spray Systems 2011/09 [Refereed]
  
• Study on Characteristics of Laser-induced Breakdown in Liquid Spray

  Seo, T; Hisatomi, Y; Mikami, M

  Proceedings of 24th European Conference on Liquid Atomization and Spray Systems 2011/09 [Refereed]
  
• DNS Investigation on Autoignition and Flame Propagation in HCCI Combustion

  FUKUMOTO Hiroaki; SEO Takehiko; SHIMURA Masayasu; FUKUSHIMA Naoya; TANAHASHI Mamoru; MIYAUCHI Toshio

  JFST The Japan Society of Mechanical Engineers 6 (1) 45 - 55 1880-5558 2011 

  2-dimensional direct numerical simulation (DNS) of autoignition and flame propagation of turbulent premixed mixture has been conducted to investigate the turbulent combustion mechanism in homogeneous charge compression ignition (HCCI) engines. CH₄-air mixtures with spatial inhomogeneity of temperature and equivalence ratio are investigated by considering a detailed kinetic mechanism. Since the combustion process depends on local characteristics of the mixture, an identification method of ignition or flame propagation is proposed based on behaviors of elementary reactions related to OH radical. The proposed identification method shows that the area fraction of the flame propagation region increases drastically with the increase of initial temperature fluctuations.
• Effects of hydrogen addition to intake mixture on cyclic variation of diesel engine

  Toru Miyamoto; Hirokazu Hasegawa; Takashi Yagenji; Takehiko Seo; Masato Mikami; Hajime Kabashima; Tomoyuki Hashimoto

  SAE Technical Papers 2011 [Refereed]
   

  The present study experimentally investigated cyclic variation of combustion characteristics of a diesel engine with hydrogen added to the intake air in detail. As the result, there were three ignition modes: (1) hydrogen ignition mode, (2) hydrogen-assisted ignition mode, and (3) diesel-fuel ignition mode. Ignition timing fluctuated from cycle to cycle in each ignition mode and between one ignition mode and another mode. As the coolant temperature was increased, the number of cycles in diesel-fuel ignition mode decreased, and indicated thermal efficiency and cyclic variation was improved. In the case with the blow-by gas introduced to intake port, preflame reaction of blow-by gas first occurred, ignited hydrogen, and then diesel-fuel was ignited by hydrogen combustion in hydrogen ignition mode and hydrogen-assisted ignition mode. © Copyright 2011 Society of Automotive Engineers of Japan, Inc. and SAE International.
• Effect of Mixture Fraction of Ethanol/Heptane Mixture on Spray Characteristics of Electrostatic Atomization

  KANGAWA Hiroshi; YULIATI Lilis; SEO Takehiko; MIKAMI Masato

  TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B The Japan Society of Mechanical Engineers 77 (773) 129 - 137 0387-5016 2011 

  The electrospray characteristics depend on liquid flow rate, applied voltage, electrode configuration and liquid properties such as electrical conductivity, surface tension and viscosity. This study experimentally investigated electrospray characteristics of binary liquid mixtures. The tested liquid was ethanol, which has relatively high electrical conductivity and low heating value as a liquid fuel, n-heptane, which has relatively low electrical conductivity and high heating value, and their mixtures. The electrical conductivity of the liquid mixture decreased rapidly with increasing heptane volume fraction for heptane volume fraction higher than 70 %. The electrospray characteristics for mixtures with heptane volume fraction less than 70 % were different from those with heptane volume fraction greater than 70 %. By increasing the applied voltage, the electrospray mode changed in the order as spindle, cone-jet and multijet below the heptane volume fraction of 70 %. For the heptane volume fraction of 90 %, however, the electrospray mode changed in the order as spindle, cone-jet, asymmetry cone-jet and plused jet. The onset voltage, over which the cone-jet mode appears, was decreased with increasing heptane volume fraction while heptane volume fraction was less than 70 %.
• A Numerical Study on Flame Spread Characteristics of Two-dimensional Droplet Cloud

  T. Seo; D. Azakami; Y. Tsuchida; M. Mikami

  Proceedings of the 14th Annual Conference on Liquid Atomization and Spray Systems-Asia 302 - 306 2010/10 [Refereed]
  
• Study of Combustion Characteristics of Diesel Fuel/Water Emulsion Spray

  Tajul Azrizal; Takehiko Seo; Masato Mikami

  Proceedings of the 14th Annual Conference on Liquid Atomization and Spray Systems-Asia 297 - 301 2010/10 [Refereed]
  
• The effects of fluid viscosity and atomizing air flow rate on spray characteristics of a Y-jet atomizer

  Yuichiro OTERA; Haruki INOUE; Takehiko SEO; Masato MIKAMI; Shinji WATANABE; Masato TAMURA

  Proceedings of the 14th Annual Conference on Liquid Atomization and Spray Systems-Asia 86 - 91 2010/10 [Refereed]
  
• The effect of ambient air flows on spray characteristics of a pressure atomizer

  Haruki Inoue; Yuichiro Otera; Takehiko Seo; Masato Mikami; Kimiyoshi Sato

  Proceedings of the 14th Annual Conference on Liquid Atomization and Spray Systems-Asia 220 - 224 2010/10 [Refereed]
  
• Effects of initial temperature of premixed gas on ignition by use of laser-induced breakdown

  Jun Hayashi; Yusuke Sawanaka; Noriaki Nakatsuka; Tomoki Okada; Fumiteru Akamatsu; Takehiko Seo; Terushige Hori

  Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B Japan Society of Mechanical Engineers 76 (772) 2242 - 2248 0387-5016 2010 [Refereed]
   

  Laser-induced ignition gathers attention as the relatively new technique of ignition owing to its flexibility of ignition point that could be of benefit for stability and combustion efficiency in the lean premixed combustion. In this study, the laser-induced ignition phenomena have been investigated experimentally, especially on the relation between the initial temperature of the premixed gas and the minimum ignition energy. Methane/air mixture is used as the premixed gas. The initial temperature of premixed gas is varied from 300 K to 450 K under the constant molar density. Results clearly show that the absorption energy to the plasma is not affected by the increase of the initial temperature of premixed gas. In addition, the minimum incident energy for ignition decreases with the increase of initial temperature of premixed gas. Eventually, the increase of the initial temperature improves the ignitability of premixed gas by the laser-induced ignition.
• Development of a Pellet Catalytic Combustor for a Small Scale Generation System Using Near Infrared Ray Irradiation

  Go Ohmura; Tatsuya Keida; Takehiko Seo; Chulju Ahn; Fumiteru Akamatsu; Masahiko Shibahara

  JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY JAPAN SOC MECHANICAL ENGINEERS 4 (4) 453 - 461 1880-5566 2009 [Refereed]
   

  Several geometric types of the small scale catalytic combustors applying the pellet catalysts as both the heat source and the emitter for infrared ray generation were developed in order to investigate the catalytic combustion phenomenon and the effective operation conditions for the TPV generation system. The results of temperature measurements and exhaust gas analyses showed that there were the optimal width and length of the combustor geometry for the high combustion efficiency and the reduction of the residual CO concentration. The ultraviolet and visible spectral measurements showed that the surface chemical reaction was predominant in the catalytic combustion and the gas phase reaction which causes higher temperature and higher reaction rate than those of the surface reaction scarcely occurred in the developed combustor. The near infrared spectral measurements showed that the pellet catalysts in the combustor could play the role of the emitter for the TPV generation system.
• Huge Direct Numerical Simulation of Turbulent Combustion-Toward Perfect Simulation of IC Engine

  Journal of Computational Fluids Engineering 13 (4) 114 - 125 2008
• OH*, CH*ラジカル自発光を用いた予混合火炎の燃焼診断法についての考察

  瀬尾 健彦; 赤松 史光; 芝原 正彦; 香月 正司

  日本燃焼学会誌 48 (144) 206 - 213 2008 [Refereed]
  
