Numerical investigation on mixing enhancement of the cavity with pulsed jets under oblique shock wave interference

Abstract

In this investigation, the impact of steady jets and pulsed jets at various frequencies on mixing performance is studied to achieve adequate mixing in the cavity-based combustion chamber disturbed by the oblique shock wave. The pulsed ethylene jets are simulated numerically employing the SST k–ω turbulence model and unsteady RANS. The grid-independence verification is first performed, which is in accordance with the experimental data of wall pressure. The flow structures, mixing efficiency and jet penetration of steady jets and pulsed jets are compared and analyzed. The pulsed jets facilitate the mixing of ethylene in contrast to the steady jets, especially in the near field of the jet. Pulsed jets improve the penetration depth of lower jet-to-crossflow pressure ratio steady jets, but the advantage in this regard is limited as the frequency increases. Among the pulsed jets considered in this study, the 200 kHz pulsed jet has the best mixing coefficient, but the 50 kHz pulsed jet is optimal at the penetration depth. Hence, the pulsed jet with appropriate frequency can simultaneously achieve a larger penetration depth and a more desirable mixing efficiency.