研究者詳細 - 小橋　好充

論文 - 小橋　好充

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Combustion Noise Reduction with High Thermal Efficiency by the Control of Multiple Fuel Injections in Premixed Diesel Engines 査読

Gen Shibata, Hideyuki Ogawa, Yuki Okamoto, Yasumasa Amanuma, Yoshimitsu Kobashi

SAE International Journal of Engines 10 ( 3 ) 1128 - 1142 2017年3月

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

Premixed diesel combustion is effective for high thermal efficiency and reductions of NOx and PM emissions, but a reduction of combustion noise is necessary for medium-high load engine operation. The control of the fuel injection has become more accurate because of the technical progress of the common rail fuel injection system, and the target heat release shape, calculated by computation, can be achieved by control of EGR, boosting, fuel injection timing, and injection quantity of multiple fuel injections. In this paper, the reduction of premixed diesel combustion noise maintaining high thermal efficiency has been investigated by the control of injection timings and heating values of multiple fuel injections. There are two aspects of the combustion noise reduction by multiple fuel injections. One is the reduction of the maximum rate of pressure rise in each combustion cycle, and the other is noise reduction effects by the noise cancelling spike (NCS) combustion. The research was conducted with both engine simulations and experiments. In combustion noise simulations, the heat release history of multiple injections was approximated by Wiebe functions and the simulated combustion noise was calculated from the fitted curve of the heat release and the coherence transfer function. The structural attenuation (SA) of the test engine was calculated from the power spectrum of the FFT analysis of the in-cylinder pressure wave data and the cross power spectrum of the sound pressure of the engine noise by the coherence method, then the combustion noise (CNL) can be calculated from the structural attenuation and cylinder pressure level (CPL) in the simulation, as shown in equation 4. The simulation results were confirmed by the engine tests. First, the combustion noise reduction by two stage fuel injection was investigated. The maximum rate of pressure rise changes depending on the combustion occurring separately in the compression and expansion strokes. One heat release was set at TDC and the second before or after the TDC. In the late two stage combustion as shown in Figure 12 (b), the combustion noise reduction was most effectively achieved when the heating value of Q2nd is higher than that of Q1st, however in the early two stage combustion in Figure 12 (a), the Q1st heat release occurs during the compression stroke and the combustion noise reduction by the early two stage NCS combustion is more effective than the combustion noise reduction by the late two stage NCS combustion. Three stage combustion simulations were also investigated at 0.6MPa IMEP and 2000 rpm. The optimum heat release shape for low combustion noise and high indicated thermal efficiency was calculated and the role of each part of the heat release in the three stage combustion is discussed. The simulation predicted 87.1 dBA of combustion noise and 50.3 % of indicated thermal efficiency. Finally, the effects of multiple fuel injections on the degree of constant volume and combustion noise are analyzed and discussed.

DOI： 10.4271/2017-01-0706

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ゼオライト触媒を用いたNH3-SCR 反応モデルの開発査読

永島渉, 小祝隆太郎, 柴田元, 小川英之, 小橋好充, 草鹿仁, 植西徹

自動車技術会論文集 48 ( 2 ) 299 - 304 2017年3月

詳細反応機構の解読にもとづくノルマルトリデカンの簡略化反応機構の構築査読

桑原一成, 松尾直, 酒井康行, 小橋好充, 堀司, 松村恵理子, 千田二郎

自動車技術会論文集 48 ( 1 ) 27 - 33 2017年1月

An Investigation of the Transient DPF Pressure Drop under Cold Start Conditions in Diesel Engines 査読

