由火焰聚心和激波聚焦诱导的爆震波研究

通过对几种不同结构形式的爆震发生器进行数值模拟,研究了激波聚焦和火焰聚心现象、气动特性及其机理.数值计算采用多组分理想气体详细的化学反应机理、二维轴对称非定常流动Navier-Stokes方程来模拟流体动力学和化学动力学过程.数值计算表明用较低的点火能量对射流火焰燃烧器中可燃混合物点火,层流火焰在狭窄管壁作用下加速,射流火焰在轴线上汇聚过程有利于激波的加强,强激波加速火焰,在多重激波与火焰反复作用下,激波和火焰面之间出现热点,热点迅速放大并形成压力很高的过驱爆震波,而后衰减为稳定的爆震波,不同的激波聚焦腔爆震波的形成过程不同.通过对数值计算的结果进行分析,得到了起爆距离和稳定爆震距离,为进一步试验提供参考.

DETONATION INITIATION INDUCED BY FLAME IMPLOSION AND SHOCK WAVE FOCUSING

Computational simulations on structurally different detonation generator are carried out to study the phenomena, the mechanism and the gas dynamics characteristics of flame implosion and shock wave focusing.Two-dimensional axisymmetric and unsteady Navier-Stokes equations are numerically solved and detailed chemical reaction kinetics of hydrogen/air mixture is used. The simulation results show that the laminar flame generated by low energy spark in the jet flame burner is accelerated under the narrow channel, the jet flame impinging on the axis strengthens shock wave and the shock wave enhances flame acceleration. Under the function of multiple shock waves and flame, a number of hot spots appear between the wave and the surface. The spots enlarge rapidly, thus forming an over-drive detonation with high pressure, and then declining to stable detonation. Through calculation and analysis, the length of detonation initiation and stable detonation are obtained, thus providing the useful information for further experimental investigations.