凹面腔内激波聚焦起爆爆震波过程的数值模拟

Numerical investigation of detonation initiation by shock wave focusing over paraboloid reflector

关键词:  脉冲爆震发动机  爆轰  激波  爆轰波  数值模拟

Key words:  Pulse detonation engine  Detonation  Shock wave  Detonation wave  Numerical simulation

摘要:

运用CFD方法和基元反应机理对环形向心射流产生的激波在凹面腔内的反射聚焦起爆爆震波过程进行了数值模拟,并根据流场分布及变化情况分析了激波聚焦及其在H2-Air混合物中起爆爆震波的全过程。对于本文建立的模型,起爆点在抛物形壁面的底部顶点处,聚焦起爆爆震波后的瞬间压力达到21.3MPa,温度达到4540K。爆震波在凹面腔内向开口端传播过程中仍会出现两次聚焦,压力达到约18MPa,温度达到4000K左右。研究结果表明:利用环形向心射流产生的激波在凹面腔内聚焦可以成功直接起爆爆震波,是一种有效的爆震直接起爆方法。

Abstract:

Detonation initiation by annular centripetal jet induced shock focusing over paraboloid reflector was simulated with the help of kinetic mechanism of hydrogen combustion and CFD method.The processes of shock focusing and its ignition of detonation were analyzed according to the distribution and development of pressure,temperature and OH mass fraction in the flow field.In the simulation the ignition point located at the vertex of the paraboloid reflector.And the high pressure reached 21.3 MPa;high temperature reached 4 540 K at the moment when detonation was ignited at the focus.Two other focusing processes would come into being accompany the detonation propagation in the paraboloid reflector reaching a high pressure of about 18 MPa and a high temperature of about 4 000 K.The result shows that annular centripetal jet induced shock focusing over concave reflector can ignite detonation directly and is an effective method of direct detonation ignition.