超/亚声速混合层压力不匹配时流动特征

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

关键词:  压力不匹配  超/亚声速混合层  流动特征  剪切层  组合动力推进

Key words:  Unmatched pressure  Supersonic/subsonic mixing layer  Flow characteristics  Shear layer  Combined cycle propulsion

摘要:

为了获得压力不匹配对超/亚声速混合层空间分布与增长、压力分布和相似性等特征的影响规律，开展试验和数值模拟研究。通过粒子图像测速技术PIV测量混合层空间分布，标准k-ω模型模拟稳态流场特征。超声速气流马赫数为1.32，亚声速气流马赫数为0.11，五组不同压比分别为0.82，0.95，1.11，1.22和1.47。研究结果表明：压力不匹配对混合层增长的影响较弱；当压比>1时，混合层沿流向呈现波纹分布，静压呈现高、低压交替分布；压比增加，混合层内无量纲速度分布不变，无量纲总压减小，而湍流强度增加。基于无粘假设的预测模型捕捉了波节的基本结构与分布。

Abstract:

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.