• バイオ液体燃料の噴霧燃焼特性に関する研究（燃料種のすす生成特性への影響）

  赤間和樹; 林 潤; 瀬尾健彦; 安 鐵朱; 赤松史光; 橋本 望; 西田啓之

  微粒化 17 (58) 95 - 101 2008 [Refereed]
  
• Study on Soot Formation in Spray Flames (Effect of Droplet Size Distribution):Effect of Droplet Size Distribution

  HAYASHI Jun; AKAMATSU Fumiteru; AHN Chulju; SEO Takehiko; WATANABE Hiroaki; KUROSE Ryoichi

  TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B The Japan Society of Mechanical Engineers 74 (738) 429 - 437 0387-5016 2008 

  Effect of the droplet size distribution of fuel spray on the soot formation process in spray flames is investigated. The vibratory orifice atomizer is used to control the droplet size distribution of fuel spray. Two-dimensional soot volume fraction and primary soot particle size are measured by the Time-Resolved Laser Induced Incandescence (Time-Resolved LII) method and direct numerical simulation. The relationship between spatial distribution of fuel droplets and soot formation area are observed by the LII method and Interferometric Laser Imaging Droplet Sizing (ILIDS) method. The results show that flame structures of spray flame and soot formation process are affected critically by the mean droplet size of fuel spray. The mean soot formation area is increased by increase of the mean droplet size of fuel spray. The primary soot particles become large at around the edge of soot formation area. This trend mainly occurs from surface growth of soot particles. The group of some droplets and its vapor forms the soot formation area, and the large droplet of liquid fuel deforms shape of the soot formation area.
• 1908 Optical Measurements of Methane-Pure Oxygen Nonpremixed Flames under High Pressure

  NAKAO Yoshinori; IINO Kimio; HAYASHI Jun; AHN Chulju; SEO Takehiko; AKAMATSU Fumiteru

  The proceedings of the JSME annual meeting The Japan Society of Mechanical Engineers 2007 337 - 338 2007 

  In practical combustors such as gas turbine engine and jet engine, these combustions are performed under high pressure. High-pressure combustion has a merit to achieve high load combustion that means high heat value per unit volume. In addition, pure oxygen combustion has a merit to attain high flame temperature with no NO_x mission. However, studies on combustion mechanism of flame under high pressure have not been reported sufficiently. Especially, almost no studies on pure oxygen combustion under high pressure have been reported so far. In the present study, we targeted methane-pure oxygen nonpremixed flames under high pressure and examined the spectrum of flame luminescence by using Multi-Color Integrated Cassegrain Receiving Optics (MICRO) system. It is found that, under atmospheric pressure, color of the flame is indigo caused by line spectrum of CH^* radical (430nm) and that, under high pressure, line spectrum of CH^* is disappeared and color of the flame become white caused by band spectrum of CO-O^* radical (350〜500nm).
• 1839 Effect of Droplet Size Distribution of Fuel Spray on Soot Formation in Counter-flow

  HAYASHI Jun; SEO Takehiko; AHN Chulju; AKAMATSU Fumiteru

  The proceedings of the JSME annual meeting The Japan Society of Mechanical Engineers 2007 183 - 184 2007 

  Effect of the droplet size distribution of fuel spray on the soot formation process in spray flames is investigated. The vibratory orifice atomizer is used to control the droplet size distribution of fuel spray. Two-dimensional soot volume fraction, primary soot particle size and relationship between spatial distribution of fuel droplets and soot formation area are observed by optical measurements. The results show that flame structures of spray flame and soot formation process are affected critically by the mean droplet size of fuel spray. The mean soot formation area is increased by increase of the mean droplet size of fuel spray. The primary soot particles become large at around the edge of soot formation area. This trend occurs from coagulation and surface growth of soot particles. The group of some droplets and its vapor forms the soot formation area, and the large droplet of liquid fuel deforms shape of the soot formation area.
• 1813 Laser spark ignition: effect of temporal and spatial profile of laser

  SAWANAKA Yusuke; SEO Takehiko; AHN Chulju; AKAMATSU Fumiteru; Hori Terushige

  The proceedings of the JSME annual meeting The Japan Society of Mechanical Engineers 2007 153 - 154 2007 

  Laser-induced breakdown and the ignition were occurred by focusing a 532nm pulse from Q-switched Nd: YAG laser. Methane-air premixture at 1 atm was ignited in a constant volume chamber. In this study, we investigated how the temporal and spatial profile of laser pulse and characteristics of collecting lens have an effect on the breakdown thresholds and the minimum laser pulse energies (MPE) needed for ignition. This measurement result showed that excitation energy of flash lamp changes not only the laser energy but also the temporal and spatial profile of laser pulse. As excitation energy of flash lamp decreases, the laser pulse duration become longer and the spatial profile is getting closer to Gaussian distribution. As a result, MPE depend largely on the temporal and spatial profile of laser pulse. Specifically, as excitation energy of flash lamp decreased, MPE decreased.
• カセグレン光学系を用いた温度とラジカル自発光の局所同時計測 第1報, 計測システムの構築と計測精度の評価

  瀬尾健彦; 赤松史光; 芝原正彦; 香月正司

  日本機械学会論文集 B編 71 (708) 2169 - 2176 2005 [Refereed]
  

Conference Activities & Talks

• 定容容器を用いた高温高圧環境下における火炎振動とエンドガスの自着火 がノック強度に与える影響  [Not invited]

  常藤 飛鳥; 西村 凌平; 瀬尾 健彦; 三上 真人; 下栗 大右; 河野 通治

  第58回燃焼シンポジウム  2020/12
• 微小重力場での正デカン液滴間燃え広がりにおける干渉２液滴の二段着火 に関する研究  [Not invited]

  千頭 勇斗; 松本 昂大; 瀬尾 健彦; 三上 真人

  第58回燃焼シンポジウム  2020/12
• 燃料噴霧のレーザー着火における初期火炎核形成時の燃料液滴の挙動  [Not invited]

  齊木 勇志; 瀬尾 健彦; 三上 真人

  第58回燃焼シンポジウム  2020/12
• 定容容器を用いた自着火を伴う条件での火炎伝播挙動についての調査  [Not invited]

  西村 凌平; 常藤 飛鳥; 瀬尾 健彦; 三上 真人; 下栗 大右; 河野 通治

  熱工学コンファレンス 2020  2020/10
• 静電噴霧を用いた3 mm内径管型燃焼器における火炎定在に関する研究  [Not invited]

  桑田 孝駿; 瀬尾 健彦; 三上 真人

  熱工学コンファレンス 2020  2020/10
• Study on stabilized combustion of hydrocarbon fuel/air mixture in a small disk-type combustor

  MIYADE Takayuki; KUWATA Takatoshi; SEO Takehiko; MIKAMI Masato

  The Proceedings of Conference of Chugoku-Shikoku Branch  2020  The Japan Society of Mechanical Engineers
  
• Study on hydrocarbon blended fuels for micro-combustor with electrospray

  HANKAWA Naofumi; SEO Takehiko; MIKAMI Masato

  The Proceedings of Mechanical Engineering Congress, Japan  2018  The Japan Society of Mechanical Engineers
   

  As a new small-size energy source using a liquid hydrocarbon fuel, micro-combustor with liquid fuel is expected to be put into practical use. Many issues, however, still remain for practical application of micro-combustor. One of them is the difficulties in complete vaporization of liquid fuel and flame stabilization inside a limited space. This study employed the electrospray, studied a suitable hydrocarbon blended fuel to micro-combustor from viewpoints of calorific value, electrical conductivity, etc., and investigated the limit of flame stabilization inside the combustor.

• A study of sound source location of radiated noise in a single-cylinder diesel engine with two-stage combustion

  MINATO Koki; OGUCHI Hitosi; SEO Takehiko; MIKAMI Masato

  The Proceedings of Mechanical Engineering Congress, Japan  2018  The Japan Society of Mechanical Engineers
   

  Two-stage combustion was generated by two-stage fuel-injection with a single cylinder diesel engine. The sound source locations were identified for one of the main noise frequencies by using a sound source visualization device for different second fuel-injection timings, -10 deg. ATDC and -6 deg. ATDC, when the two-combustion impacts are amplified and cancelled at 2500 Hz, respectively. The results show that there were a few sound sources and the sound pressure level near each sound source increased first, attained maximum and decreased over time. The maximum sound pressure level for each sound source for the second stage fuel-injection start timing of -10 deg. ATDC was greater than that for the second stage fuel-injection start timing of -6 deg. ATDC. The decay rate was greatest for the sound source with the maximum sound pressure level in the present engine.

