Numerical investigation on unsteady flow structure in supersonic inlet coupled with pulse detonation engine combustor

The flowfield in a supersonic inlet coupled with a pulse detonation engine(PDE) combustor and nozzle was numerically studied by an unsteady CFD method involving chemical reactions.Emphasis was placed on the flow structure of the supersonic inlet which was unsteadily interfered by the detonation wave and its reflected shock.A comparison of the performances of the three models using different coupled methods was also conducted.Results indicate that by injecting premixed fuel and oxidant into the combustor,stable and self-sustaining detonation wave is successfully generated in the combustion process.Due to the pressure perturbation caused by the detonation wave,a shock system and a reflected shock are generated in the duct.Mutual interference between them is observed,and it is found that their transformation in the duct has affected the oscillatory amplitude of the shock system.By comparing the flow characteristics of the three models with different coupled methods,it is noted that due to the buffering effect of the combustor head wall and the effect brought by the reflected shock,the two models which employ the abrupt diverging conjunction of the inlet and the combustor are able to deposit a majority of the compressed air in the combustor,which in turn significantly weakens the interference between the inlet and the combustor and makes a contribution to the stability of the inlet.Furthermore,the concave combustor head introduced can accommodate an extra volume of the high density compressed air,which results in a further reduction of the detonation-induced pressure,and leads to a larger stability margin of the inlet for the pulse detonation engine.