Vortex evolution and flame propagation driven by oblique shock wave in supersonic reactive mixing layer

Abstract

Vortex evolution and flame propagation of supersonic reactive mixing layer with the interaction of single/double oblique shock waves are researched by employing direct numerical simulation methods. The vortex dynamics are found to be modulated by oblique shock waves, resulting in mixing enhancement of vorticity values. Notably, wider range of vortex scale distribution induced by double oblique shock waves leads to intense entrainment and nibbling process of large and small scale structures, which can remarkably increase the mixing level of hydrogen and airstreams. The analysis of vorticity transport equation indicates that compressing effects induced by shock waves are responsible for the increase of vortex strength. By tracking the vortex braid dynamical evolution process, it is revealed that local auto-ignition induced by double shock waves can accelerate the consumption of hydrogen and finally lead to high efficiency combustion. Since complex background waves are inherently present in confined space of Rocket-based Combined Cycle (RBCC) engine, the newly observed mixing enhancement mechanism for double shocked-reactive mixing layer can provide a guidance for the future design of mixing strategy using the inherent wave structures in RBCC combustor chambers.