• A measurement of laminar flame speed of gasoline surrogate fuel / air mixture under high pressure condition using double kernel method

  KANEKO Hirotsugu; SEO Takehiko; MIKAMI Masato

  The Proceedings of Mechanical Engineering Congress, Japan  2018  The Japan Society of Mechanical Engineers
   

  Laminar flame speed plays an important role in turbulent combustion models used in engine combustion simulation. A laminar flame speed of gasoline surrogate fuel and isooctane / air mixture under high pressure condition simulating the inside of an engine cylinder was obtained by double kernel method using laser excitation plasma. Pressure dependence of laminar flame speed was investigated.

• Characteristics of Sound Radiation from Outer Surface of Automobile Muffler with Steady Internal Flow.

  IREI Hiroaki; MIKAMI Masato; SEO Takehiko

  The Proceedings of Mechanical Engineering Congress, Japan  2018  The Japan Society of Mechanical Engineers
   

  In recent years, flat shape mufflers have been employed to save for space a trunk room and an indoor space. However, when flattening the muffler, the sound pressure level due to sound radiation from the muffler outer surface increases. We investigated sources of a flat shape muffler with s steady internal flow by using NAH method and measured vibration acceleration on the outer surface of the muffler and velocity fluctuation of the flow inside the muffler in order to identify the excitation source by the internal flow.

• The effect of spray characteristics on ignitability of laser induced breakdown ignition in fuel spray

  立石 寛達; 瀬尾 健彦; 三上 真人

  微粒化シンポジウム講演論文集  2017/12  日本液体微粒化学会
  
• Study on spray structure of pressure swirl atomizer with swirling air flow at subatmospheric pressure

  蛭田 眞生; 瀬尾 健彦; 三上 真人

  微粒化シンポジウム講演論文集  2016/12  日本液体微粒化学会
  
• Study on heat and mass transfer during pyrolysis of a few kinds of pulverized coals

  Kawamoto Kouya; Yamaji Keito; Tanoue Ken-ichiro; Nishimura Tatsuo; Mikami Masato; Seo Takehiko

  The Proceedings of the Thermal Engineering Conference  2016  The Japan Society of Mechanical Engineers
   

  The dependence of volatile content of pulverized coal on its pyrolytic conversion has been investigated to understand heat and mass transfer. For coal with having about 40 % (coal A) volatile the char yield decreased dramatically with temperature until 823 K and approached slowly to the constant value. On the other hand, the decrement of char yield with temperature for coal with having about 30 % volatile (coal B) was smaller than that for coal A. The temperature increased slowly with time during gas generating and was equal or higher than 373 K for coal A. So, generated gas could include not only moisture but also part of released volatile. On the other hand, the generated gas volume for coal B was smaller than that for coal A. The coal A was more thermal decomposable material than coal B. The time course of generated gas volume and temperature during pyrolysis at T_R = 1023 K was different from that at T_R = 623 K because the coal B could decompose to the lighter tar than that for the coal A.

• Characteristics of Laser-induced Ignition in Liquid Ethanol Spray

  瀬尾 健彦; 石村 祐宜; 三上 真人

  微粒化 = Atomization : journal of the ILASS-Japan  2015/11  日本液体微粒化学会
  
• Effects of ambient air pressure on the behavior of a jet fuel simulant liquid film injected though swirl injector

  永野 佑樹; 蛭田 眞生; 瀬尾 健彦

  日本航空宇宙学会西部支部講演会講演集  2015  [日本航空宇宙学会西部支部]
  
• F132 Study of the measurement technique of laminar burning velocity by Double kernel method

  Matsuo Tsubasa; Seo Takehiko; Mikami Masato

  The Proceedings of the Thermal Engineering Conference  2015  The Japan Society of Mechanical Engineers
   

  We measured the laminar burning velocity for the CH_4/Air premixed using the double kernel method as pre-stage before measuring the laminar burning velocity of gasoline and its surrogate. We also examined the influence of pressure on the laminar burning velocity. The experimental results show that the double kernel method can be utilized to measure the laminar burning velocity, but we need to review the analytical method. For the case where the distance between plasma is 50 mm, we found that the pressure corresponds to the laminar burning velocity is two times higher than the initial pressure.
• H114 Study on dependence of ratio of pulverized coal and polystyrene on its co-pyrolytic conversion

  Kasai Kazuhiro; Kawamoto Kouya; Teramoto Takahiro; Tanoue Ken-ichiro; Nishimura Tatsuo; Mikami Masato; Seo Takehiko

  The Proceedings of the Thermal Engineering Conference  2015  The Japan Society of Mechanical Engineers
   

  Heat and mass transfer during co-pyrolysis of packed bed of pulverized coal and polystyrene have been investigated. Mass fraction of the pulverized coal in the mixed powder and polystyrene was changed from 0.00 to 1.00. The temperature in the packed bed of pulverized coal increased monotonously with time and approached to the steady state value of it except for until 375 K due to the evaporation of water. On the other hand, temperature in the packed bed of polystyrene bed increased initially with time and then didn't change due to endothermic pyrolysis of it at 450K. After that the temperature increased again and approached to the steady state value. The co-pyrolysis rate could controlled by the decomposition of pulverized coal when the mass fraction of the coal was greater than 0.25.
• The influence of kinematic viscosity of a jet fuel simulant liquid on its breakup process at low pressure

  神田 智行; 永野 佑樹; 瀬尾 健彦

  微粒化シンポジウム講演論文集  2014/12  日本液体微粒化学会
  
• The effect of ethanol spray concentration on laser-induced breakdown ignition

  石村 祐宜; 瀬尾 健彦; 三上 真人

  微粒化シンポジウム講演論文集  2013/12  日本液体微粒化学会
  
• W071002 An Attempt of developing laser-induced ignition technique : Characteristics of laser-induced ignition in liquid fuel spray

  SEO Takehiko

  The Proceedings of Mechanical Engineering Congress, Japan  2013  The Japan Society of Mechanical Engineers
   

  To ignite fuel spray with a laser beam directly, it is necessary to investigate the characteristics of laser-induced breakdown in fuel spray. In this present study, the effects of incident energy and spray characteristics on the breakdown and ignition characteristics were investigated experimentally. Laser-induced breakdown ignition experiments was conducted in ethanol spray by using the third harmonic of the Q-switched Nd:YAG laser (wavelength λ=355 nm, pulse width is about 6 ns and maximum output energy is about 375 mJ/pulse) as a laser source. Probability of breakdown occurrence and ignition for different incident energy and droplet number density were obtained. And to clarify the ignition mechanism, the Schlieren images of the plasma and flame propagation process were taken. It found that there is a large gap between the required incident energy for breakdown and ignition in ethanol spray. And plasma is generated by the multiple points in ethanol spray. In case of ignition success, flame kernels ware formed around each plasma.
• G061062 Pyrolysis experiment of pulverized coal

  MATSUURA Hiroki; MURATA Shoma; NISHIMURA Tatsuo; TANOUE Kenichiro; MIKAMI Masato; SEO Takehiko

  The Proceedings of Mechanical Engineering Congress, Japan  2013  The Japan Society of Mechanical Engineers
   

