Study on the Mixing Performance of Pulse Injection in a Supersonic Combustor

Three-dimensional numerical simulations are used to investigate the mixing performance of pulse injection in a supersonic combustion chamber. The influence of complex nozzle configurations is excluded, and the effects of pulse dynamics on mixing performance are examined. The results show that the mixing performance of the pulse injection has a periodic variation. Based on the coupling analysis of the numerical flow field structure and the penetration depth, it is found that the main factor governing changes in pulse penetration depth is the development of the near-nozzle flow field. By comparing the mixing performance trends and flow field coupling characteristics of sinusoidal and square-wave pulse injection, the proposed mechanism governing penetration depth is further verified, and the square-wave pulse injection shows an obvious mixing advantage. Therefore, this article further explores the mixing law of square-wave pulses under different duty cycles, identifies distinct mixing regions in the duty cycle–frequency parameter space, and obtains the optimal performance curve for the pulse parameters. This paper goes beyond comparisons of a few discrete frequencies reported in previous studies. By studying those factors, the frequency-dependent behavior of pulse injection is explained in terms of its underlying mechanism. By comparing different waveforms, the mechanism is further verified, and its applicability is further examined. These results provide a physical explanation for the observed mixing trends.