Computational study on unsteady flows in a diverging ejector for pulse detonation engine

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.