  In this report, temperature and gas generation of pulverized coal during pyrolysis under nitrogen atmospheric condition has been measured to understand heat and mass transfer before its combustion. A furnace was heated at 400 K/h until a setting temperature, TS. After that, the temperature at a wall of the furnace was kept at TS for 0.5 h. For TS = 873K, the gas flow rate had a 1^ peak at t = 50 min. A temperature in the packed bed, Tpc, was about 400 K at the time. So, the 1^ peak was caused by evaporation of water. As time elapsed, the gas flow rate became increasing at t = 65 min. The Tpc was about 490 K. For t > 65 min, the gas flow rate had a 2^ peak at Tpc = 650 K with exothermic reaction, which was caused by polymerization. At TS = 1073 K, it was found that not only heat transfer but also gas generation due to the exothermic polymerization became more obvious than those at TS = 873K.
• A115 Experimental Study on Flame-spread Characteristics of Fuel Droplet-cloud Elements by TFP Method

  WATARI Hidetaka; HIROSE Tsutomu; SEO Takehiko; MIKAMI Masato

  The Proceedings of the Thermal Engineering Conference  2013  The Japan Society of Mechanical Engineers
   

  This research conducted microgravity experiments to investigate flame-spread characteristics of droplet-cloud element. The results show that the flame-spread rate to the droplet in the perpendicular direction to the axis of two droplet interaction was greater than that to the droplet in the same direction to the axis of two droplet interaction. The flame-spread-limit distance also increased with the perpendicular direction to the axis of two droplet interaction. The temperature distribution around burning droplets was measured by Thin Filament Pyrometry (TFP) method based on visible light radiation from SiC fibers suspending droplets.
• C124 Experimental study on multi-jet-mode electrospray

  HATAKEDA Naoyuki; MUNIR F.A.; SEO Takehiko; MIKAMI Masato

  The Proceedings of the Thermal Engineering Conference  2013  The Japan Society of Mechanical Engineers
   

  Recently, micro-combustors which combust hydrocarbon fuels at micro scale are expected to be used as a small energy source. Since fast evaporation of liquid fuel is required, electrospray techniques, which can generate small droplets, have been employed. We focus on the multi-jet-mode electrospray, which produces many jets from a single capillary. We investigate effect of applied voltage to the capillary and fuel flow rate on the jet characteristics by visualization using a laser light sheet and nano flash shadow graph system. The investigation was conducted for some different diameters of capillaries and distance between the capillary grounded mesh.
• Study on role of droplet in characteristics of laser-induced plasma generation in spray : Effect of droplet position in spray  [Not invited]

  SEO Takehiko; HISATOMI Yasuhiro; MIKAMI Masato

  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  2012/12
• Study of the fire extinguishing mechanism of water spray on counterflow diffusion flame  [Not invited]

  TADO Takafumi; SEO Takehiko; MIKAMI Masato

  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  2012/12
• Activity Report of Research Team on Combustion Dynamics of Fuel Droplets

  Kikuchi Masao; Yamamoto Shin; Umemura Akira; Kobayashi Hideaki; Ogami Yasuhiro; Nomura Hiroshi; Mikami Masato; Seo Takehiko; Moriue Osamu; Shinjo Junji

  宇宙利用シンポジウム: 第27回: 平成22年度 = Space Utilization Research, Vol. 27 2011: Proceedings of The Twenty-seventh Space Utilization Symposium  2011/03  Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)
   

  The Twenty-seventh Space Utilization Symposium (January 24-25, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa JapanThis paper describes activity report of Research Team(WG) on Combustion Dynamics of Fuel Droplets. In accordance with the objectives of this WG, normal gravity and ground-based microgravity experiments have been performed as well as numerical simulation. Also, discussion on next-generation simulation technique for spray combustion has been discussed. It should be emphasized that a proposal on microgravity experiment for validation of the new atomization concept, which was prepared by Prof. Umemura, was newly selected as a candidate for KIBO experiment. The investigation is the 3rd space experiment, derived from our WG activities, following previous 2 space experiments.Number of authors: 11Physical characteristics: Original contains color illustrations
• Combustion Dynamics and NOx Emission of a Turbulent Swirl Stabilized Combustor with Secondary Fuel Injection :  [Not invited]

  Rouzbeh Riazi; Shimura Masayasu; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio

  日本流体力学会年会講演論文集  2009  日本流体力学会
   

  To study the effects of flow rate, diameter and offset of secondary fuel injection on combustor noise level, pressure fluctuation and NOx emission, three types of injectors were examined in the swirl-stabilized combustor for total flow rate of 300(l/m) and total equivalence ratio of 0.7～0.9. Secondary fuel injection of 3.0(l/m) is the best condition for the reduction of pressure fluctuation and combustion noise with tolerable NOx emission for the reference injector used in the previous studies. As for the injector with injection offset, although Q_=4.2(l/m) is more relevant for the reduction of NOx emission and pressure fluctuation for φ≥0.85, noise level and pressure fluctuation are still larger than the reference injector. In addition, spectral analysis of pressure fluctuations revealed that the large amount of secondary fuel injection with offset induces a lot of new modes in broad range of frequency.
• Analysis of Aerodynamic Sound Source by Time-Resolved Stereoscopic PIV  [Not invited]

  OBANA Koichi; SEO Takehiko; SHIMURA Masayasu; TANAHASHI Mamoru; MIYAUCHI Toshio

  日本流体力学会年会講演論文集  2009  日本流体力学会
   

  Investigation of sound generation mechanism in flow fields is important for reduction of aerodynamic sound. The detailed investigation of sound sources requires velocity measurements with high temporal and spatial resolutions. In this study, sound sources in turbulent mixing layer have been investigated by time-resolved stereoscopic particle image velocimetry (PIV). Powell's sound source and Reynolds stress component of Lighthill's sound source have been evaluated from experimental results and compared with those obtained from the previous direct numerical simulation. It is shown that estimation of Powell's sound source is effective for the analysis of aerodynamic sound source in restricted measurement regions, and that evaluation of Reynolds stress component is useful for the analysis if measurable velocity is limited in two components. In addition, spectral analysis for temporal variations of vorticity and sound sources reveals that frequency of sound generated in mixing layer is dominated by the generation of large-scale vortical structures.
• F0701(2) 複数化学種PLIFとステレオPIVの同時計測による乱流予混合火炎の構造解明([F0701]光に着目した燃焼現象の計測法,先端技術フォーラム)  [Not invited]

  志村 祐康; 瀬尾 健彦; 店橋 護; 宮内 敏雄

  年次大会講演資料集  2009  一般社団法人 日本機械学会
  
• A123 Investigation of Local Extinction Mechanism by Direct Numerical Simulation of Methane-Air Turbulent Premixed Flame  [Not invited]

  Yamaguchi Takuya; Shimura Masayasu; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio

  The Proceedings of the Thermal Engineering Conference  2009  The Japan Society of Mechanical Engineers
   

  Three-dimensional direct numerical simulation (DNS) of methane-air turbulent premixed flame with a realistic reduced kinetic mechanism has conducted to investigate effects of turbulence characteristics on the local heat release rate. Numerical condition of the DNS is classified into thin reaction zones of combustion diagram proposed by Peters. Quite low heat release rate regions corresponding to the local extinction are observed. In the vicinities of these regions, flame elements are strongly stretching into two tangential directions. The local extinction mechanism was clarified by introducing life time of reactive species relative to strong coherent fine scale eddies in turbulence.
• A114 Propagation of Methane-Air Premixed Flames in Constant Volume Vessel  [Not invited]

  Tsuzuki Yushi; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio

  The Proceedings of the Thermal Engineering Conference  2009  The Japan Society of Mechanical Engineers
   

  To investigate propagation of methane-air premixed flame in constant volume vessel, constant volume combustion chamber which can control turbulent characteristic and is applied by optical measurement has been developed and time-resolved measurements of CH chemiluminescence have been conducted. When flame front approaches near wall region, CH chemiluminescence vanishes and flame quenching occurs. Distance between flame front and wall when flame quenching occurs (quenching distance) is smaller in stoicheiometric condition than lean condition. Displacement speed of flame front above the ignition point decreases gradually as flame front approaches the wall, and corresponds to laminar burning velocity approximately just before flame quenching.
• DNS Approaches for Investigation of Turbulent Combustion in HCCI Engines

