研究者業績
基本情報
- 所属
- 千葉大学 大学院工学研究院 教授次世代モビリティパワーソース研究センター センター長
- 学位
- 工学博士工学修士
- J-GLOBAL ID
- 200901076796461220
- researchmap会員ID
- 1000010405
- 外部リンク
研究キーワード
8経歴
5-
2013年4月 - 現在
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2008年4月 - 現在
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1995年 - 2008年3月
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1994年 - 1995年
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1990年 - 1994年
学歴
4-
- 1990年
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- 1990年
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- 1985年
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- 1985年
委員歴
4-
2018年12月 - 2020年12月
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2015年1月
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2011年4月
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2008年4月
受賞
6-
2015年
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2011年12月
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2002年
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2001年
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1995年
論文
288-
Journal of Engineering for Gas Turbines and Power 146(10) 2024年8月21日 査読有りAbstract Although prechamber (PC) is regarded as a promising solution to enhance ignition in lean-burn gas engines, a lack of comprehensive understanding of PC jet penetration dynamics remains. This study proposed a zero-dimensional (0D) model for PC jet penetration, considering the mixing of combustion products and unburned gases in jets and the floating ejection pressure. A combustion completion degree was defined by employing fuel properties and heat release to estimate the time-varying jet density. Pressure differences between the PC and the main chamber (MC) were referred to as the ejection pressure. Then, this model was validated against experimental data from a constant volume chamber (CVC) and a rapid compression and expansion machine (RCEM) with CH4-H2 blends at different equivalent ratios. Results showed that the proposed model can provide a good prediction in stationary and turbulent fields with the calibrated model coefficient. The overall jet penetration exhibits a t0.5 dependence due to its single-phase characteristic and the relatively lower density compared to the ambient gas in MC. The flame propagation speed and heat release in PC influence the combustion completion degree at the start of jet ejection. The mass fraction of burned gas in the ejected jet grows in response to the mixture equivalent ratio. Jet penetration is primarily driven by ejection pressure, with tip dynamics barely affected by the pressure difference after peaks. Tip penetration intensity rises with increasing fuel equivalent ratio and H2 addition, owing to the faster flame propagation. These findings can offer useful suggestions for model-based design and combustion model development for gas engines.
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自動車技術会論文集 55(6) 1084-1090 2024年燃焼室を大小二つに分割することにより，予混合気圧縮着火燃焼を多段化することができる．本稿では冷却損失低減および高効率を狙い，小燃焼室をピストン内部に設けたときの本燃焼方式の実現可能性とポテンシャルを3D-CFDにより明らかにした．
MISC
255-
日本燃焼学会誌 = Journal of the Combustion Society of Japan 56(178) 298-307 2014年11月
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内燃機関シンポジウム講演論文集(CD-ROM) 25th 2014年
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内燃機関シンポジウム講演論文集(CD-ROM) 25th 2014年
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熱工学コンファレンス講演論文集 2014 _I211-1_-_I211-2_ 2014年Liquid fuel films attached on wall surfaces are presumed to cause soot emissions during the cold startup period of gasoline direct injection spark ignition engines. In this study, soot formation originated in combustion of liquid fuel films was investigated by using a 3D simulation. Calculations were performed for a Rapid Compression and Expansion Machine model. Effects of physical properties and the composition of the fuel were examined. Results showed that a portion of liquid fuel films remained until the end of the expansion stroke without evaporating even with the passage of the flame under the cold startup condition. Emission factors of liquid fuel films and soot were lager for PRF095 (i-C_8H_<18> 83%, n-C_7H_<16> 4%, C_6H_5CH_3 13%) than those of PRF100 (i-C_8H_<18> 100%). PRF100-ND having evaporation properties same as n-C_<10>H_<22> and chemical kinetics same as i-C_8H_<18> was prepared numerically. Emission factors of PRF100-ND were larger for liquid fuel films and smaller for soot than other fuels under the cold startup condition.
