| Project/Area Number |
09650220
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Tohoku University |
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Principal Investigator |
JU Yiguang Tohoku Univ., Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (60261468)
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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 |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Detonation / Supersonic projectile / Non-uniform mixture / High pressure / Detonation limit / Initiation condition / Critical scale / 開始 / 限界スケール / 部分子混合 / 反応機構 |
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| Research Abstract |
1. Detonation initiation by a supersonic sphere was examined numerically and theoretically. A theoretical expression for the detonation initiation boundary was obtained. It was shown That detonation initiation is determined by two limits, the energy limit and the kinetic limit. The comparison with the experimental data shows that the diaphragm has a large effect on the experimental data. Accurate determination of detonation initiation requires to remove the diaphragm effect. It was shown that the present prediction agree swell with the improved experimental data.
2.The dependence of kinetic limit on the pressure was investigated. Base on the newest experimental data of reaction HO2+HO2=H2O4, an approximated expression for this reaction rate was derived and fitted. A new chemical kinetic mechanism for H2/O2 mixture at high pressure was compiled and verified. The ignition time at a wide range of pressures was calculated and compared with experiment.
3.The detonation initiation condition wa
… More
s calculated using the newly-developed chemical mechanism. It was shown that the chemical kinetics has a considerable effect on the detonation initiation boundary.
4. Detonation initiation in a non-uniform mixture by a supersonic sphere is investigated numerically with detailed chemical kinetics. Particular attention is paid to the effects of the non-uniform mixture scale on the detonation initiation and propagation under various pressures. The results showed that the decrease of the scale of the non-uniform mixture results in a decrease of the detonation velocity, It is found that detonation propagation is quenched as the scale of the non-uniform mixture reaches a critical value. The results are compared with the cell-size based experimental data and the theoretical prediction. Two mechanisms for the existence of this critical scale are presented and discussed.
5. Transition process near the detonation limit was examined. It was found that there is a transition instability near the detonation boundary. The over-driven detonation propagates forward with a regular step-jump of the detonation front. Further studies on this instability is necessary in the future. Less
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