  Fukumoto Hiroaki; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio

  Proceedings of National Heat Transfer Symposium  2009  The Heat Transfer Society of Japan
   

  本研究では，予混合気圧縮自着火(HCCI)エンジン内における温度や当量比などの不均一性がHCCIエンジン内の乱流燃焼機構に与える影響を明らかにするために，詳細化学反応機構と輸送係数・物性値の温度依存性を考慮に入れた直接数値計算(DNS)を行った．メタン・空気予混合気における二次元DNSの結果より，乱流変動，温度変動，当量比変動の効果及びそれらの相互作用が自着火及び火炎伝播に与える影響について検討した．
• Diode Laser Absorption Sensor with Wavelength Modulation Spectroscopy for Combustion Control

  Shimura Masayasu; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio

  Proceedings of National Heat Transfer Symposium  2009  The Heat Transfer Society of Japan
   

  本研究では，H₂O分子を計測化学種として，波長変調分光法の一種である2f法を採用した半導体レーザ吸収分光センサーを構築し，二次燃料噴射により振動燃焼を制御可能なスワール型燃焼器に適用した．再循環領域の燃焼器底面に比較的近い領域において温度計測を行った場合，燃焼器内の圧力変動の支配的な周波数に対応した温度変動を計測可能であるとともに二次燃料噴射による燃焼状態の変化を検出可能であり，波長変調分光法を用いた半導体レーザ吸収分光センサーが乱流燃焼場の燃焼制御用センサーとして有効であることを明らかにした．
• Dynamics of a Local Flame Element in Turbulent Jet Flames

  yamawaki komei; seo takehiko; tanahashi mamoru; miyauchi toshio

  Proceedings of National Heat Transfer Symposium  2009  The Heat Transfer Society of Japan
   

  本研究では，高速せん断流内における乱流火炎の形成過程を明らかにするために，大規模計算機システムを用いて，詳細化学反応機構と輸送係数・物性値の温度依存性を考慮に入れた乱流噴流火炎の直接数値計算を行った．計算対象は高速な未燃ガスと保炎用の既燃ガスにより形成される二次元せん断流であり，燃料には水素・空気予混合気を用いた．数値解析の結果より，層流火炎と比較することで，せん断層の平均流速および火炎面における乱流強度の熱発生率に対する影響を検討した．
• バイオ液体燃料噴霧の燃焼特性に関する研究—平均粒径がすす生成特性に及ぼす影響—  [Not invited]

  赤間和樹; 林潤; 赤松史光; 瀬尾健彦; 橋本望; 西田啓之

  燃焼シンポジウム講演論文集  2008/11
• 637 Direct Numerical Simulation of High Reynolds Number H_2/Air Turbulent Premixed Flame  [Not invited]

  TANAKA Shoichi; SATO Makoto; SEO Takehiko; TANAHASHI Mamoru; MIYAUCHI Toshio

  The Proceedings of The Computational Mechanics Conference  2008  The Japan Society of Mechanical Engineers
   

  The effects of turbulence characteristics on local flame structure and the fractal feature of flame front are investigated by direct numerical simulation (DNS) of hydrogen-air turbulent premixed flames propagating in three-dimensional homogeneous isotropic turbulence at high Reynolds number. Flame peninsulas towards unburned mixture are frequently observed and tend to diminish due to the heat loss to surrounding low temperature unburned mixture. Multi-layer structure in large scales is created by flame folding and connections. Even for hydrogen-air premixed flames, local extinctions occur at the edge of the corrugated flame front. The fractal characteristics of the flame front are also investigated and strong correlation between the inner cutoff in Kolmogorov length unit and the ratio of the diameter of coherent fine scale eddy to the laminar flame thickness is shown.
• 635 Investigation of Turbulence Structure by Huge DNS of Homogeneous Isotropic Turbulence at High Reynolds Number  [Not invited]

  KUBOTA Taisuke; SATO Makoto; SEO Takehiko; TANAHASHI Mamoru; MIYAUCHI Toshio

  The Proceedings of The Computational Mechanics Conference  2008  The Japan Society of Mechanical Engineers
   

  To investigate statistics of the clusters of coherent fine scale eddies, direct numerical simulation databases of homogeneous isotropic turbulence up to Re_λ =344.1 have been analyzed. To measure the length scale of the clusters quantitatively, PDF variance, which is based on deviations of the concentration PDF (probability density function) of the coherent fine scale eddy from that of an uniform field, has been introduced. The concentration measure reveals that the mean distance of the coherent fine scale eddies is Taylor micro scale and the size of the cluster of the strong coherent fine scale eddies is about the integral length scale.
• Investigation of 3-Dimensional Flame Structures of Turbulent Premixed Flames by Simultaneous Dual-Plane CH PLIF and Single-Plane OH PLIF  [Not invited]

  UEDA Takashi; SHIMURA Masayasu; SEO Takehiko; TANAHASHI Mamoru; MIYAUCHI Toshio

  日本流体力学会年会講演論文集  2008  日本流体力学会
   

  To investigate 3-dimensional flame structures of turbulent premixed flame, dual-plane planar laser induced fluorescence (PLIF) of CH radical has been developed. The newly-developed dual-plane CH PLIF has been combined with single-plane OH PLIF and stereoscopic particle image velocimetry (SPIV) to clarify the relation between flame geometry and turbulence characteristics. The laser sheets for OH PLIF and SPIV measurement are located at the center of two planes for CH PLIF, where the separation between these two CH planes is selected to 500μm. The measurement was conducted in relatively high Reynolds number turbulent jet premixed flame. The experimental results show that various 3-dimensional flame structures such as the handgrip structure, which has been shown by DNS, are included in high Reynolds number turbulent premixed flame. It was shown that the simultaneous measurement containing newly-developed dual-plane CH PLIF is useful for investigating the 3-dimensional flame structure.
• Fine Scale Structure and Fractal Geometry of Scalar Mixing at High Schmidt Numbers in Turbulence  [Not invited]

  ISHIMOTO Sachinori; SATO Makoto; SEO Takehiko; TANAHASHI Mamoru; MIYAUCHI Toshio

  日本流体力学会年会講演論文集  2008  日本流体力学会
   

  Direct numerical simulations (DNS) of temporally developing turbulent mixing layer with scalar transport have been conducted to investigate the fine scale structure and the fractal geometry of scalar surfaces in turbulence. To investigate Schmidt number (S_C) effects on the turbulent scalar mixing, DNSs of turbulent scalar transport up to S_C=30.0 have been conducted for moderate Reynolds number. For high S_C, two fractal dimensions can be defined. The first fractal can be observed in relatively large scales. The dimension of the first fractal coincides with that of moderate S_C number case in the inertial subrange and is around 2.5. The second fractal dimension can be defined in small scales and shows larger values (about 2.8), which denotes self-similarity of scalar surfaces smaller than the Kolmogorov length. The inner cutoff of the second fractal reaches to about 10 times Batchelor length scale for high S_C.
• A Study of a Pellet Catalytic Combustor for a Small Scale Generation System using Near Infrared Ray Irradiation  [Not invited]

  The 7th JSME-KSME Thermal and Fluids Engineering Conference  2008
• Development of a Pellet Catalytic Combustor for a Small Scale Generation System using Near Infrared Ray Irradiation  [Not invited]

  The 2nd International Forum on Heat Transfer  2008
• Diode Laser Absorption Sensor with 2f Detection for Combustion Control by Secondary Fuel Injection  [Not invited]

  The 7th World Conference on Experimental Heat Transfer, Fluid Mechanics and Thermodynamics  2008
• Soot Formation Characteristics of Bio-liquid Fuel Spray Flames : Influence of the Fuel Type on Soot Generation Characteristic  [Not invited]

  AKAMA Kazuki; HAYASHI Jun; SEO Takehiko; AHN Chulju; AKAMATSU Fumiteru; HASHIMOTO Nozomu; NISHIDA Hiroyuki

  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  2007/12
• 対向流場におけるパームメチルエステル噴霧火炎中のすす生成特性に関する研究  [Not invited]

