研究者詳細 - 河原　伸幸

MISC - 河原　伸幸

分割表示 242 件中 201 - 220 件目／全件表示 >>

Effects of EGR and early injection of diesel fuel on combustion characteristics and exhaust emissions in a methane dual fuel engine

Eiji Tomita, Nobuyuki Kawahara, Zhenyu Piao, Ryoichi Yamaguchi

SAE Technical Papers 2002年

記述言語：英語

A dual fuel engine fueled with methane from an inlet port and ignited with diesel fuel was prepared. This study focuses on the effects of early injection and exhaust gas recirculation (EGR) on the characteristics of combustion and exhaust emissions. The injection timing was changed between TDC and 50 degrees before the TDC. In the early injection timing, smoke was never seen and hydrocarbons were smaller compared with those at the normal injection timing. However, the combustion becomes too early to obtain an appropriate torque when the equivalence ratio increases. Then, moderate EGR was very effective to force the combustion to retard with lower NOx, higher thermal efficiency and almost the same hydrocarbons and carbon monoxide. The engine operated even under the condition of stoichiometric mixture. Copyright © 2002 SAE International.

DOI： 10.4271/2002-01-2723

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Effects of EGR and early injection of diesel fuel on combustion characteristics and exhaust emissions in a methane dual fuel engine

Eiji Tomita, Nobuyuki Kawahara, Zhenyu Piao, Ryoichi Yamaguchi

SAE Technical Papers 2002年

記述言語：英語

DOI： 10.4271/2002-01-2723

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In situ fuel concentration measurement near spark plug in spark-ignition engines by 3.39 μm infrared laser absorption method

Eiji Tomita, Nobuyuki Kawahara, Sadami Yoshiyama, Akihiko Kakuho, Teruyuki Itoh, Yoshisuke Hamamoto

Proceedings of the Combustion Institute 29 ( 1 ) 735 - 741 2002年

記述言語：英語

Recently, improving the thermal efficiency and reducing the exhaust emissions of internal combustion engines have become crucial. To this end, it is important to determine the fuel concentration in the vicinity of the spark plug near the spark timing, because initial combustion affects the subsequent main combustion in spark-ignition engines. In this study, a fiber optic system linked to an optical sensor installed in the spark plug, by means of which light can pass through the combustion chamber, was developed to determine the fuel concentration near the spark plug using an IR absorption method. A He-Ne laser with a wavelength of 3.39 μm that coincides with the absorption line of hydrocarbons was used as a light source. By exchanging an ordinary spark plug for this spark plug with the optical sensor, successive measurement of fuel concentration before the spark timing near the spark plug was performed in a port-injection spark-ignition engine fueled with iso-octane under the firing condition. The effects of pressure and temperature on the molar absorption coefficient of fuel were clarified in advance. The air/fuel ratio averaged for many cycles near the spark plug with this optical system agreed with that measured with a buret, which represented the mean value averaged over a protracted period. Next, this sensor was applied to determine the air/fuel ratio quantitatively in a direct-injection gasoline engine. As a result, it was clarified that the air/fuel ratio and its standard deviation near the spark plug have a strong relationship to stable engine operation.

DOI： 10.1016/S1540-7489(02)80094-3

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Transient temperature measurement of unburned gas using optic heterodyne interferometry

N Kawahara, E Tomita, H Kamakura

LASER TECHNIQUES FOR FLUID MECHANICS 157 - 172 2002年

記述言語：英語出版者・発行元：SPRINGER-VERLAG BERLIN

Optical heterodyne interferometry was validated to measure the transient temperature of a gas by comparing the temperature history of unburned gas in a combustion chamber, caused by compression due to flame propagation, obtained by the heterodyne interferometry with temperature obtained by assuming adiabatic change. When the density of gas changes, the effective optical path length of the test beam changes with corresponding changes of the refractive index. Therefore, the temperature history of the gas can be determined by measuring the pressure and the phase shift of the interference signal. As a result, it is clearly recognized that a non-intrusive measurement in the transient gas temperature was made successfully by the optical heterodyne interferometry. The resolution of the temperature measurement is approximately 0.5 K, and is dependent upon both the sampling clock speed of the A/D converter and the length of the test section. Moreover, a polarization-preserving fiber was used to deliver the test beam to and from the test section to improve the feasibility of the system as a sensor probe. It may also be applied to other system requiring fast response density and temperature measurement of a gas, the latter necessitating a simultaneous record of transient pressure.

