Experimental evidence for non-linear growth in compressible mixing layer  

作　　者：WANG TieJin CHEN Jun SHI XiaoTian HU Ning SHE ZhenSu 

机构地区：[1]State Key Laboratory for Turbulence and Complex Systems,College of Engineering,Peking University [2]China Academy of Aerospace Aerodynamics

出　　处：《Science China(Physics,Mechanics & Astronomy)》2014年第5期963-970,共8页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11172006,10572004 and 90716008);by the National Basic Research Program of China(Grant No.2009CB724100)

摘　　要：An experimental study of compressible mixing layers(CMLs)was conducted using planar laser Mie scattering(PLMS)visualizations from condensed ethanol droplets in the flow.Large ensembles of digital images were collected for two flow conditions at convective Mach numbers Mc=0.11 and 0.47.The coherent vortices,braids and eruptions in the mixing zone were observed,interpreted as evidence of multi-scale,three-dimensional structures at a high Reynolds number.The mixing layers with a large visualized range present two stages along the streamwise direction,corresponding to the initial mixing and the well-developed stage.A new method,the gray level ensemble average method(GLEAM),by virtue of the similarity of the mixing layer,was applied to measure the growth rate of the CML thickness.New evidence for a nonlinear growth of CML is reported,providing an interpretation of previous observations of the scattering of the growth rate.An experimental study of compressible mixing layers （CMLs） was conducted using planar laser Mie scattering （PLMS） visualiza- tions from condensed ethanol droplets in the flow. Large ensembles of digital images were collected for two flow conditions at convective Mach numbers Mc = 0.11 and 0.47. The coherent vortices, braids and eruptions in the mixing zone were observed, interpreted as evidence of multi-scale, three-dimensional structures at a high Reynolds number. The mixing layers with a large visualized range present two stages along the streamwise direction, corresponding to the initial mixing and the well-developed stage. A new method, the gray level ensemble average method （GLEAM）, by virtue of the similarity of the mixing layer, was applied to measure the growth rate of the CML thickness. New evidence for a nonlinear growth of CML is reported, providing an interpretation of previous observations of the scattering of the growth rate.

关 键 词：compressible mixing layer growth rate coherent structures flow visualization 

分 类 号：O357.5[理学—流体力学]