研究者詳細 - 小橋　好充

論文 - 小橋　好充

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ディーゼル燃焼のサイズ依存性を考慮した燃焼改善法の検討招待査読

小橋好充, 新山紘史, 柴田元, 小川英之

マリンエンジニアリング 56 ( 4 ) 592 - 599 2021年7月

Mechanism of thermal efficiency improvement in twin shaped semi-premixed diesel combustion 査読

Kazuki Inaba, Yanhe Zhang, Yoshimitsu Kobashi, Gen Shibata, Hideyuki Ogawa

International Journal of Engine Research 146808742110264 - 146808742110264 2021年6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：SAGE Publications

Improvements of the thermal efficiency in twin shaped semi-premixed diesel combustion mode with premixed combustion in the primary stage and spray diffusive combustion in the secondary stage with multi-stage fuel injection were investigated with experiments and 3D-CFD analysis. For a better understanding of the advantages of this combustion mode, the results were compared with conventional diesel combustion modes, mainly consisting of diffusive combustion. The semi-premixed mode has a higher thermal efficiency than the conventional mode at both the low and medium load conditions examined here. The heat release in the semi-premixed mode is more concentrated at the top dead center, resulting in a significant reduction in the exhaust loss. The increase in the cooling loss is suppressed to a level similar to the conventional mode. In the conventional mode the rate of heat release becomes more rapid and the combustion noise increases with advances in the combustion phase as the premixed combustion with pilot and pre injections and the diffusive combustion with the main combustion occurs simultaneously. In the semi-premixed mode, the premixed combustion with pilot and primary injections and the diffusive combustion with the secondary injection occurs separately in different phases, maintaining a gentler heat release with advances in the combustion phase. The mechanism of the cooling loss suppression with the semi-premixed mode at low load was investigated with 3D-CFD. In the semi-premixed mode, there is a reduction in the gas flow and quantity of the combustion gas near the piston wall due to the suppression of spray penetration and splitting of the injection, resulting in a smaller heat flux.

DOI： 10.1177/14680874211026429

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その他リンク： http://journals.sagepub.com/doi/full-xml/10.1177/14680874211026429

Optimization of Gasoline Compression Ignition Combustion with Ozone Addition and Two-stage Direct-injection at Middle Loads 査読

Yoshimitsu Kobashi, Tu Dan Dan Da, Ryuya Inagaki, Gen Shibata, Hideyuki Ogawa

International Journal of Engine Research 1 - 11 2021年1月

EGR gas composition effects on ignition delays in diesel combustion 査読

Yoshimitsu Kobashi, Masaki Todokoro, Gen Shibata, Hideyuki Ogawa, Toshihiro Mori, Daichi Imai

Fuel 281 118730 - 118730 2020年12月

Mechanism of Thermal Efficiency Improvement in Twin Shaped Semi-Premixed Diesel Combustion 査読

Kazuki Inaba, Yanhe Zhang, Yoshimitsu Kobashi, Gen Shibata, Hideyuki Ogawa

THIESEL 2020 Conference on Thermo- and Fluid Dynamic Processes in Direct Injection Engines 220 - 232 2020年9月

Kinetic Modeling of Steady-state NH3-SCR over a Monolithic Cu-CHA 査読

Wataru Eijima,, Gen Shibata, Naoki Shibayama, Yoshimitsu Kobashi, Hideyuki Ogawa, Ken-ichi Shimizu

Catalysis Today 352 237 - 242 2020年8月

Fuel adhesion and oil splash on oil-wet cylinder walls with post diesel fuel injections 査読

Gen Shibata, Shogo Nishiuchi, Shuntaro Takai, Yoshimitsu Kobashi, Hiroki Kanbe, Eriko Matsumura

International Journal of Engine Research 146808742091414 - 146808742091414 2020年5月

Optimization of combustion noise and thermal efficiency in diesel engines over a wide speed and load operational range 査読

Gen Shibata, Kohei Yamamoto, Mikito Saito, Yuto Inoue, Yasumasa Amanuma, Yoshimitsu Kobashi

