研究者詳細 - 小橋　好充

論文 - 小橋　好充

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Numerical simulation of evaporating sprays of ethanol fuel blends 査読

Yoshimitsu Kobashi, Yusuke Kimoto, Satoshi Kato

SAE Technical Papers 11 2013年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Ethanol is a promising alternative to fossil fuels because it can be produced from biomass resources that are renewable. Due to the amount of production, however, the usage would be limited to blends with other conventional fuels. Ethanol-fuel blends are azeotropic and have unique vaporization characteristics different from blends composed of aliphatic hydrocarbons, so that the present study developed a numerical scheme which takes into account the vapor-liquid equilibrium of azeotrope in order to update the author's original version of the multi-component fuel CFD model and to evaluate the effect of mixing ethanol into gasoline on the evaporation process. The numerical simulation was implemented for evaporating sprays of ethanol-n-heptane blends, which are injected through a single hole nozzle. In addition to the vapor-liquid equilibrium, the effect of the latent heat of vaporization was investigated. The result clearly shows the effect of azeotropic phenomenon on the evaporation process while indicating that the latent heat of vaporization plays more significant role on the evaporation for the case of higher mixing fraction of ethanol. Copyright © 2013 SAE International and Copyright © 2013 KSAE.

DOI： 10.4271/2013-01-2552

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SPRAY VAPORIZATION AND IGNITION CHARACTERISTICS IN DUAL-COMPONENT MIXED FUELS 査読

Chang-Eon Lee, Seungro Lee, Masanori Okada, Masashi Matsumoto, Yoshimitsu Kobashi, Jiro Senda

ATOMIZATION AND SPRAYS 23 ( 2 ) 141 - 164 2013年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：BEGELL HOUSE INC

In this study, the ignition characteristics and vaporization characteristics of a dual-component mixed fuel composed of low boiling temperature (LBT) fuels were investigated experimentally in terms of fuel composition and mass fraction (Y-LBT) using a constant volume combustion vessel. For this purpose, two groups of mixed fuels were tested: The first group was a mixture of the high boiling temperature (HBT) fuel nC13 as the base fuel and various LBT fuels with similar BTs ranging from 350 to 380 K but with different ignition temperatures (ITs), and second group was a mixture of HBT fuel and various LBT fuels with ITs similar to the IT of nC13 but different BTs. The results indicate that although the type and mass fraction of the LBT fuels in the dual-component mixed fuels were varied, small changes in density did not produce changes in the spray behavior of the fuels, which is described by the spray tip penetration under the no-combustion condition. The ignition delay times for nearly all of the mixed fuels were the same as the delay time of pure nC(13) below Y-LBT = 0.5; however, the ignition delay times rapidly increased with the characteristics of the boiling curve diagrams of the mixed fuels.

DOI： 10.1615/AtomizSpr.2013007513

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直接噴射方式におけるノズル内キャビテーションが噴霧特性に及ぼす影響（第2報：供試液体中の溶存空気濃度を変化させた際の衝撃加速度と噴流の関係) 査読

松本雅至, 井上欣也, 安富友香, 小橋好充, 松村恵理子, 神田睦美, 千田二郎

日本機械学会論文集(B編) 79 ( 806 ) 2160 - 2169 2013年

二成分混合燃料噴霧による圧縮着火機関の圧力上昇率およびエミッションの低減査読

前川浩輝, 小橋好充, 加藤聰, 千田二郎

自動車技術会論文集 43 ( 6 ) 1263 - 1268 2012年11月

Simultaneous Reduction of Pressure Rise Rate and Emissions in a Compression Ignition Engine by Use of Dual-Component Fuel Spray 査読

Yoshimitsu Kobashi, Hiroki Maekawa, Satoshi Kato, Jiro Senda

SAE International Journal of Fuels and Lubricants 5 ( 3 ) 1404 - 1413 2012年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

Ignition, combustion and emissions characteristics of dual-component fuel spray were examined for ranges of injection timing and intake-air oxygen concentration. Fuels used were binary mixtures of gasoline-like component i-octane (cetane number 12, boiling point 372 K) and diesel fuel-like component n-tridecane (cetane number 88, boiling point 510 K). Mass fraction of i-octane was also changed as the experimental variable. The experimental study was carried out in a single cylinder compression ignition engine equipped with a common-rail injection system and an exhaust gas recirculation system. The results demonstrated that the increase of the i-octane mass fraction with optimizations of injection timing and intake oxygen concentration reduced pressure rise rate and soot and NOx emissions without deterioration of indicated thermal efficiency. Numerical investigation into the pressure rise rate reduction mechanism was also performed by use of a multi-component fuel model developed by the authors. The calculated result showed that the pressure rise rate was reduced due to the difference in the vapor concentrations between two components which have difference reactivity. © 2012 SAE Japan.

