可压缩混合层交界面附近湍动能特性的实验研究

Experimental research on characteristic of turbulent kinetic energy at the interface between compressible mixing layer and free stream

利用粒子示踪、粒子图像测速(PIV)和纹影技术研究了对流马赫数Mc=0.38时大尺度结构主导的可压缩混合层界面特性,主要是超-亚声速来流与混合层交界面附近湍动能的增长率特性。研究结果表明:在混合层交界面附近,湍动能发展所需能量主要来自当地流体微团的可压缩性,占主导地位的是雷诺应力通过流向线变形向流体微元的输入功;而混合层内部则以雷诺应力通过流向剪切变形引起的输入功为主;此外,交界面附近的大尺度结构对流体微元的线变形输入功具有抑制作用。

Using PIV （particle image velocimetry） and schliren technique, the characteristic of interface, specially growth rate of turbulent kinetic energy, between free stream and compressible mixing layer at con- vective Mach number Mc=0. 38 has been investigated. The results show that the increase or decrease of tur- bulent kinetic energy mainly derivates from the compressibility of fluid particle near the interface. The work resulting from streamwise linear strain of averaged velocity plays an important role of turbulent kinetic ener- gy near the interface. It seems that the existence of large-scale structure suppresses the change of turbulent kinetic energy near the interface.