  林潤; 赤間和樹; 赤松史光; AHN Chulju; 瀬尾健彦; 橋本望; 西田啓之

  燃焼シンポジウム講演論文集  2007/11
• Effect of Mean Droplet Size of Liquid Fuel Spray on Soot Formation  [Not invited]

  The 4th International Conference on Flow Dynamics  2007
• Effect of droplet size distribution of fuel spray on soot formation in counter flow  [Not invited]

  International Gas Turbine Congress 2007  2007
• Combustion Diagnostics of the Premixed Flame using Chemiluminescence of OH* and CH*  [Not invited]

  17th International Symposium on Transport Phenomena  2006
• 大阪府立大学・堺・風車の会における人力飛行機用プロペラの設計 (第6回スカイスポーツシンポジウム講演集)  [Not invited]

  吉岡 岳史; 内海 智仁; 瀬尾 健彦

  スカイスポ-ツシンポジウム講演集  2000  日本航空宇宙学会
  

MISC

• Study on stabilized combustion of hydrocarbon fuel/air mixture in a small disk-type combustor

  MIYADE Takayuki; KUWATA Takatoshi; SEO Takehiko; MIKAMI Masato  The Proceedings of Conference of Chugoku-Shikoku Branch  2020-  (0)  08c3  2020
• Characteristics of Sound Radiation from Outer Surface of Automobile Muffler with Steady Internal Flow.

  IREI Hiroaki; MIKAMI Masato; SEO Takehiko  The Proceedings of Mechanical Engineering Congress, Japan  2018-  (0)  J1020204  2018
• A measurement of laminar flame speed of gasoline surrogate fuel / air mixture under high pressure condition using double kernel method

  KANEKO Hirotsugu; SEO Takehiko; MIKAMI Masato  The Proceedings of Mechanical Engineering Congress, Japan  2018-  (0)  J0710105  2018
• A study of sound source location of radiated noise in a single-cylinder diesel engine with two-stage combustion

  MINATO Koki; OGUCHI Hitosi; SEO Takehiko; MIKAMI Masato  The Proceedings of Mechanical Engineering Congress, Japan  2018-  (0)  J0710303  2018
• Study on hydrocarbon blended fuels for micro-combustor with electrospray

  HANKAWA Naofumi; SEO Takehiko; MIKAMI Masato  The Proceedings of Mechanical Engineering Congress, Japan  2018-  (0)  G0600401  2018
• The effect of spray characteristics on ignitability of laser induced breakdown ignition in fuel spray

  立石 寛達; 瀬尾 健彦; 三上 真人  微粒化シンポジウム講演論文集  26-  39  -42  2017/12
• Study on spray structure of pressure swirl atomizer with swirling air flow at subatmospheric pressure

  蛭田 眞生; 瀬尾 健彦; 三上 真人  微粒化シンポジウム講演論文集  25-  52  -57  2016/12
• Study on heat and mass transfer during pyrolysis of a few kinds of pulverized coals

  Kawamoto Kouya; Yamaji Keito; Tanoue Ken-ichiro; Nishimura Tatsuo; Mikami Masato; Seo Takehiko  The Proceedings of the Thermal Engineering Conference  2016-  (0)  E122  2016
• Characteristics of Laser-induced Ignition in Liquid Ethanol Spray

  瀬尾 健彦; 石村 祐宜; 三上 真人  微粒化 = Atomization : journal of the ILASS-Japan  24-  (83)  76  -80  2015/11
• H114 Study on dependence of ratio of pulverized coal and polystyrene on its co-pyrolytic conversion

  Kasai Kazuhiro; Kawamoto Kouya; Teramoto Takahiro; Tanoue Ken-ichiro; Nishimura Tatsuo; Mikami Masato; Seo Takehiko  The Proceedings of the Thermal Engineering Conference  2015-  (0)  _H114  -1_-_H114-2_  2015
• F132 Study of the measurement technique of laminar burning velocity by Double kernel method

  Matsuo Tsubasa; Seo Takehiko; Mikami Masato  The Proceedings of the Thermal Engineering Conference  2015-  (0)  _F132  -1_-_F132-2_  2015
• Effects of ambient air pressure on the behavior of a jet fuel simulant liquid film injected though swirl injector

  永野 佑樹; 蛭田 眞生; 瀬尾 健彦  日本航空宇宙学会西部支部講演会講演集  4p  2015
• The influence of kinematic viscosity of a jet fuel simulant liquid on its breakup process at low pressure

  神田 智行; 永野 佑樹; 瀬尾 健彦  微粒化シンポジウム講演論文集  23-  17  -22  2014/12
• A STUDY OF BREAKUP PROCESS OF A JET FUEL SIMULANT LIQUID AT LOW PRESSURE (The 16th Conference of ILASS-Asia)

  KANDA Tomoyuki; SEO Takehiko; MIKAMI Masato  微粒化シンポジウム講演論文集  22-  171  -174  2013/12
• The effect of ethanol spray concentration on laser-induced breakdown ignition

  石村 祐宜; 瀬尾 健彦; 三上 真人  微粒化シンポジウム講演論文集  22-  469  -472  2013/12
• C124 Experimental study on multi-jet-mode electrospray

  HATAKEDA Naoyuki; MUNIR F.A.; SEO Takehiko; MIKAMI Masato  The Proceedings of the Thermal Engineering Conference  2013-  (0)  79  -80  2013
• A115 Experimental Study on Flame-spread Characteristics of Fuel Droplet-cloud Elements by TFP Method

  WATARI Hidetaka; HIROSE Tsutomu; SEO Takehiko; MIKAMI Masato  The Proceedings of the Thermal Engineering Conference  2013-  (0)  9  -10  2013
• G061062 Pyrolysis experiment of pulverized coal

  MATSUURA Hiroki; MURATA Shoma; NISHIMURA Tatsuo; TANOUE Kenichiro; MIKAMI Masato; SEO Takehiko  The Proceedings of Mechanical Engineering Congress, Japan  2013-  (0)  _G061062  -1-_G061062-4  2013
• W071002 An Attempt of developing laser-induced ignition technique : Characteristics of laser-induced ignition in liquid fuel spray

  SEO Takehiko  The Proceedings of Mechanical Engineering Congress, Japan  2013-  (0)  _W071002  -1-_W071002-3  2013
• Study of the fire extinguishing mechanism of water spray on counterflow diffusion flame

  TADO Takafumi; SEO Takehiko; MIKAMI Masato  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  21-  215  -220  2012/12
• Study on role of droplet in characteristics of laser-induced plasma generation in spray : Effect of droplet position in spray

  SEO Takehiko; HISATOMI Yasuhiro; MIKAMI Masato  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  21-  221  -224  2012/12
• Effects of mean droplet diameter of water spray on extinction characteristics of heptane spray diffusion flame in counterflow

  TADO Takafumi; SASONGKO Mega Nur; SEO Takehiko; MIKAMI Masato  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  20-  167  -171  2011/12
• Experimental study on characteristics of laser-induced plasma generation in water mist

  SEO Takehiko; HISATOMI Yasuhiro; MIKAMI Masato  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  20-  172  -175  2011/12
• A study on local flame-spread-limit distance of n-decane droplet cloud element and its dependence on flame-spread direction in microgravity

  HIROSE Tsutomu; SEO Takehiko; MIKAMI Masato; KIKUCHI Masao  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  20-  93  -97  2011/12
• Activity Report of Research Team on Combustion Dynamics of Fuel Droplets

  Kikuchi Masao; Yamamoto Shin; Umemura Akira; Kobayashi Hideaki; Ogami Yasuhiro; Nomura Hiroshi; Mikami Masato; Seo Takehiko; Moriue Osamu; Shinjo Junji  宇宙利用シンポジウム: 第27回: 平成22年度 = Space Utilization Research, Vol. 27 2011: Proceedings of The Twenty-seventh Space Utilization Symposium  (27)  29  -30  2011/03
• Dynamics of a Local Flame Element in Turbulent Jet Flames

  yamawaki komei; seo takehiko; tanahashi mamoru; miyauchi toshio  Proceedings of National Heat Transfer Symposium  2009-  (0)  62  -62  2009
• Diode Laser Absorption Sensor with Wavelength Modulation Spectroscopy for Combustion Control