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プラズマ・核融合学会誌 = Journal of plasma and fusion research 89(4) 229-233 2013年4月25日現在,異分野融合型の新燃焼技術としてプラズマ支援燃焼が注目されている.これは,非熱平衡プラズマにより内燃機関の点火・燃焼を促進させようとするもので,自動車用ガソリンエンジン等への応用が期待されている.本章では,繰り返しナノパルス放電プラズマを用いた点火装置の開発を目的に,放電プラズマ中のラジカル(活性化学種)の基礎特性を調べた.また,小型の誘導エネルギー蓄積式パルス電源により生成される非平衡プラズマを用いた新たな点火装置を開発し,希薄燃焼時の点火特性の改善を図った.特に,定容燃焼器を用いて非平衡プラズマの点火機構の解明を試みると同時に,実エンジンへ適用した結果を述べる.
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微粒化 = Atomization : journal of the ILASS-Japan 22(75) 90-99 2013年3月31日
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動力・エネルギー技術の最前線講演論文集 : シンポジウム 2013 35-38 2013年Due to the environmental problems such as global warming and shortage of fossil fuel resources, natural gas and biomass ethanol have been used as alternative fuels of conventional gasoline Also high thermal efficiently combustion technology that can save fuel is strongly demanded Lean burn and EGR (Exhaust Gas Recirculation) dilution technology have been well known as high efficient combustion strategy However, dilution of mixture by air or EGR reduces ignitability and deteriorates ignition stability, Leading to slow burning velocity Recently, an ignition system which uses low-temperature plasma discharge has been proposed as a new device to improve ignition performance In this study, a performance of the newly developed repetitive pulse low temperature discharge ignition system was experimentally investigated The experiments were conducted using a small 4-stroke single cylinder engine Three fuels (gasoline, city gas, and ethanol) which have different ignitability were used As a result, the lean limit for stable ignition successfully was extended using the proposed low-temperature plasma discharge ignition system
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微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization 21 201-204 2012年12月17日
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日本機械学会関東支部総会講演会講演論文集 2012(18) 233-234 2012年3月8日The objective of this research is to investigate the effect of the EGR guide employed to generate a strong in-cylinder thermal stratification on the recharged EGR gas flow into the cylinder in a gasoline HCCI engine equipped with the blowdown supercharging (BDSC) system. The recharged EGR gas flow was visualized using an optical access engine by motoring. Gas flow from the exhaust port into the cylinder was visualized via PIV method. The results indicate that the flow field pattern is largely affected by the EGR guide's height, and that an increase in the EGR guide's height is effective to generate a strong in-cylinder thermal stratification.
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日本機械学会関東支部総会講演会講演論文集 2012 235-236 2012年The objective of this study is to establish a control strategy for a HCCI engine equipped with the blowdown supercharging system during the operating mode switching between HCCI and SI. 1-D numerical simulation model was developed to investigate transient behaviors of air-fuel mass ratio and gas-fuel mass ratio during the combustion mode transition. Using this code, an appropriate method to realize a smooth mode transition was explored. The simulation result indicates that a smooth operating mode transition would be possible with the optimized operating timings of the actuators such as intake throttle, exhaust throttle and fuel injector.
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日本機械学会関東支部総会講演会講演論文集 2012 245-246 2012年The purpose of traditional researches for knocking has been to suppress autoignition. However, the important problem is damages of engine components such as piston and valves by heavy pressure oscillation. Thereby, the aim of this study is to suppress the strong pressure oscillation, even if autoignition has occurred. The effect of spatial temperature distributions of mixture inside the cylinder on knocking intensity was examined using a rapid compression and expansion machine (RCEM). Result of this experiment shows a possibility that knocking intensity may be reduced by having a wide temperature difference of unburned mixture at the onset timing of autoignition.
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日本機械学会関東支部総会講演会講演論文集 2012 247-248 2012年In gasoline engines, port injected fuel impinges .on the wall of intake port and intake valves. Adhered fuel affects exhaust emissions. It is important to understand the liquid fuel thickness and its area formed by impinging on a wall for the decision of injector position and characteristics. In this paper, the liquid fuel thickness formed by impinging on a flat wall was measured using laser induced fluorescence method. The effect of properties of spray and the distance between the injector and the flat wall on the liquid fuel thickness and its area was investigated. The result shows that the liquid fuel is distributed in a ring shape at any distance and with any injector type. The less the hole of nozzle is, the less the fuel attachment takes.