International Journal of Engine Research 21 ( 4 ) 698 - 712 2020年4月

掲載種別：研究論文（学術雑誌）出版者・発行元：SAGE Publications

Pre-mixed diesel combustion has the potential of offering high thermal efficiency with low emissions; however, this may result in loud combustion noise because of the high maximum rate of pressure rise. Combustion noise and thermal efficiency work in a trade-off relation, and it has not been possible to achieve high thermal efficiency with low combustion noise, so far. Our laboratory has worked on combustion noise simulations calculated from the heat release history, and it is now possible to calculate a heat release shape for high thermal efficiency with low combustion noise. In this article, the objective of the research is the reduction of combustion noise by multiple fuel injections with high indicated thermal efficiency for a wide range of engine speeds and loads. The engine employed in the simulations and experiments is a supercharged, single-cylinder direct-injection diesel engine, with a high-pressure common rail fuel injection system. The heat release is approximated by Wiebe functions, and the combustion noise and indicated thermal efficiency are calculated in simulations. The engine operational range was divided into 12 conditions, four engine speed conditions each at three engine load conditions, and the optimum heat release shape for low combustion noise with high indicated thermal efficiency was calculated by a genetic-based algorithm method. The parameters for the genetic-based algorithm simulation were the number of injections, each injection timing, the heating value in each heat release, and the combustion period of each injection. The optimum heat release shape is a delta triangle (Δ)-shaped heat release (the heat release increase in the expansion stroke) with a high degree of constant volume for all conditions; however, the optimum number of heat releases and the injection timing are different depending on the engine speed and load conditions. The simulated results were confirmed by engine tests.

DOI： 10.1177/1468087419866069

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その他リンク： http://journals.sagepub.com/doi/full-xml/10.1177/1468087419866069

Effect of Storage Conditions on the Quality of Jatropha curcas Oils 査読

Alberto Julião Macamo, Carlos Lucas, Katia Marcos Boene, Lucrécio Biquiza, Yoshimitsu Kobashi, Satoshi Kato

Energy&Fuels 1 - 5 2020年3月

Measurements of fuel adhesion on cylinder walls and fuel wall-flow behavior with post diesel fuel injections 査読

Gen Shibata, Shogo Nishiuchi, Puqing Xie, Shuntaro Takai, Hideyuki Ogawa, Yoshimitsu Kobashi

International Journal of Engine Research 21 ( 2 ) 352 - 366 2020年2月

掲載種別：研究論文（学術雑誌）出版者・発行元：SAGE Publications

Post fuel injection in the expansion stroke is used for diesel particulate filter regeneration; however, fuel spray impinges on the cylinder liner due to the low temperature and pressure conditions. Fuel adhesion and fuel flowing down across the cylinder liner, the so-called “wall-flow,” was observed by high-speed video images, and this adhesion is a cause of diesel engine lubricant oil dilution and the deterioration of fuel consumption in diesel engines. In this article, the fuel adhesion and the wall-flow of post diesel fuel injections were investigated with a high pressure-temperature constant volume optical chamber. The in-cylinder temperatures and pressures at 30, 60, and 90 °CA ATDCs, conditions commonly employed in post fuel injection timings, were measured by an actual engine, and similar conditions were created in the constant volume chamber by the combustion of a pre-mixed gas of ethylene, oxygen, and nitrogen. Fuel masses of 0.6, 1.1, and 1.7 mg per hole were injected at each ATDC setting. The weight of the adhered fuel on the wall and the fuel in the piston-cylinder crevice were measured by precision balance, and the liquid–vapor phases in the spray were observed by Mie scattering and shadowgraph methods. To measure the thickness of the adhered fuel on the cylinder wall, the laser-induced fluorescence method was employed. The results show that the fuel spray penetration and adhesion on the cylinder wall were different in the test conditions investigated here. With the early post injection, most of the injected fuel vaporizes without penetrating to the cylinder liner and gaseous diesel fuel is condensed on the cylinder wall. A thin and widely spread out fuel film is formed on the cylinder wall; however, no wall-flow could be confirmed by the high-speed video images. With late post fuel injections, the strong penetration of liquid fuel reaches the cylinder wall, and a thick and widely spread out fuel film was formed on the cylinder wall and the wall-flow phenomenon was observed here. However, the quantity of fuel involved in the wall-flow was smaller than that of the fuel adhering to the cylinder wall. The effects of in-cylinder pressure and temperature on the fuel adhesion on the cylinder wall were investigated. With the increase in pressure and temperature, the quantity of adhering fuel was reduced, suggesting that the boost pressure increase by turbo charging and a higher engine load is effective to reduce fuel adhesion. Furthermore, the effects of multiple post fuel injections on fuel adhesion to the cylinder wall were investigated, maintaining the total fuel injection amounts. With increases in the number of fuel injections, the total percentage of adhering post fuel on the cylinder wall was reduced. In the multiple fuel injections, it was observed that fuel motion takes place during the spray pass after the first and second fuel injections and that the penetration length of the second and third fuel sprays increases.

