Experiments were conducted using propane for the characteristics of the gaseous jet in the direct injection gasoline engine and the experiment using the propane. The concentration distribution of the propane jet when injected from the gas injector into the pressure vessel of the high pressure field is measured by the laser induced fluorescence method. The flow state was measured using the particle image correlation method. Therefore, numerous vortex structures were observed at the boundary of the gaseous jet. Furthermore, when the ambient pressure was increased, the number of vortices increased and the size of the vortex became finer. Also, since the fluorescence intensity decreases along the downstream side of the jet, a vortex structure that takes in the ambient air is observed.Ⅲ.論文集

In order to visualize the actual flow inside a diesel injection nozzle at high-pressure injection, a model nozzle which has nozzle hole diameter with real size was made of sapphire. Using the transparent nozzle and three kinds of fuel, the effects of the fuel properties on the internal flow in the nozzle hole were investigated. The spray characteristics were observed by high-speed shadowgraph photography under realistic conditions. As the result, the fuel which 90% distillation temperature and kinematic viscosity are low, amount of cavitation generation is increased. Therefore, the spray atomization and evaporation are promoted.Ⅲ.論文集

In this paper, it is a purpose to obtain basic information of a hydrogen jet and combustion flame characteristics of the hydrogen rotary engine. The jet characteristics of the hydrogen gas injector were measured by using the high-speed shadowgraph method. As the result, the jet penetration of the low density gas was weak. The mixing of the direction of the jet axis was disturbed for the low jet pressure. Next, the combustion flame propagation of the hydrogen rotary engine was visualized by high-speed camera system with a transparent engine. The flame propagation was fast in the hydrogen combustion. It became clear that the end gas burn quickly at upstream combustion chamber.

Cycle-resolved measurements of the fuel concentration near a spark plug in a commercial rotary engine were performed. An in situ laser infrared (IR) absorption method was developed using a spark plug sensor and a 3.392-mu m He-Ne laser as the light source. This wavelength coincided with the absorption line of hydrocarbons. The newly developed IR spark plug sensor had a higher signal-to-noise ratio than its previous version due to the optimization of its quartz lens and two optical fibers. The new sensor provided quantitative cycle-resolved fuel concentration measurements around the spark plug with a high temporal resolution. At lean preset air/fuel (A/F) ratios, fuel was mixed with the surrounding air gradually by the rotor motion in the plug hole of the rotary engine. Strong mixture inhomogeneities were measured during the compression stroke; the magnitude of these inhomogeneities decreased throughout the compression stroke. Cycle-resolved measurements were made to investigate the effects of the fuel concentration near the spark plug on the combustion characteristics of the commercial rotary engine. There was a strong correlation between the fuel concentration measured with the spark plug sensor and the combustion characteristics during the initial combustion period, which occurred faster when conditions were slightly richer than stoichiometric near the spark plug. The indicated mean effective pressure (IMEP) was slightly related to the A/F ratio near the spark plug. It was possible to measure the cycle-resolved A/F ratio near the spark plug and investigate its cycle-to-cycle fluctuations to achieve stable operation using the newly developed spark plug sensor. (c) 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

An ion current probe using a spark plug was applied to gasoline-fuelled homogeneous charge compression ignition (HCCI) combustion with hot residual gas in order to verify the possibility of using it as a combustion sensor. The ion current signal for single-cycle HCCI combustion had a simple profile and effectively one maximum value. There is a possibility that a similar ion current signal corresponding to the completed reaction can be obtained, depending on the location of the probe during HCCI combustion. The ionization reaction for HCCI combustion is affected by the chemical ionization reaction with heat release, and there is a possibility that the ion current can be used to detect heat release corresponding to the chemical ionization reaction. A strong correlation between the timing of the integrated ion current and the timing of the mass fraction burned is observed. The timing of the mass fraction burned is assumed from the timing of the integrated ion current, and the mass fraction burned (up to 70 per cent) can be determined, even if the engine driving condition changes within the scope of the test. There is a correlation between the timing of the maximum ion-current and the maximum rate of heat release, and there is a possibility that the maximum value of the rate of heat release can be inferred by detecting the timing of the maximum ion current. There is a correlation between the timing of the maximum ion current and the timing of the maximum pressure at each cycle. Therefore, it may be possible to monitor the variation of the HCCI combustion phasing. © IMechE 2005.