DOI： 10.4271/2012-32-0031

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Effects of Fuel Composition on Flame Lift-off Length and Pollutant Formation in Dual-component Fuel Spray 査読

Masanori Okada, Daisuke Shigetomi, Masashi Matsumoto, KOBASHI, YOSHIMITSU, Jiro Senda

The Proceedings of the Eighth International Conference on Modeling and Diagnostics for Advanced Engine Systems (COMODIA) 323 - 328 2012年7月

着火性の異なる燃料の二段噴射により形成される混合気分布がPCCI燃焼の着火・燃焼過程に及ぼす影響査読

松本雅至, 岸裏雅登, 小橋好充, 松村恵理子, 千田二郎

自動車技術会論文集 43 ( 4 ) 875 - 880 2012年7月

Chemical Thermodynamics Modeling of Vaporization and Ignition Processes in Dual-component Fuel Spray 査読

Masashi Matsumoto, Chang Eon-Lee, Daisuke Shigetomi, Masanori Okada, KOBASHI, YOSHIMITSU, Jiro Senda

The Proceedings of the Eighth International Conference on Modeling and Diagnostics for Advanced Engine Systems (COMODIA) 635 - 640 2012年7月

各種アルコール燃料の混合がバイオディーゼル燃料の燃焼特性に及ぼす影響査読

松浦貴, 小橋好充, 桑原一成, 千田二郎

自動車技術会論文集 43 ( 2 ) 455 - 460 2012年3月

二成分混合燃料噴霧の着火・燃焼機構と燃焼制御性に関する数値解析査読

小橋好充, 藤森健太, 前川浩輝, 加藤聰, 川野大輔, 千田二郎

自動車技術会論文集 43 ( 1 ) 123 - 128 2012年1月

二燃料の混合気濃度と燃焼位相が圧縮着火機関の性能・排気特性に及ぼす影響査読

小橋好充, 田中大二郎, 丸小鉄平, 加藤聰

日本機械学会論文集(B編) 78 ( 788 ) 939 - 947 2012年

直接噴射方式におけるノズル内キャビテーションが噴霧特性に及ぼす影響（第1報：噴射圧力および供試液体の飽和蒸気圧を実験変数とした噴孔内圧力の計測）査読

松本雅至, 井上欣也, 小橋好充, 松村恵理子, 千田二郎

日本機械学会論文集(B編) 78 ( 794 ) 1759 - 1768 2012年

Simultaneous reduction of pressure rise rate and emissions in a compression ignition engine by use of dual-component fuel spray

Yoshimitsu Kobashi, Hiroki Maekawa, Satoshi Kato, Jiro Senda

SAE Technical Papers 4 2012年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：SAE International

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Modeling of Auto-Ignition and combustion processes for dual-component fuel spray 査読

Yoshimitsu Kobashi, Kenta Fujimori, Hiroki Maekawa, Satoshi Kato, Daisuke Kawano, Jiro Senda

SAE International Journal of Engines 4 ( 2 ) 2193 - 2206 2011年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

Auto-ignition and combustion processes of dual-component fuel spray were numerically studied. A source code of SUPERTRAPP (developed by NIST), which is capable of predicting thermodynamic and transportation properties of pure fluids and fluid mixtures containing up to 20 components, was incorporated into KIVA3V to provide physical fuel properties and vapor-liquid equilibrium calculations. Low temperature oxidation reaction, which is of importance in ignition process of hydrocarbon fuels, as well as negative temperature coefficient behavior was taken into account using the multistep kinetics ignition prediction based on Shell model, while a global single-step mechanism was employed to account for high temperature oxidation reaction. Computational results with the present multi-component fuel model were validated by comparing with experimental data of spray combustion obtained in a constant volume vessel. The results showed a good agreement in terms of spray tip penetration, liquid length, ignition delay and so on, for several kinds of dual-component fuels. Additional investigation into a combustion control methodology using dual-component fuel, which aims to mitigate combustion rate of premixed charge, was performed. Consequently, the feasibility of this approach was confirmed. © 2011 SAE International.

