Internal flow dynamics in a valveless airbreathing pulse detonation engine

The internal flow dynamics in a valveless airbreathing pulse detonation engine operating on ethylene fuel is studied numerically. The system involves no mechanical valves in the air flowpath, and the isolation between the inlet and combustor is achieved through gas-dynamic means. The valve operation timing for the fuel injection and initiator is determined based on the local flow conditions. The analysis accommodates the full conservation equations in axisymmetric coordinates and takes into account simplified finite-rate chemistry and variable properties for an ethylene/air/oxygen system. The detailed flow evolution and detonation dynamics during the limit-cycle operation is explored systematically. The calculated pressure history and propulsive performance agree well with experimental data. A sensitivity study of operation timing is also conducted to further elucidate the system dynamics and to provide guidelines for engine design optimization.