DOI： 10.1177/1468087419855200

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その他リンク： http://journals.sagepub.com/doi/full-xml/10.1177/1468087419855200

Modeling wall film formation and vaporization of a gasoline surrogate fuel 査読

Yoshimitsu Kobashi, Yoshio Zama, Tatsuya Kuboyama

International Journal of Heat and Mass Transfer 147 2019年11月

反射衝撃波背後における3成分ガソリンサロゲート燃料の煤生成特性査読

田中万里子, 永田勇気, 石井一洋, 小橋好充

自動車技術会論文集 50 ( 5 ) 1224 - 1229 2019年9月

An Investigation of the Effects of Engine Size and Rotation Speed on Diesel Combustion based on Similarity Rules 査読

Yoshimitsu Kobashi, Yuma Tanaka, Gen Shibata, Hideyuki Ogawa

SAE Technical Paper 2019-01-2181 2019年8月

A Study of a Lean Homogeneous Combustion Engine System with a Fuel Reformer Cylinder 査読

Go Asai, Yuki Tokuoka, Thomas Bayer, Shuntaro Ishiguro, Gen Shibata, Hideyuki Ogawa, Yoshimitsu Kobashi, Yusuke Watanabe

SAE Technical Paper 2019-01-2177 2019年8月

Study for Ignition Characteristics and Potential of Gasoline Autoignition Combustion with Spark Assist 査読

Kaname Naganuma, Koki Tanaka, Tsubasa Ito, Yoshimitsu Kobashi

SAE Technical Paper 2019-01-2317 2019年8月

Thermal Efficiency Improvements with Split Primary Fuel Injections in Semi-Premixed Diesel Combustion with Multi-Peak Shaped Heat Release 査読

Kazuki Inaba, Yosuke Masuko, Yanhe Zhang, Yoshimitsu Kobashi, Gen Shibata, Hideyuki Ogawa

SAE Technical Paper 2019-01-2170 2019年8月

Ignition Control in a Gasoline Compression Ignition Engine with Ozone Addition Combined with a Two-Stage Direct-Injection Strategy 査読

Y. Kobashi, Y. Wang, G. Shibata, H. Ogawa, K. Naganuma

Fuel 249 154 - 160 2019年8月

気筒内燃料改質ガスを用いたディーゼル混焼機関の研究（第２報）査読

朝井豪, 石黒俊太郎, 三本連太郎, 渡辺勇介, 柴田元, 小川英之, 小橋好充

自動車技術会論文集 20194559 Vol. 50 ( No. 4 ) 1030 - 1035 2019年7月

気筒内燃料改質ガスを用いたディーゼル混焼機関の研究（第１報）査読

石黒俊太郎, 朝井豪, 渡辺勇介, 柴田元, 小川英之, 小橋好充

自動車技術会論文集 20194558 Vol. 50 ( No.4 ) 1024 - 1029 2019年7月

Thermal Efficiency Improvement and its Mechanism at Low Load Conditions in Semi-Premixed Diesel Combustion with Twin Peak Shaped Heat Release 査読

Kazuki Inaba, Yosuke Masuko, Yanhe Zhang, Yoshimitsu Kobashi, Gen Shibata, Hideyuki Ogawa

SAE Technical Paper 2019-01-1153 2019年4月

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