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微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization 20 240-244 2011年12月16日
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年次大会 : Mechanical Engineering Congress, Japan 2011 "G070044-1"-"G070044-5" 2011年9月11日The objective of this research is to investigate the effect of the EGR guide employed to generate a strong in-cylinder thermal stratification on the recharged EGR gas flow into the cylinder in the gasoline HCCI engine equipped with the blowdown supercharging (BDSC) system. The recharged EGR gas flow was visualized using an optical access engine. A steady gas flow from the exhaust port into the cylinder was visualized via PIV method. The effect of the pressure difference between the exhaust port and the cylinder and the geometry of the EGR guide on the recharged gas flow were investigated. The results indicate that the flow field pattern is largely affected by the EGR guide height, and that an increase in the EGR guide height is effective to generate a strong in-cylinder thermal stratification.
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ETR : Engine technology review 2(2) 8-14 2010年6月
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Marine engineering : journal of the Japan Institution of Marine Engineering = マリンエンジニアリング : 日本マリンエンジニアリング学会誌 45(3) 408-414 2010年5月1日Diesel spray flame can be accurately predicted since Large Eddy Simulation (LES) can directly solve large-scale vortices. In this study, LES of the diesel spray flame in the combustion vessel is performed using KIVALES with a combustion model that applies CTC (Characteristic Time-scale Combustion) model to premixed combustion and FTS (Flamelet Time Scale) model to diffusion combustion. Damkohler number is used to determine premixed combustion or diffusion combustion. The effect of fuel droplet evaporation is considered in the transport equation of mixture fraction variance in order to improve the description of mixture fraction and its variance. Results show that the proposed combustion model can be applied accordingly to combustion configurations using the Damkohler number calculated using the turbulent characteristic time scale of the constant value.
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微粒化 = Atomization : journal of the ILASS-Japan 19(65) 25-31 2010年3月31日
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微粒化 = Atomization : journal of the ILASS-Japan 19(1) 25-31 2010年3月
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微粒化 = Atomization : journal of the ILASS-Japan 19(1) 25-31 2010年3月
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微粒化 = Atomization : journal of the ILASS-Japan 19(1) 25-31 2010年3月
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年次大会講演論文集 2010 95-96 2010年Large Eddy Simulation (LES) directly solves vortexes larger than a computational grid size. Therefore, LES is expected to make better predictions of unsteady turbulent reacting flow. This study was focused on refine predictions of diesel spray simulation, using KIVALES. Thus, we incorporated central difference method and forth-order Runge-Kutta method for the convection term of momentum equations and calculated evaporating diesel spray and diesel spray flame. The results showed that unsteady behavior in the near nozzle locations was predicted as compared with the conventional simulation results using CIP method. Additionally, good agreement of liquid and vapor penetration length and the heat release rate was obtained between the computational result and the experiments result.
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微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization 18 174-181 2009年12月16日
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微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization 18 227-232 2009年12月16日
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日本機械学会関東支部総会講演会講演論文集 2008 431-432 2008年Discrete droplet model (DDM) is widely used to calculate diesel sprays. In DDM, the spray tip penetration and the spray volume are often underpredicted. Therefore, various submodels such as breakup, drag force and collision models, are developed and improved. In this study, a newly developed drag force model, containing the drag reduction effect with the droplet spacing as a parameter is adopted and also, the effect on the spray tip penetration and the spray volume is examined. As a result, the drag reduction has much effect on the spray volume. The calculation results at the injection pressure of 133 and 55 MPa indicated good agreements with experiments.
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微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization 16 27-28 2007年12月19日
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微粒化 = Atomization : journal of the ILASS-Japan 15(52) 225-225 2007年1月31日
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微粒化シンポジウム講演論文集 = Symposium (ILASS-Japan) on Atomization 15 113-117 2006年12月18日
書籍等出版物
4Works(作品等)
9共同研究・競争的資金等の研究課題
15-
日本学術振興会 科学研究費助成事業 2015年4月 - 2018年3月
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日本学術振興会 科学研究費助成事業 基盤研究(C) 2015年4月 - 2018年3月
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日本学術振興会 科学研究費助成事業 2011年 - 2013年
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日本学術振興会 科学研究費助成事業 2008年 - 2010年
産業財産権
3-
US 6,581,553 B2
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特開2002-004865