Flow Characteristics of Supersonic-Subsonic Mixing Layer under Unmatched Pressure Conditions

Both experimental and numerical investigations have been conducted to investigate the effects of unmatched pressures on the spatial development, pressure distribution and self-similarity of the supersonic-subsonic mixing layer. PIV technique is employed to measure the spatial distributions of the mixing layer in conjunction with the standard k-ω turbulence model considering the effect of compressibility adopted to simulate the flow characteristic of mixing layer. The Mach numbers of the supersonic and subsonic streams are 1.32 and 0.11, respectively. Five different pressure ratios of 0.82, 0.95, 1.11, 1.22 and 1.47 are considered to investigate the pressure dependence of flow characteristics. Results show the unmatched pressures have little effects on the growth of mixing layer. When the pressure ratio is larger than 1, the mixing layer exhibits a wave-like shape and a row of alternate low pressure and high-pressure regions are developed along the streamwise direction. As the pressure ratio increases, the non-dimensional velocity in the mixing layer does not change, the non-dimensional total pressure decreases while the turbulent intensity increases. With the inviscid flow assumption, an analytic model is proposed for the prediction of wave nodes characterizing the distribution of the pressure waves. © 2022, Editorial Department of Journal of Propulsion Technology. All right reserved.