Effects of squish area location on tumble and squish flow were investigated to control the knock in an SI engine. For the exhaust squish piston, tumble flow is collapsed by the exhaust squish clearance during the compression stroke, so that the compression-squish flow is strong. For the intake squish piston, tumble flow impinges on the edge of squish area and the induction of it into the squish area is controlled. The compression-squish flow is weakened and reverse-squish flow grows strong. This led to realization of a high heat release at late stage combustion. Simultaneously, the decrease of cycle-by-cycle variation of initial burn is realized. Consequently, knocking is controlled compared with a flat piston. (C) 2002 Society of Automotive Engineers of Japan, Inc. and Elsevier Science B.V. All rights reserved.

A pancake-type constant-volume combustion chamber was used to investigate the combustion and NO_χ emission characteristics of propane-air and hydrogen-air mixtures under various charge stratification patterns, which were obtained by variations of injected mixture concentration and ignition spark timing. A planar laser-induced nitrogen dioxide fluorescence technique was applied to measure the mixture distribution in the test chamber. The results show that under the rich side of overall excess air ratio, the combustion speed of the homogeneous mixture was slightly faster than that of the stratified mixture. When the rich mixture was near the spark ignition point, the combustion speed was fastest under the lean side of overall excess air ratio. When the mixture concentration near the spark ignition point increased, NO_χ emissions increased under the lean side of overall excess air ratio but decreased under the rich side.

Laser-induced fluorescence from nitrogen dioxide (NO_2) as gas fuel tracer was applied to determine mixture stratification in a pancake type constant-volume combustion chamber using propane and hydrogen fuels. The second-harmonic output of a pulsed Nd : YAG laser was used as a light source for fluorescence excitation. the fluorescence images were corrected by a gated image-intensified CCD camera. The quantitative analysis of fuel concentration was made possible by the application of linearity between fluorescence intensity and NO_2 concentration at a low trace level. The stratified mixture (center-rich or center-lean) was concentrically formed in the central region of the chamber by a jet flow from a tangentially oriented port. The concentration difference in the radial direction of the chamber decreased with time from the start of injection. The rate of decrease was faster for hydrogen than for propane. After 300ms from start of injection, however, the time histories of the concentration (difference were nearly constant for both fuels regardless of overall concentration.

Planar laser-induced fluorescence (PLIF) was applied to 2-D visualization of OH radical distribution in a combustion chamber of a single-cylinder spark ignition engine. A Nd : YAG laser-pumped pulsed dye laser with frequency doubling was used to form a sheet of laser light which induced the OH X²Π→A²Σ transition. Fluorescence images of the OH radical and visible images of flames were simultaneously imaged by a pair of image-intensified CCD cameras. The OH distributions in the combustion chamber were measured under various conditions of mass burned rates, swirl rates and air-fuel ratios. The OH images were very complicated in structure compared with the visible images. The OH distributions were not only observed near the flame front but also observed in the reaction zone behind the flame front. The OH fluorescence intensity reached a peak value at the swirl rate at which the HC emission indicated a low value. Both the OH fluorescence intensity and the NO_x emission had peaks at the near-theoretical air-fuel ratio.

The size distribution of small praticles can be obtained by optical analysis of the Fraunhofer diffraction light scattered by particles. In this study, direct photographs of the diffracted light from particles or spray drops were taken using a pulsed laser and analyzed. Error due to the characteristic properties of this pulsed laser diffraction method were investigated for many groups of particles. The mean particle size was measured within an error of less than ±10%, even if the diffmacted light from particles passed through a high ambient temperature and pressure envirnment. The Fraunhofer diffraction pattern of a diesel spray in a vaporizing process was analyzed by this method to obtain the Sauter mean diameter of the spray.

