| Project/Area Number |
09450092
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
IKEGAMI Makoto KYOTO UNIVERSITY,Faculty of Energy Science, Professor, エネルギー科学研究科, 教授 (70025914)
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| Co-Investigator(Kenkyū-buntansha) |
KAWANABE Hiroshi KYOTO UNIVERSITY,Faculty of Energy Science, Instractor, エネルギー科学研究科, 助手 (60273471)
ISHIYAMA Takuji KYOTO UNIVERSITY,Faculty of Energy Science, Associate Professor, エネルギー科学研究科, 助教授 (30203037)
SIOJI Masahiro KYOTO UNIVERSITY,Faculty of Energy Science, Professor, エネルギー科学研究科, 教授 (80135524)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥14,000,000 (Direct Cost: ¥14,000,000)
Fiscal Year 1998: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1997: ¥10,600,000 (Direct Cost: ¥10,600,000)
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| Keywords | Diesel Combustion / Ignition Process / Turbulent Mixing / Ignition Delay / Initial Combustion / Stochastic Model / Injection Rate / 濃度不均一 / 2体衝突再分散モデル |
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| Research Abstract |
To describe the ignition delay of diesel sprays, a stochastic model taking account of the endothermic process in the spray is proposed. In this model, generation of turbulence and turbulent mixing of fuel and air are taken into consideration. For the endothermic process, the rate of heat absorption due to vaporization and pyrolysis is assumed to be constant. Chemical reactions during the ignition delay period are expressed by a one-step global mechanism and ignition is assumed to occur when concentrations of active species exceed a threshold. It is shown that this model may reproduce the ignition delay of a diesel spray and pressure history in a rapid compression machine for a variety of conditions. Also, the ignition delay is dependent on spray formation at a high initial temperature, but on chemical reaction at a low initial temperature.
Furthermore, this approach is applied to predict the initial combustion in diesel engines for various injection rates including pilot injection. In this model, heterogeneity of fuel concentration and temperature is expressed by probability density functions Due to the heat and mass exchange associated with the collision, the initial segregation tends to form a mixture of less heterogeneity as time goes on. Maximum rates of heat release correspond to the predicted results by varying delay mechanism. It is also shown that when injection pressure is high and nozzle diameter is small, pilot injection efficiently gives a smooth burning. When an appropriate constant of heat absorption is given as a function of injection pressure, nozzle diameter, ambient temperature and pressure, ignition delay periods are successfully predicted for a wide range of injection conditions. Based on the predicted results, a discussion is made about the effect of high-pressure injection on the ignition process.
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