Vortex structures evolution in supersonic mixing layers with different inlet Reynolds numbers based on the Lagrangian method

The supersonic mixing layer is a typical flow structure in an aircraft’s optical seeker. The free incoming flow and cooling jet form a mixing layer through shearing. In most cases, the flow has become a fully developed turbulent due to complex factors during flight. This paper mainly focuses on the influence of the inlet Reynolds number on the development of the supersonic mixing layer. The rescaling/recycle method is used to generate turbulence at the inlet of the mixing layer. The results show that when the turbulence of the high-speed flow is strong, the transition position of the mixing layer will be advanced and the mixedness will be enhanced. The mixing efficiency is high at the position corresponding to the vortex in the mixing layer. Finally, the Lagrangian coherent structure and particle tracking methods are used to analyze different mixing processes, and the entrainment characteristics of the vortex are studied.