Web of Science

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In-situ fuel concentration measurement near spark plug in spark-ignition engines by 3.39 μM infrared laser absorption method

Eiji Tomita, Nobuyuki Kawahara, Sasdami Yoshiyama, Akihiko Kakuho, Teruyki Itoh, Yoshisuke Hamamoto

International Symposium on Combustion Abstracts of Accepted Papers 29 ( 1 ) 735 - 741 2002年

記述言語：英語

Improving thermal efficiency and reducing the exhaust emissions of internal combustion engines have become crucial. Thus, it is important to determine the fuel concentration in the vicinity of the spark plug near the spark timing because initial combustion affects the following main combustion in spark-ignition engines. A fiber optic system linked to the optical sensor installed in the spark plug, by means of which light could pass through the combustion chamber, was developed to determine the fuel concentration near the spark plug using an IR absorption method. A He-Ne laser with a wavelength of 3.39 μm coinciding with the absorption line of hydrocarbons was utilized as a light source. By exchanging an ordinary spark plug for this spark plug with the optical sensor, successive measurement of fuel concentration before the spark timing near the spark plug was carried out in a port injection spark-ignition engine fueled with isooctane under the firing condition. The air/fuel ratio averaged for many cycles near the spark plug with this optical system agreed with that measured with a buret, which represented the mean value averaged over a protracted period. This sensor was also applied to determine air /fuel ratio quantitatively in a direct injection gasoline engine. As a result, it was clarified that the air/fuel ratio and its standard deviation near the spark plug had a strong relationship to the stable engine operation. Original is an abstract.

DOI： 10.1016/S1540-7489(02)80094-3

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An Optical Sensor Instrumented in Spark Plug for In-situ Fuel Concentration Measurement in an Engine Cylinder by 3.39 mm Infrared Absorption Method,

Tomita, E, Kawahara, N, Shigenaga, M, Yoshiyama, S, Hamamoto, Y, Kakuho, A, Itoh, T, Dibble, R.W

11th Int. Symp. on Application of Laser Techniques on Fluid Mechanics 2002年

Transient Temperature Measurement of Unburned Gas in an Engine Cylinder Using Fiber-Optic Heterodyne Interferometry,

Kawahara, N, Tomita, E, Kamakura, H, Ichimiya, M

11th Int. Symp. on Application of Laser Techniques on Fluid Mechanics 2002年

In situ fuel concentration measurement near spark plug in spark-ignition engines by 3.39 μm infrared laser absorption method

Eiji Tomita, Nobuyuki Kawahara, Sadami Yoshiyama, Akihiko Kakuho, Teruyuki Itoh, Yoshisuke Hamamoto

Proceedings of the Combustion Institute 29 ( 1 ) 735 - 741 2002年

記述言語：英語出版者・発行元：Elsevier Ltd

DOI： 10.1016/S1540-7489(02)80094-3

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(2-08) Effects of Swirl Turbulent Flow Field and Inhomogeneous Concentration Field on Combustion of Fuel-Air Mixture in a Constant Volume Vessel((SI-3)S. I. Engine Combustion 3-Flow and Combustion)

KAWAHARA Nobuyuki, TOMITA Eiji, YOSHIYAMA Sadami, NISHIYAMA Atsushi, HAMAMOTO Yoshisuke

The ... international symposium on diagnostics and modeling of combustion in internal combustion engines ( 1 ) 29 - 29 2001年7月

