来流边界层拟序结构对超声速混合层流场结构的影响研究

超声速混合层涉及可压缩湍流的根本问题,具有重要的应用背景。通过设计超声速混合层实验装置、应用新近提出的高分辨率NPLS测试技术,拍摄了来流边界层分别为层流和湍流流态下混合层的流向和展向流动图像。根据流动图像的特征,分析了混合层的流向与展向流场切面中拟序结构的成因;深入讨论了来流边界层中拟序涡结构与混合层涡结构的相互作用问题;比较了层流和湍流来流条件下混合层拟序结构的异同及其对混合效率的影响。结果表明：当来流边界层为湍流时,对应的混合层具有较高的混合效率。

Experimental study of influence of the coherent structures of inflow boundary layer on supersonic mixing layer flow field

Supersonic mixing layer involves the fundamental problems of compressible turbulence,and is important in many applications.Here,by designing supersonic mixing layer apparatus carefully,and applying the recently proposed NPLS technique,the flow images of streamwise and spanwise supersonic mixing layer for laminar and turbulent inflows were captured.According to the flow images,the origination of coherent structures in streamwise and spanwise slices was analyzed.The interaction between the vortices in mixing layer and the coherent structures in the inflow boundary layers were discussed.By comparing the laminar and turbulent inflows,the difference of coherent structures and their influences on the mixing efficiency were studied.The result shows that the turbulent inflow corresponds with higher mixing efficiency.