Yoshimitsu Kobashi, Shun Oooka, Lin Jiang, Jun Goto, Hideyuki Ogawa, Gen Shibata

SAE Technical Papers 2017- 2017年

担当区分：筆頭著者記述言語：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

To monitor emission-related components/systems and to evaluate the presence of malfunctioning or failures that can affect emissions, current diesel engine regulations require the use of on-board diagnostics (OBD). For diesel particulate filters (DPF), the pressure drop across the DPF is monitored by the OBD as the pressure drop is approximately linear related to the soot mass deposited in a filter. However, sudden acceleration may cause a sudden decrease in DPF pressure drop under cold start conditions. This appears to be caused by water that has condensed in the exhaust pipe, but no detailed mechanism for this decrease has been established. The present study developed an experimental apparatus that reproduces rapid increases of the exhaust gas flow under cold start conditions and enables independent control of the amount of water as well as the gas flow rate supplied to the DPF. The results show that the sudden decrease in the DPF pressure drop is caused by the water in the developed system used here. Observations of the soot cake layers in the DPF show that the decrease in the DPF pressure drop is caused by peeling-off and separation of the soot cake layer from the walls of the DPF. An increase in the water flow rate thins the soot cake layer and decreases the DPF pressure drop. Further, numerical simulation using a DPF model developed by a research group at Waseda University was also performed, and the calculated DPF pressure drop captures the changes obtained by the experiments well.

DOI： 10.4271/2017-01-2372

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ディーゼル噴霧火炎における壁面熱損失に関する研究 —噴射圧力が熱流束に及ぼす影響— 査読

巽健, 前田篤志, 宮田哲次, 小橋好充, 桑原一成, 松村恵理子, 千田二郎

自動車技術会論文集 47 ( 6 ) 1291 - 1296 2016年

Reduction of Reaction Mechanism for n -Tridecane Based on Knowledge of Detailed Reaction Paths 査読

Kazunari Kuwahara, Tadashi Matsuo, Yasuyuki Sakai, Yoshimitsu Kobashi, Tsukasa Hori, Eriko Matsumura, Jiro Senda

SAE Technical Papers 2016- 2016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

n-Tridecane is a low boiling point component of gas oil, and has been used as a single-component fuel for diesel spray and combustion experiments. However, no reduced chemical kinetic mechanisms for n-tridecane have been presented for three-dimensional modeling. A detailed mechanism developed by KUCRS (Knowledge-basing Utilities for Complex Reaction Systems), contains 1493 chemical species and 3641 reactions. Reaction paths during ignition process for n-tridecane in air computed using the detailed mechanism, were analyzed with the equivalence ratio of 0.75 and the initial temperatures of 650 K, 850 K, and 1100 K, which are located in the cool-flame dominant, negative-temperature coefficient, and blue-flame dominant regions, respectively. Based on knowledge derived from the reaction path analysis, a skeletal mechanism containing 49 species and 85 reactions, was developed and validated for representing ignition characteristics over a wide range of initial conditions computed using the detailed mechanism. The skeletal mechanism includes C3H7, C2H5, and CH3 as representative fragmental alkyl radicals, C7H14, C3H6, and C2H4 as representative alkenes, and C3H7CHO and CH2O as representative aldehydes. C3-series reactions beginning with O2 addition to C3H7, were expressed using parameters for C6-series reactions, which took similar reactions for larger alkyl radicals into consideration. Ignition delay times and low-temperature oxidation induction times with the initial temperatures between 600 K and 1200 K using the skeletal mechanism, and their dependences on pressure and equivalence ratio in lean and stoichiometric cases agree well with those using the detailed mechanism. However, the agreement becomes worse as equivalence ratio is increased in rich cases.

DOI： 10.4271/2016-01-2238

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ガソリン系燃料のオクタン価が二燃料成層自着火の着火と燃焼過程に及ぼす影響査読

武藤涼, 髙木圭一朗, 横川和弘, 小橋好充, 加藤聰

自動車技術会論文集 47 ( 2 ) 299 - 305 2016年

化学反応速度論にもとづくオクタン価リファレンス燃料の着火遅れ式（第２報） −低温酸化反応を経由する低温条件の着火過程− 査読

中谷匡希, 桑原一成, 多田卓矢, 古谷正広, 小橋好充, 酒井康行, 松村恵理子, 千田二郎

自動車技術会論文集 47 ( 1 ) 9 - 15 2016年

ガソリン圧縮着火燃焼における二段噴射の役割査読

小橋好充, 松本彬良, 武藤涼, 加藤聰, 藤野友基, 川北晋一郎, 近藤和吉, 西島義明

自動車技術会論文集 47 ( 1 ) 87 - 92 2016年

Premixed Fuel Effect on Ignition and Combustion of Dual Fuel Compression Ignition Engine 査読

Yoshimitsu Kobashi, Ryo Muto, Satoshi Kato

SAE Technical Papers 2015- ( September ) 2015年9月

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

Effects of chemical reaction characteristics of premixed fuel were experimentally studied in a dual fuel compression ignition engine using port injection (PI) of gasoline-like component and direct injection (DI) of diesel fuel. Octane number of port injection fuels, direct injection timing and injection amount ratio between PI and DI were swept to assess the interaction between chemical reaction and mixture distribution in a combustion chamber. Chemical kinetic study using multi-zone modeling was also performed in order to explain experimental results under quiescent condition.