  Shimura Masayasu; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio  Proceedings of National Heat Transfer Symposium  2009-  (0)  34  -34  2009
• DNS Approaches for Investigation of Turbulent Combustion in HCCI Engines

  Fukumoto Hiroaki; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio  Proceedings of National Heat Transfer Symposium  2009-  (0)  32  -32  2009
• A114 Propagation of Methane-Air Premixed Flames in Constant Volume Vessel

  Tsuzuki Yushi; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio  The Proceedings of the Thermal Engineering Conference  2009-  (0)  7  -8  2009
• A123 Investigation of Local Extinction Mechanism by Direct Numerical Simulation of Methane-Air Turbulent Premixed Flame

  Yamaguchi Takuya; Shimura Masayasu; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio  The Proceedings of the Thermal Engineering Conference  2009-  (0)  13  -14  2009
• F0701(2) 複数化学種PLIFとステレオPIVの同時計測による乱流予混合火炎の構造解明([F0701]光に着目した燃焼現象の計測法,先端技術フォーラム)

  志村 祐康; 瀬尾 健彦; 店橋 護; 宮内 敏雄  年次大会講演資料集  2009-  (0)  179  -180  2009
• Analysis of Aerodynamic Sound Source by Time-Resolved Stereoscopic PIV

  OBANA Koichi; SEO Takehiko; SHIMURA Masayasu; TANAHASHI Mamoru; MIYAUCHI Toshio  日本流体力学会年会講演論文集  2009-  31  -31  2009
• Combustion Dynamics and NOx Emission of a Turbulent Swirl Stabilized Combustor with Secondary Fuel Injection :

  Rouzbeh Riazi; Shimura Masayasu; Seo Takehiko; Tanahashi Mamoru; Miyauchi Toshio  日本流体力学会年会講演論文集  2009-  86  -86  2009
• バイオ液体燃料噴霧の燃焼特性に関する研究—平均粒径がすす生成特性に及ぼす影響—

  赤間和樹; 林潤; 赤松史光; 瀬尾健彦; 橋本望; 西田啓之  燃焼シンポジウム講演論文集  46th-  394-395  2008/11
• 811 Development of a Catalytic Combustor for a Small Scale Generation System using Near Infrared Ray Irradiation

  OHMURA Go; KEIDA Tatsuya; SEO Takehiko; AHN Chulju; AKAMATSU Fumiteru; SHIBAHARA Masahiko  関西支部講演会講演論文集  2008-  (83)  "8  -11"  2008/03
• The Effect of Heat Loss on Methane/Air Lean Premixed Combustion at High Pressure

  SEO Takehiko; SAWANAKA Yusuke; HAYASHI Jun; AKAMATSU Fumiteru  日本流体力学会年会講演論文集  2008-  362  -362  2008
• A Study of a Pellet Catalytic Combustor for a Small Scale Generation System using Near Infrared Ray Irradiation

  OHMURA Go; KEIDA Tatsuya; SEO Takehiko; AHN Chulju; AKAMATSU Fumiteru; SHIBAHARA Masahiko  Proceedings of National Heat Transfer Symposium  2008-  (0)  115  -115  2008
• Fine Scale Structure and Fractal Geometry of Scalar Mixing at High Schmidt Numbers in Turbulence

  ISHIMOTO Sachinori; SATO Makoto; SEO Takehiko; TANAHASHI Mamoru; MIYAUCHI Toshio  日本流体力学会年会講演論文集  2008-  170  -170  2008
• Investigation of 3-Dimensional Flame Structures of Turbulent Premixed Flames by Simultaneous Dual-Plane CH PLIF and Single-Plane OH PLIF

  UEDA Takashi; SHIMURA Masayasu; SEO Takehiko; TANAHASHI Mamoru; MIYAUCHI Toshio  日本流体力学会年会講演論文集  2008-  364  -364  2008
• 635 Investigation of Turbulence Structure by Huge DNS of Homogeneous Isotropic Turbulence at High Reynolds Number

  KUBOTA Taisuke; SATO Makoto; SEO Takehiko; TANAHASHI Mamoru; MIYAUCHI Toshio  The Proceedings of The Computational Mechanics Conference  2008-  (0)  814  -815  2008
• 637 Direct Numerical Simulation of High Reynolds Number H_2/Air Turbulent Premixed Flame

  TANAKA Shoichi; SATO Makoto; SEO Takehiko; TANAHASHI Mamoru; MIYAUCHI Toshio  The Proceedings of The Computational Mechanics Conference  2008-  (0)  818  -819  2008
• Investigation of Combustion Synthesis of Oxide Particles by Flash Boiling Atomization

  SASAKI Koji; ODA Toshiharu; HAYASHI Jun; SEO Takehiko; AHN Chulju; SHIBAHARA Masahiko; AKAMATSU Fumiteru  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  16-  379  -382  2007/12
• Soot Formation Characteristics of Bio-liquid Fuel Spray Flames : Influence of the Fuel Type on Soot Generation Characteristic

  AKAMA Kazuki; HAYASHI Jun; SEO Takehiko; AHN Chulju; AKAMATSU Fumiteru; HASHIMOTO Nozomu; NISHIDA Hiroyuki  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  16-  (0)  96  -99  2007/12
• 対向流場におけるパームメチルエステル噴霧火炎中のすす生成特性に関する研究

  林潤; 赤間和樹; 赤松史光; AHN Chulju; 瀬尾健彦; 橋本望; 西田啓之  燃焼シンポジウム講演論文集  45th-  414-415  2007/11
• Effect of Droplet Size Distribution of Fuel Spray on Soot Formation in Counterflow

  HAYASHI Jun; KOMADA Yasuyuki; SEO Takehiko; AHN Chulju; AKAMATSU Fumiteru  微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization  15-  189  -192  2006/12
• 1226 Correlation between Local Temperature and Chemiluminescence by Contact-Less Simultaneously Measurements in Laminar Premixed Flames

  SEO Takehiko; AKAMATSU Fumiteru; SHIBAHARA Masahiko; KATSUKI Masashi  関西支部講演会講演論文集  2005-  (80)  "12  -49"-"12-50"  2005/03
• 大阪府立大学・堺・風車の会における人力飛行機用プロペラの設計 (第6回スカイスポーツシンポジウム講演集)

  吉岡 岳史; 内海 智仁; 瀬尾 健彦  スカイスポ-ツシンポジウム講演集  6-  71  -74  2000

Awards & Honors

• 2020/12 日本燃焼学会 第58回燃焼シンポジウムベストプレゼンテーション賞
   定容容器を用いた高温高圧環境下における火炎振動とエンドガスの自着火がノック強度に与える影響 japan_society 

  受賞者: 常藤飛鳥;西村凌平;瀬尾健彦;三上真人
• 2020/10 ILASS-Asia Best Paper Award in the 21st Annual Conference on Liquid Atomization and Spray Systems - Asia
   Study on the appearance of cool flame in flame spread over fuel droplets at high pressure in microgravity 

  受賞者: Yuto CHIKAMI;Kodai MATSUMOTO;Takehiko SEO;Masato MIKAMI
• 2014/12 日本燃焼学会 日本燃焼学会論文賞
   Combustion of gaseous and liquid fuels in meso-scale tubes with wire mesh 

  受賞者: 三上真人;前田敬之;松井啓一郎;瀬尾健彦;Lilis Yuliati
• 2013/03 日本エネルギー学会 日本エネルギー学会奨励賞
   

  受賞者: 瀬尾健彦
• 2012/12 日本液体微粒化学会 第12回写真コンテスト特選
   

  受賞者: 神田智行;瀬尾健彦;三上真人

Research Grants & Projects

• 冷炎を考慮した燃え広がり定義拡張とエンジン用複雑系混相燃焼への展開

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2021/04 -2024/03 

  Author : 三上 真人; 瀬尾 健彦

   

