气流出口型面对凹面腔内激波聚焦起爆的影响

为提高两级脉冲爆震发动机工作的可靠性，探寻强化凹面腔内激波聚焦起爆爆震波的方法，通过数值模拟，采用氢气作为燃料、空气作为氧化剂，探讨了3种凹面腔气流出口型面及出口面积对激波聚焦起爆的影响。结果表明:采用垂直出口壁面有助于提高凹面腔内的激波聚焦起爆压力和温度，使起爆时刻提前，随着出口面积的减小，激波聚焦峰值压力有较大的提高；但效果不如垂直壁面，随着倾斜壁面出口面积减小，起爆点的压力和温度只有小幅度增加，起爆时刻基本无变化；采用弧形出口壁面，不能对向凹面腔底部传播的激波产生反射强化作用，不能有效起爆爆震波。对比3种出口壁面型面，垂直壁面能更有利于凹面腔内的能量聚集，强化激波聚焦起爆爆震波。 

Influence of flow outlet surface shape on detonation initiation via shock wave focusing in cavity

To improve two-stage pulse detonation engine''s operational reliability, a method of enhancing detonation initiation via shock wave focusing was explored. Numerical simulation was conducted, hydrogen was used as a fuel and air as an oxidizing agent. Influences of 3 outlet surface shapes and various exit areas on shock wave focusing were discussed. Results indicated that vertical outlet surface was helpful to increase the pressure and temperature of shock wave focusing and make it occur ahead of focusing time. Pressure of focusing point increased as exit area decreased. Tilting outlet surface was inferior to vertical outlet surface, pressure and temperature of focusing point increase little. Curved exit surface was not helpful to increase the pressure and temperature of shock wave focusing, and detonation wave was not initiated. Compared with 3 outlet surface shapes, vertical outlet surface was better. Simulation results provided a reference for experiment design.