DOI： 10.4271/2015-01-1789

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Artificial Control of Diesel Spray and Flame Feature by using Dual-component Fuel 査読

Satoshi Miyata, Yu Kuwahara, Yoshimitsu Kobashi, Kazunari Kuwahara, Eriko Matsumura, Jiro Senda

SAE Technical Papers 2015- ( September ) 2015年9月

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

Fuel design approach has been proposed as the control technique of spray and combustion processes in diesel engine to improve thermal efficiency and reduce exhaust emissions. In order to kwow if this approach is capable of controlling spray flame structure and interaction between the flame and a combustion chamber wall, the present study investigated ignition and flame characteristics of dual-component fuels, while varying mixing fraction, fuel temperature and ambient conditions. Those characteristics were evaluated through chemiluminescence photography and luminous flame photography. OH radical images and visible luminous flame images were analyzed to reveal flame shape aspect ratio and its fractal dimension.

DOI： 10.4271/2015-01-1916

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種々の二成分混合燃料を用いたディーゼル燃焼における着火および火炎構造に関する研究査読

千田二郎, 味岡将士, 向山智之, 宮田哲次, 桑原悠, 小橋好充, 桑原一成, 松村恵理子

自動車技術会論文集 46 ( 2 ) 349 - 354 2015年3月

ジャトロファ油／灯油混合燃料を用いたコモンレール式ディーゼル機関の特性査読

朝香勝義, 横川和弘, 小橋好充, 加藤聰, 鈴木康允, Alberto MACAMO

日本機械学会論文集 81 ( 824 ) 2015年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：The Japan Society of Mechanical Engineers

Oil derived from Jatropha is a potential alternative to fossil fuels for Diesel engines in Mozambique because it can be cheaper and more easily available than fatty acid methyl ester, though the physical properties, e.g. high viscosity, might be a problem. As an attempt to use Jatropha oil (JO) in Diesel engines, the present study mixed JO into kerosene. Engine tests as well as un-evaporating spray visualization were carried out. The results demonstrated that a single cylinder engine can be successfully operated with JO blended kerosene despite the fact that the ignition delay is slightly longer than diesel fuel. There were no significant changes of exhaust gas emissions. It is also clear that mixing JO into kerosene can contribute to the reductions of insoluble fraction and soluble organic fraction contained in particulate matter than mixing into diesel fuel.

DOI： 10.1299/transjsme.14-00527

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A Comparative Analysis of Combustion Process, Performance and Exhaust Emissions in Diesel Engine Fueled with Blends of Jatropha Oil-Diesel Fuel and Jatropha Oil-Kerosene 査読

Takaaki Yamaji, Katsuyoshi Asaka, Yoshimitsu Kobashi, Satoshi Kato, Yasumitsu Suzuki, Albert Macamo

SAE Technical Paper 2015-32-0797 2015年

Analysis of Turbulence in Diesel Spray Using Time-Resolved PIV 査読

Kazuyoshi.Yokogawa, Yoshimitsu.Kobashi, Satoshi.Kato

13th Triennial International Conference on Liquid Atomization and Spray Systems 2015年

化学反応速度論にもとづくオクタン価リファレンス燃料の着火遅れ式 −低温酸化反応を経由しない高温条件の着火過程− 査読

桑原一成, 多田卓矢, 古谷正広, 大嶋元啓, 小橋好充, 酒井康行, 安東弘光, 松村恵理子, 千田二郎

自動車技術会論文集 46 ( 5 ) 851 - 857 2015年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人自動車技術会

