Analysis of an Air-breathing Pulsed Detonation Engine with Bypass and Ejector

For an air-breathing pulse detonation engine with single detonation tube, two ways are applied currently to achieve quasi-steady state at its inlet: introducing acoustic cavity or supersonic throat at the head of detonation tube. But the former needs much larger acoustic cavity and the latter needs much longer inlet. Combining the advantages of these two devices, a configuration of air breathing pulsed detonation engine (APDE) with bypass and ejector concept was analyzed in this paper. It is composed of supersonic inlet, acoustic volume, detonation chamber, bypass, and ejector that include mixing chamber and common nozzle. To analyze the influence of bypass and ejector on performance, a global, single-step, reduced chemistry mechanism and AUSM time-marching algorithm are used to simulate 1-D APDE. The calculated results show that the performance of APDE is determined by two factors: shock loss induced by the throat and diameter of nozzle for bypass and mass flow distributions. If there is a reasonable configuration of APDE with bypass and mix exhaust, it will stabilize the inlet, decrease the loss of total pressure and enhance the propulsion performance. A 2-D flow evolution using traditional upwind scheme is simulated with 3-order TVD property and Strang-splitting method with a detail chemical mechanism to simulate a full cycle process of APDE with bypass and ejector. It shows that if there is no valve on the exit of bypass duct, the backflow will influence the flow field of bypass and result in the decreasing of mass flow on the bypass, then decreasing the performance of APDE. Another two methods may improve the disadvantage of no bypass valve. It suggests the current configuration could be further refined to provide more efficient bypass and mixing chamber.