記述言語：英語出版者・発行元：一般社団法人日本機械学会

Direct injection spark ignition (DISI) engines, which are able to achieve better thermal efficiency and higher output power simultaneously, have been developed. The DISI engine is operated unthrottled in an ultra-lean condition by distinctively stratifying the charge and by preparing a fuel-rich mixture around the spark plug. However, the effects of mixture inhomogeneity and simultaneous details of the flow field at the time of the spark on the combustion have not yet been clarified. In this research, the fundamental flame propagation and combustion characteristics of a stratified fuel-air mixture, similar to mixtures used in direct injection spark ignition (DISI) engines, were investigated. A swirling fuel-air mixture was produced in a disc-type combustion chamber by accelerating the mixture tangentially. Propane was injected into the center of the combustion chamber at an injection pressure of 0.3 MPa. The strong swirl combined with the gas injection created an axisymmetric fuel-rich mixture near the spark location and a lean mixture near the wall. The swirl, gas injection and spark timing changed the flow field, turbulence intensity, and inhomogeneity of the fuel-air mixture. The mixture was ignited at the center of the vessel. The fuel concentration distribution and the swirling flow field at the time of the spark were measured using LIF and LDV, respectively. Experimental tests were performed for various fuel distributions and different swirl flow at the ignition timing. Flame propagation and the combustion characteristics of an inhomogeneous fuel-air mixture are discussed using instantaneous flame images obtained from a high-speed video and the pressure history. Three main conclusions are drawn from this work. First, strongly swirling flow with gas injection at the center generates successive inhomogeneous fuel concentrations. By changing the period between gas injection and ignition, various gradients of inhomogeneous mixture concentrations and equivalence ratios can be obtained in the vicinity of the spark location. A stratified charge with an appropriate mixture near the spark location allows the flame to propagate and combustion to occur, even when an ultra-lean fuel-air mixture is used. Second, the stratified stoichiometric mixture in the vicinity of the spark location propagates more rapidly than in the homogeneous case with the same overall equivalence ratio, resulting in a higher rate of pressure increase and a shorter ignition delay time. Third, when stratified mixtures with the same pattern of fuel concentration but different turbulence intensities are considered, the main combustion period decreases with turbulence intensity at an overall equivalence ratio of 0.30, since the burning velocity also increases.

CiNii Article

CiNii Books

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409 レーザ干渉法による二平行円板間における予混合火炎消炎過程の温度分布計測(エンジンIII)

冨田栄二, 河原伸幸, 臼田和也

講演論文集 2001 ( 39 ) 137 - 138 2001年2月

408 3.39μmにおける炭化水素系燃料の吸光係数に及ぼす圧力・温度の影響(エンジンIII)

冨田栄二, 河原伸幸, 吉山定見, 北川和典

講演論文集 2001 ( 39 ) 135 - 136 2001年2月

401 加圧雰囲気下における非定常燃料噴霧の挙動(エンジンI)

河原伸幸, 冨田栄二, 樫村亮

講演論文集 2001 ( 39 ) 121 - 122 2001年2月

Measurement of Transient Temperature of Gas Using Fiber Optic Heterodyne Interferometer

Kawahara, N, Tomita, E, Kamakura, H

Proc. of 3rd ASPACC 2001年1月

A fiber optical heterodyne interferometry system was developed to obtain high temporal resolution temperature histories of unburned and burned gases non-intrusively. The effective optical path length of the test beam changes with the gas density and corresponding changes of the refractive index. Therefore, the temperature history of the gas can be determined from the pressure and phase shift of the interference signal. The resolution of the temperature measurement is approximately 0.5 K, and is dependent upon both the sampling clock speed of the A/D converter and the length of the test section. A polarization-preserving fiber is used to deliver the test beam to and from the test section, to improve the feasibility of the system as a sensor probe. This optical heterodyne interferometry system may also be used for other applications that require gas density and pressure measurements with a fast response time, or a transient temperature record. Copyright © 2001 Society of Automotive Engineers, Inc.