  本研究の目的は，代表研究者として行った宇宙実験「Group Combustion」から得られた群燃焼発現限界に関わる「問い」においてキーとなる「冷炎」に注目し，これまで熱炎にのみ注目して捉えられてきた液滴間燃え広がりに冷炎を考慮することで，燃え広がりの定義の拡張を行うことである． 2021年度には，大気圧において液滴群要素（干渉燃焼用二液滴と燃え広がり確認用一液滴）において，燃え広がり確認用液滴における冷炎発生条件について，「Group Combustion」実験結果の再吟味，山口大学の0.9s落下実験施設における微小重力実験による確認を行った．冷炎発生の確認を，蒸発速度をもとに行うだけでなく，昨年度までに開発した近赤外カメラを用いたTFP法による温度計測により行うとともに，本年度新たに中赤外カメラを用いた燃焼生成物による中赤外発光分布計測によっても行った． 以上と並行して，高圧における燃え広がりにおける予蒸発の影響，干渉効果を組み込んだパーコレーションモデル計算，予蒸発を考慮したパーコレーション計算検討も進めた．
• Deep understanding of elementary processes through microgravity science and application to dispersed phase combustion physics for aero engine

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2018/04 -2021/03 

  Author : Mikami Masato

   

  The objective of this research is to study the role of cool flame in the flame spread over droplets. The cool flame would be important in the phenomena near the group-combustion-excitation limit observed in the space-based experiments conducted our research group. We further investigated the results of flame spread over randomly distributed droplet clouds in the space-based experiments and analyzed the anomalous combustion phenomena in detail. The results for the droplet-cluster array was also investigated. They suggest that the cool flame appears in the anomalous combustion phenomena. Furthermore, we conducted flame-spread experiments in a drop facility and measured temperature around the droplet existing outside the flame-spread limit using the TFP method using a near-infrared camera. They showed that the cool flame appears in the flame spread within a narrow range of the droplet-spacing condition.
• Study of direct ignition method for fuel spray using laser-induced breakdown plasma

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2017/04 -2020/03 

  Author : Takehiko Seo

   

  In order to reliably ignite the fuel spray using laser beam, it is necessary to clarify the ignition mechanism in the fuel spray. In this study, we considered that the fuel droplet size and density of the fuel droplets around the ignition position and the behavior of the droplets affect the propriety of ignition. As a result, the effects of fuel droplet size and density on the success or failure of ignition could not be confirmed. It is known that a donut-shaped high temperature area is formed in laser-induced breakdown ignition, but ignition tends to fail when such a flow occurs. It was found that this flow needs to be actively controlled when the spray is ignited.
• 高効率ガソリンエンジンのためのスーパーリーンバーン研究開発

  科学技術振興機構：戦略的イノベーション創造プログラム（ＳＩＰ）革新的燃焼技術

  Date (from‐to) : 2014/10 -2019/03 

  Author : 三上真人; 瀬尾健彦
• Formulation of dispersed phase combustion physics for aero engine: from low-pressure combustion in high-altitute relight operation to high-pressure combustion in steady operation of engine

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2015/04 -2018/03 

  Author : Mikami Masato; KIKUCHI Masao; NOMURA Hiroshi; SAPUTRO Herman; SANO Narita; MOTOMATSU Naoya; YOSHIDA Yasuko; IWAI Kentaro; NAGATA Kentaro; UNEYAMA Ryo

   

  This research conducted microgravity experiments of flame spread over droplet-cloud elements and randomly distributed droplet clouds in a wide pressure range in order to improve understanding of the flame spread and group-combustion excitation in fuel sprays under high-altitude relight condition of aero engines. The experiments elucidated the effects of droplet diameter ratio, local droplet interaction and ambient pressure. The results show that the thermal conduction from a burning droplet to the next unburned droplet plays an important role and the burning lifetime of the base droplet controls the flame-spread limit. Anomalous flame-spread behavior was observed over 1.5 MPa and near the group-combustion-excitation limit in randomly distributed droplet clouds. These phenomena should be elucidated in future researches.
• Development of regenerative micro-spray combustion system with a micro-plasma actuator

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

  Date (from‐to) : 2014/04 -2016/03 

  Author : Mikami Masato; OGAWARA Kakuji; MINAMI KAZUYUKI; SEO Takehiko; Fudhail Bin Abdul Munir; HATAKEDA Naoyuki; TOKUMASA Tsuyoshi

   

  We have developed a wire mesh by a cylindrical micro-plasma actuator which supplies ambient air to a narrow tube combustor and found a condition that the flame is stabilized behind the mesh. We have numerically examined the combustor structure which enhances heat recirculation from the burned gas to the unburned gas directly or indirectly and discussed appropriate structures of liquid-fueled combustor.
• Elucidation of the physical characteristics of Laser-induced ignition of the fuel spray and approach to establishment of an ignition method

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

  Date (from‐to) : 2013/04 -2016/03 

  Author : SEO Takehiko

   

  Laser-induced ignition that is the non-contact ignition method is a promising technology for spark ignition engine. A lot of researches about laser-induced ignition and breakdown had been conducted. However, gas fuel such as methane were used in these researches. Considering an application to the SI engine, it is important to clarify the characteristics of ignition of liquid fuel spray and its mechanisms. Laser-induced breakdown and ignition of ethanol spray were studied using a high-pulse energy Nd:YAG laser. Schlieren image of flame kernels and plasma were taken by high-speed CMOS camera. Some flame kernels are formulated around plasma. The probabilities of the breakdown and ignition occurrence were determined. Based on these findings, the possibility of multi-point ignition of fuel spray with a low energy single-shot laser beam was suggested.
• Formulation of dispersed phase combustion physics at low pressure for evaluation of engine high-altitute relight performance

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

  Date (from‐to) : 2012/04 -2015/03 

  Author : MIKAMI Masato; SEO Takehiko; KIKUCHI Masao; MORIUE Osamu

   

  This research conducted microgravity experiments of flame spread over fuel-droplet arrays at a low pressure in order to improve understanding of the flame spread in fuel sprays under high-altitude relight condition of jet engines. The results show that both the flame-spread rate and flame-spread limit distance at the low pressure are greater than those at atmospheric pressure. The pressure effect on the flame-spread rate was discussed considering some elementary processes, such as droplet heating and thermal diffusion. The thermal diffusion speed is inversely proportional to the pressure. The pressure effect on the flame-spread limit distance was discussed considering transient process of high-temperature region around a burning droplet. The maximum radius of the outer edge of the high-temperature region is proportional to -1/3 power of the ambient pressure. Group combustion occurrence was also demonstrated with a percolation model considering the flame-spread limit.
• Development of Micro LPP Combustion Technique Using Electrospray

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

  Date (from‐to) : 2009 -2011 

  Author : MIKAMI Masato; SEO Takehiko; TANOUE Kenichiro; MINAMI Kazuyuki

   

  Many researchers have studied micro combustors, which burn fuels in a small space and are used as very small power generators with high energy density or small heaters with high efficiency. In order to use liquid fuels, whose energy density is relatively high, in micro combustors, it is necessary to complete vaporization of liquid fuel, mixing with air and burning in a small combustor. This research succeeded to stably burn liquid fuels in a narrow glass tube.
• 高圧条件下における乱流燃焼機構の解明

  その他の研究制度

  Date (from‐to) : 2008
• レーザ着火における着火特性に関する研究

  その他の研究制度

  Date (from‐to) : 2008
• -

  The Other Research Programs

Teaching Experience

Exercise in Aerospace and Thermal Energy EngineeringExercise in Aerospace and Thermal Energy Engineering YAMAGUCHI UNIVERSITY
Mechanical Engineering LaboratoryMechanical Engineering Laboratory YAMAGUCHI UNIVERSITY

Committee Membership

• 2018/04 -2019/12   ILASS Asia 2019 Organizing Committee   Vice Chair

Other link

researchmap

https://researchmap.jp/Takehiko_Seo