The Sauter mean diameter and size distribution of a diesel spray in a vaporizing process were studied using the pulsed laser diffraction technique presented in the lst report. The Sauter mean diameter and size distribution were introduced to study the overall vaporizing phenomena of the spray. The liquids used were diesel fuel and n-Heptane. The Sauter mean diameter increased once, then decreased with an increase of the ambient temperature, under the ambient gas density, which was kept constant at a high pressure level. This change of the Sauter mean diameter was different for the evaporation rate of a fuel. The increase of the Sauter mean diameter of the n- Heptane spray occured at a lower ambient temperature condition than for the diesel fuel spray.

The new empirical equations to represent the Sauter mean diameter of a spray injected from a diesel nozzle were reported in this paper. In order to determine the new equations of the mean diameter, drop sizes of a diesel spray were analyzed by a laser diffraction technique. Liquids with different viscosities and different surface tensions were tested. The maximum injection pressure and the maximum ambient pressure were 90 MPa and 3 MPa, respectively. According to the tendencies of break-up length and drop sizes of a spray for an injection velocity and an ambient pressure, the spray formation mechanism could be divided into two categories as a function of the injection velocity and physical properties of the liquid. Finally, dimensionless analysis for each category of a spray could lead tot the empirical equations of the Sauter mean diameter.

The purpose of this study is to clarify the effect of liquid viscosity on the Sauter mean diameter and the spray angle. The spray injected by a diesel nozzle of hole type was observed by the laser diffraction technique system and the direct photography method. The tests were carried out over a wide range of injection pressures and viscosities of glycerine solution at ambient pressure of 3 MPa. With an increasing liquid viscosity, the spray angle decreases and the Sauter mean diameter gradually increases. With further increase of the Viscosity, the Sauter mean diameter suddenly increases. There is an upper limit of the viscosity to be atomized as a spray of fine droplets. At a high injection pressure, the effect of viscosity on the Sauter mean diameter still remains but the viscosity has no effect on the spray angle.

ディーゼル機関での燃料の粗悪化,高粘度化に対処するため,噴射燃料の基礎となる噴射に及ぼす粘度の影響について,レーザ回折による粒径測定および噴射角の測定を行った。ふん囲気圧力,噴射力,液体の粘度を変化させて,その影響を調べ,粘度に及ぼす微粒化の限界を示した。高圧噴射を行うと粘度が高いほど平均粒径は増加するが,噴霧角はその影響を受けないことなどがわかった。

高圧噴射弁を用いた直接水素エンジンでの水素火炎の高速撮影および燃焼圧力測定を行った．高圧水素噴射弁噴孔パターンの違いや噴射時期を変化させることで，以下の結果となった．噴射時期を遅角化していくに従って燃焼速度は速くなる，高圧水素噴射弁噴孔パターンを変えることで．，空間的不均一性の高いSingle は高濃度の水素領域を点火プラグ近傍に配置できるため燃焼が速くなる．空間的に拡がりが大きなCone, Flat にするとその効果は少なくなることなどが明らかになった．

レシプロおよびロータリエンジンを天然ガス運転した場合のエンジン性能および排気ガス性能に及ぼすCO2濃度の影響を調べた．結果を比較した．ロータリエンジンでは，逆スキシュ燃焼が効果的に働き，CO2濃度増加に対する平均有効圧力，THC，NOxの悪化は緩やかであり，CO2濃度55%でも安定した燃焼が可能である．CO2の影響は低負荷ほど顕著に表れる．また，高いCO2濃度の燃料に対し，レシプロエンジンより適用性が高いことが明らかになった．

直接駆動式高圧ガス噴射弁を用い，直接筒内水素噴射した場合の水素噴流の混合と燃焼状態を把握することを目的に，レーザシート光を用い高圧水素噴射弁の噴流特性を調べ，従来の低圧ガス噴射弁との混合過程の違いを明らかした．さらに，単筒急速圧縮エンジンを用いて，筒内水素噴射時期を変化させることで，着火時の混合状態をコントロールし，水素火炎の挙動の高速直接撮影を試みた．その結果，圧縮行程後半で水素噴流に直接噴流点火することで，希薄な燃焼条件でも高速燃焼かつ安定した燃焼が可能であることなどを明らかにした．

水素ロータリーエンジンの仕組みと特徴およびロータリーエンジンでの水素燃焼を中心にした内燃機機関へのアプリケーションについて紹介する．