KUCRS が提供する詳細反応モデルを用いてノルマルヘプタンとイソオクタンのそれぞれについて着火遅れ式を導出する．この着火遅れ式は，着火遅れ時間の燃料濃度依存性，酸素濃度依存性，第三体濃度依存性，熱容量依存性などを分離して記述し，シリンダー内のあらゆる着火現象に適用することを想定したものである．

DOI： 10.11351/jsaeronbun.46.851

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Exhaust Emission Characteristics of Diesel Engine Using Jatropha Crude Oil Blends 査読

Satoshi Kato, Yoshimitsu Kobashi, Yasumitsu Suzuki, Koji Tosa, Katsuyoshi Asaka, Alberto Macamo

SAE Technical Papers 2014- 2014年10月

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

Jatropha biofuel is promising renewal oil to produce biodiesel fuel through transesterification method which is shown in many papers. The ideal diesel alternative fuel obtained considering Jatropha as materials is Fatty Acid Methyl Ester (FAME). It is more desirable than the viewpoint of economical efficiency and CO&lt
inf&gt
2&lt
/inf&gt
control to operate a diesel engine with Jatropha crude (JC) oil. It is the purpose of this research to examine a possibility of using advantageous JC oil direct use as diesel engine fuel, in consideration of the sustainable production of the Jatropha biofuel in Mozambique. The adaptability to the diesel engine of diesel oil and the mixed fuel of JC was examined. Jatropha crude oil contains phorbol ester (PEs) which is a promoter of cancer. Measurement of the concentration of PEs in an exhaust gas was performed using High Performance Liquid Chromatography (HPLC). Skip cycle operation was performed for diesel engine with an electronically-controlled fuel injection system, and it was checked that the PEs concentration in the exhaust gas in low load operation which imitated cold starting condition. As a result of conducting the experiment by the JC mixed fuel up to JC60 had little influence on indicated thermal efficiency and the exhaust gas components except PM, and it has checked the possibility of utilization. However, PM in an exhaust gas increased in proportion to the mixed ratio of JC. Also in the skip cycle which imitated cold starting, it checked that the PEs concentration in an exhaust gas was below a detection limit.

DOI： 10.4271/2014-01-2770

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Experimental Validation of a Droplet Vaporization Model for Ethanol-Blended Fuels and its Application to Spray Simulation 査読

Yoshimitsu Kobashi, Yusuke Kimoto, Satoshi Kato

SAE Technical Papers 2014- 2014年10月

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

Ethanol is a promising alternative to fossil fuels because it can be made from biomass resources that are renewable. In the most cases, however, ethanol is blended with conventional fuels because of the limited amount of production. Ethanol-fuel blends are typically azeotropic and have a unique characteristic in vapor pressure and phase equilibrium, which is different from that of blends composed of simple aliphatic hydrocarbons. The current studies by the authors have developed a numerical vaporization model for ethanol-gasoline blends, which takes into account vapor-liquid equilibrium of azeotrope and high latent heat of vaporization of ethanol, in order to update the authors' multicomponent fuel spray model and to investigate effects of blending ethanol on droplet vaporization processes. In this paper, the developed vaporization model was validated through a comparison with experimentally-observed vaporization rate for single droplets of ethanol-n-heptane blends. The predicted results were in a good agreement with experimental data. The results also showed that the latent heat of vaporization of ethanol plays an important role in a droplet vaporization rate while the increase of the vapor pressure due to mixing ethanol has less effect and that consideration of the phase equilibrium composition is required to correctly predict the temporal change of the composition in a vaporizing droplet. Finally, the developed vaporization model was incorporated into authors' multicomponent fuel spray model. The effects of liquid-vapor equilibrium of ethanol-n-heptane blends and the latent heat of vaporization of ethanol were evaluated for vaporizing fuel spray.

DOI： 10.4271/2014-01-2733

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ジャトロファ油混合燃料を用いたディーゼル機関の特性と排気微粒子中のホルボールエステル査読

小橋好充, 朝香勝義, 加藤佳也, 加藤聰, 土佐光司, 鈴木康允

自動車技術会論文集 45 ( 2 ) 185 - 190 2014年3月

エタノール-ノルマルヘプタン混合燃料の液滴蒸発モデルの評価と蒸発噴霧への適用査読

木本裕輔, 小橋好充, 加藤聰

自動車技術会論文集 45 ( 5 ) 817 - 822 2014年

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