DOI： 10.4271/2011-24-0001

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急速圧縮膨張装置を用いた二段噴射燃料の着火・燃焼過程に関する研究査読

小橋好充, 城戸良仁, 岸裏雅登, 千田二郎, 藤本元, 柴田元

自動車技術会論文集 42 ( 2 ) 477 - 482 2011年3月

Chemical kinetics study on ignition characteristics of biodiesel surrogates 査読

Kazunari Kuwahara, Koryu Nakahara, Yoshimitsu Wada, Jiro Senda, Yasuyuki Sakai, Hiromitsu Ando

SAE Technical Papers 780 - 797 2011年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Methyl butanoate (MB) and methyl decanoate (MD) are surrogates for biodiesel fuels. According to computational results with their detailed reaction mechanisms, MB and MD indicate shorter ignition delays than long alkanes such as n-heptane and n-dodecane do at an initial temperature over 1000 K. The high ignitability of these methyl esters was computationally analyzed by means of contribution matrices proposed by some of the authors. Due to the high acidity of an α-H atom in a carbonyl compound, hydroperoxy radicals are generated out of the equilibrium between forward and backward reactions of O2 addition to methyl ester radicals by the internal transfer of an α-H atom in the initial stage of an ignition process. Some of the hydroperoxy methyl ester radicals can generate OH to activate initial reactions. MB has an efficient CH3O formation path via CH3 generated by the β-scission of an MB radical which has a radical site on the α-C atom to the carbonyl group. MB has also other CH3O formation paths via some of fragmental oxygenated radicals. Therefore, the CH3O concentration is remarkably high in a thermal ignition preparation phase. The rich CH3O decomposes into CH2O and H, and then H combines with O2 into HO2. This exothermic reaction, H + O 2 + M = HO2 + M, plays a key role in promoting initial heat release. MD has efficient paths for initial heat release starting from the O2 addition to some of fragmental methyl ester radicals and ending in the OH formation via the internal transfer of an α-H atom. These paths considerably contribute not only to promoting initial heat release but also to generating OH in the initial stage of an ignition process. In conclusion, these mechanisms for the high ignitability are caused by a common local structure of methyl ester molecules, a carbonyl group in the molecule. © Copyright 2011 Society of Automotive Engineers of Japan, Inc. and SAE International.

DOI： 10.4271/2011-01-1926

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Effects of mixedness and ignition timings on PCCI combustion with a dual fuel operation 査読

Yoshimitsu Kobashi, Daijiro Tanaka, Teppei Maruko, Satoshi Kato, Masato Kishiura, Jiro Senda

SAE Technical Papers 699 - 713 2011年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

A dual fuel operation with different reactivity fuels has the possibility of optimizing performance and emissions in premixed charge compression ignition engines by controlling the spatial concentration and distribution of both fuels. In the present study, n-heptane and i-octane were independently injected through two different injectors. In-cylinder pressure analysis and emissions measurement were performed in a compression ignition engine. Injection timings, fuel quantity ratio between the injections were changed for the two cases, in which one fuel was injected using a port fuel injection system while the other was directly injected into the cylinder, in order to drastically vary mixture distributions and ignition timings. In addition, an optical diagnostic was performed in a rapid compression and expansion machine to develop an understanding of the ignition processes of the two mixtures. The experimental results show that not only the mixedness of the more reactive fuel n-heptane but also that of the less reactive fuel i-octane have significant impacts on the ignition timings, burn rates and emissions. As a first step to establish an optimum method of controlling burn rate, engine performance and emissions formation processes, the present study developed an understanding of the effects of the mixture distributions and ignition timings of two fuels on emissions and thermal efficiency. © Copyright 2011 Society of Automotive Engineers of Japan, Inc. and SAE International.

DOI： 10.4271/2011-01-1768

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Visualization of the cavitating flow inside the nozzle hole using by enlarged acrylic nozzle 査読

M. Matsumoto, Y. Inoue, E. Matsumura, Y. Kobashi, J. Senda

SAE Technical Papers 1644 - 1653 2011年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In this study, it is purpose to make clear the effect of cavitation phenomenon on the spray atomization. In this report, the cavitation phenomenon inside the nozzle hole was visualized and the pressure measurements along the wall of the nozzle hole were carried out by use of 25-times enlarged acrylic nozzle. For the representatives of regular gasoline, single and two-component fuels were used as a test fuel. In addition, various cavitating flow patterns same as experimental conditions were simulated by use of Barotropic model incorporated in commercial code of Star-CD scheme, and compared with experimental results. © Copyright 2011 Society of Automotive Engineers of Japan, Inc. and SAE International.

DOI： 10.4271/2011-01-2062

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直接サンプリングによるDIディーゼル機関の燃焼室内PMにDMC添加燃料が及ぼす影響解析査読

五十嵐智紀, 田浦寛斉, 小橋好充, 加藤聰

自動車技術会論文集 41 ( 6 ) 1335 - 1340 2010年11月

Spatial-Temporal Combustion Control in a CI Engine Based on Two-Stage Fuel Injection : Fundamental Study in a Rapid Compression and Expansion Machine 査読

KOBASHI, YOSHIMITSU, Yoshihito KIDO, Masato KISHIURA, Yoji Oyama, Masashi MATSUMOTO, Jiro SENDA, Hajime Gen, FUJIMOTO

THIESEL 2010 Conference on Thermo- and Fluid Dynamic Processes in Diesel Engines 235 - 251 2010年9月

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