The efficient mixing of fuel and air at supersonic speed is the main challenge of scramjet technology. Based on analysis of large eddy simulation and hydrodynamic stability, the methods of mixing enhancement are studied in the supersonic wake shear flow. The existence of a wake component alters the profile of mean velocity, and has an important influence on the hydrodynamic stability. The existence of a wake component makes the most unstable modes of mixing layer from the three-dimensional to the two-dimensional, and the frequency and growth rate of the most unstable wave increase. The method of mixing enhancement of introducing disturbances in the mixing layer is still effective based on the analysis of hydrodynamic stability. According to the stability analysis, the parameters of wavy wall are designed. The numerical simulations observe that the disturbance introduced by the two-dimensional wavy wall cannot grow and almost has no mixing enhancement effect, while the disturbance introduced by the three-dimensional wavy wall can grow rapidly and has mixing enhancement effect. The closer the parameter of the wavy wall is to the parameter of the most unstable disturbance, the more obvious the mixing enhancement effect is.
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