气相爆轰波正反射激波加速研究

Study on acceleration of shock generated by normal reflection of gaseous detonation wave

实验采用压力传感器测量了指定点压力时间曲线。数值模拟基于二维反应欧拉方程和基元反应模型,采用二阶附加半隐的龙格-库塔法和5阶WENO格式分别离散时间和空间导数项,获得了指定点数值压力时间曲线。理论分析基于爆轰理论和激波动力学,分析了气相爆轰波反射过程所涉及的复杂波系演变并获得了反射激波速度。结果表明:本文数值模拟和理论计算定性上重复并解释了实验现象。气相爆轰波在右壁面反射后,右行稀疏波加速反射激波。其加速原因是:尽管激波波前声速减小,但激波马赫数增大,波前气流速度减小。在低初压下,可能还由于爆轰波后未反应或部分反应气体的作用,导致反射激波加速幅度比高初压下大。

Acceleration of the shock generated by normal reflection of gaseous detonation wave was experimentally, numerically and theoretically investigated. The pizeo-electric transducers were employed to obtain the pressure history at the specific port. Based on two-dimensional reactive Euler equations and detailed chemical reaction model, numerical simulation was performed. The 2nd additive semi-implicit Runge-Kutta method and 5th order WENO scheme were respectively used to discretize the time and space terms. The numerical pressure history at the specific port was also obtained. Based on detonation theory and shock dynamics, the complicated wave evolution involved in the process of gaseous detonation reflection was analyzed and the velocity of reflected shock was obtained. The results show that numerical simulation and theoretical analysis qualitatively reproduce and explain the experimental phenomena. After gaseous detonation reflects on the right wall, the right-traveling rarefaction waves accelerate the reflected shock. The reason is that the shock Mach number increases and the gas flow velocity ahead of the shock decreases even though the acoustic velocity ahead of the shock decreases. Possibly due to the left unreacted or partly reacted mixture behind gaseous detonation wave, the reflected shock accelerates at low initial pressure more than at high initial pressure.