DOI： 10.4271/2001-01-1922

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ガンタイプバーナにおける噴霧のレーザ計測（噴霧クラスタと群燃焼構造）

河原伸幸, 池田裕二, 中島健

日本機械学会論文集Ｂ編 67 ( 655 ) 841 - 848 2001年

記述言語：日本語

A concept of "compound-cluster combustion" is proposed in order to investigate an applicability of group combustion theory to practical spray combustion, in which strong turbulent coherent vortex is formed and influenced spray behavior significantly. This turbulent coherent structure causes inhomogeneous droplet distribution and its population, and causes interphase exchange of properties and combustion under the effects of preferential interactions. In application of group combustion theory to practical spray combustion, these points were taken into account and phase Doppler measurement (PDA) data was analyzed : there are multiple clusters, characterized by their size and followabiliy (Stokes effect) ; clusters of different droplet sizes are produced at the same time in the flow field; the turbulent scale on cluster formation should be considered by the droplet's inter-arrival time statistics. In this research, PDA measurement with high sampling-rates and high validation- rates was carried out by optimizing the PDA set-up parameters. The integral length scale of each size cluster and the inter-arrival time statistics of the droplets can be obtained, based on the instantaneous droplet velocities as well as, but also Stokes' number, cluster size and inter-arrival time. The size-classified group combustion number is evaluated by the experimental data to demonstrate the applicability of group combustion theory. The interaction between the turbulent coherent vortex and small droplets of less than 30 μm generates essential clusters of the droplets and its combustion can be characterized by group combustion. The size of these clusters corresponds to the integral scale of the turbulent vortices. The effect of turbulent coherent structure on compound- cluster formation is examined and this effect is successfully evaluated by the Stokes effect.

DOI： 10.1299/kikaib.67.841

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光ヘテロダイン干渉法によるガス温度変化計測

河原伸幸, 冨田栄二

光アライアンス Vol.12, No.12, pp.18-21 ( 12 ) 18 - 21 2001年

Hydrogen combustion and exhaust emissions ignited with diesel oil in a dual fuel engine

Eiji Tomita, Nobuyuki Kawahara, Zhenyu Piao, Shogo Fujita, Yoshisuke Hamamoto

SAE Technical Papers 2001年

記述言語：英語

Hydrogen is expected to be one of the most prominent fuels in the near future for solving greenhouse problem, protecting environment and saving petroleum. In this study, a dual fuel engine of hydrogen and diesel oil was investigated. Hydrogen was inducted in a intake port with air and diesel oil was injected into the cylinder. The injection timing was changed over extremely wide range. When the injection timing of diesel fuel into the cylinder is advanced, the diesel oil is well mixed with hydrogen-air mixture and the initial combustion becomes mild. NOx emissions decrease because of lean premixed combustion without the region of high temperature of burned gas. When hydrogen is mixed with inlet air, emissions of HC, CO and CO2 decrease without exhausting smoke while brake thermal efficiency is slightly smaller than that in ordinary diesel combustion. In particular, both smoke and NOx are almost zero and HC is low when the injection timing is significantly advanced although the engine operation becomes unstable. Copyright © 2001 Society of Automotive Engineers, Inc.

DOI： 10.4271/2001-01-3503

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Effects of swirl turbulent flow field and inhomogeneous concentration field on combustion of fuel-air mixture in a constant volume vessel

Kawahara, N, Tomita, E, Nishiyama, A, Yoshiyama, S, Hamamoto, Y

Proc. of 5th COMODIA 2001 2001年

Combustion Characteristics of Stratified Fuel-Air Mixture with Swirl in a Constant-Volume Vessel

Nishiyama, A, Tomita, E, Kawahara, N, Hamamoto, Y, Yoshiyama, S

Proc. of 3rd ASPACC 2001年

808 定容容器内一次元層状燃料濃度場を伝播する火炎の観察(O.S.5-2 基礎燃焼)(O.S.5 次世代エンジンのための燃焼制御と新技術)

冨田栄二, 河原伸幸, 浜本嘉輔

講演論文集 5 ( 2 ) 247 - 248 2000年10月