爆震发动机扩张型引射喷管的非定常流动过程研究

Computational Study on Unsteady Flows in a Diverging Ejector for Pulse Detonation Engine

为揭示PDE引射喷管的瞬态流动机理,采用带化学反应的非定常仿真方法,对使用二维扩张型引射器PDE的非定常排气过程进行分析,获得了流场结构的瞬态演化过程,并将其单循环的积分冲量与无引射喷管状态进行了对比。结果表明,仿真中形成了稳定的爆震波,其主要特性参数与理论值相差较小,并且仿真获得爆震排气过程的流动结构与试验结果吻合良好。带引射器PDE的单循环主要流动过程可以分为:爆震波产生和排出阶段、引射器主动进气阶段、爆震管第一次倒流阶段、爆震管主动排气阶段、爆震管第二次倒流阶段。相比无引射器状态,使用扩张型引射器可以使PDE单循环积分冲量增加21.76%,并且其对爆震管头壁压强、单次循环周期无明显影响。

Utilizing the unsteady CFD method with chemistry reaction,the unsteady exhausting process in a pulse detonation engine（PDE） equipped with a two-dimensional diverging ejector is analyzed to reveal the underlying unsteady flow mechanism. The transient flow structures in the ejector are carefully examined and the integral impulse of a single cycle of the system is compared with the non-ejector case. According to the computational results,a steady detonation wave is formed in the PDE combustor,of which the critical parameters are close to the theoretical ones. Also,the calculated flow structures of the exhausting process agree well with the experimental results. The flow process of a typical cycle of the PDE with ejector can be divided into five main phases,namely,detonation wave generation and exhausting phase,ingesting phase for ejector,the first reversed flow phase for PDE combustor,actively exhausting phase for PDE combustor,the second reversed flow phase for PDE combustor. As compared with the non-ejector case,the integral impulse of a single cycle of the PDE with ejector is enhanced by 21.76% and the pressure history of the head wall and the cycle length are basically unchanged.