LHD国际学术报告会

报告题目：二维直管道中暴燃到暴轰转变过程的数值模拟

报告人：窦华书教授 新加坡国立大学

报告时间：2010年7月21日(星期三)上午9:30

报告地点:力学所主楼312会议室

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Numerical Simulation of Deflagration to Detonation Transition in a Straight Duct

二维直管道中暴燃到暴轰转变过程的数值模拟

窦华书

Abstract In this study, numerical simulation based on Euler equation and on-step reaction model is carried out to investigate the process of deflagration to detonation transition (DDT) occurring in a straight duct. In particular, effects of activation temperature and channel blockage ratio on the DDT are studied. The model parameters used are the heat release at q=50, the specific heat ratio is 1.2, and the activation temperature at Ti=20, 15, and 10, respectively. It is found that the DDT occurrence strongly depends on the magnitude of the activation energy. The run-up distance of DDT increases with the value of activation energy. For activation temperature of Ti=20, the DDT process is not observed in the duct length simulated here. The reason for failure of DDT at large activation temperature is attributed to the decoupling of the shock wave and the flame front. With further downstream from the spark, this decoupling distance becomes increasingly larger. For the mid-value of activation temperature at Ti=15, the shock wave and the flame front are decoupled for a certain distance downstream from the spark. With further downstream, the DDT is generated owing to the self-ignition of the fuel heated by the passing shock wave or to the flame acceleration. At the low activation temperature of Ti=10, the shock wave and the flame front is tightly coupled. The collision of shock wave with the walls produces hot spots, which results in DDT occurrence. The detonation is generated within a short distance from the spark. The above found three types of DDT phenomena agree well, respectively, with those found in the experiments by Smirnov and Tyurnikov (1995). On the other hand, these results of simulation of DDT based on Euler equation share the main characteristic feature as those found from employing Navier-Stokes equations (SjOgreen and Tegner,2002). Therefore, it may be concluded that it is the interaction of shock wave and the flame front leading to the DDT occurrence. It is believed that these results may provide important information for further understanding of the DDT process and the related phenomena.

About the speaker

Dr. Hua-Shu Dou received a PhD degree in Aerodynamics from Beijing University of Aeronautics and Astronautics in 1991. Then, he joined Tsinghua University as a postdoctoral fellow and lecturer, and was subsequently promoted to associate professor in Tsinghua University in 1993. From 1994 to 1996, he worked in Tohoku University (Japan) as research fellow and Hosei University (Japan) as guest professor. From 1996 to 2002, he worked in The University of Sydney, Australia. Since 2002, he works in the National University of Singapore (NUS). Now, he is a Research Scientist in Temasek Laboratories at NUS and hold adjunction teaching position in mechanical engineering at NUS. Dr. Dou’s researches focus on computational fluid dynamics (CFD), aerodynamics, flow instability and turbulent transition, combustion and detonation, multiphase flows as well as numerical methods. He has published 90 papers in various refereed international journals and conferences. He has been invited to international conferences, universities, and companies to give lectures. He was in the committees of several international conferences and served as Session Chairman for several international conferences. He is currently in the Editorial Boards of 4 international journals. He is a member of ASME and APS as well as a senior member of AIAA.