可压缩混合层密度梯度场特性的实验研究

利用纹影技术研究了不同对流马赫数（Mc=0．28，0．38，0．72）可压缩混合层密度梯度场的特性。由纹影图像可以看出：具有可压缩效应（高M。数）的混合层存在不同程度的摆动。将纹影图像对比以后还发现：当Mc〈0．3时，在可压缩混合层中发现了类似于Brown—Roshko的结构，混合层看不出明显的摆动；随着可压缩效应的增强（对流马赫数Mc〉0．3），混合层开始摆动，并且随着对流马赫数的增大，混合层开始摆动位置向前移动。此外，还观察到不同对流马赫数下大尺度结构出现的区域有不同的特点。

Experimental research on characteristic of density gradient in a compressible mixing layer

Using sehliren technique, the characteristic of density gradient in a compressible mixing layer was investigated at different convective Mach numbers （Mc=0. 28, 0.38, 0. 72）. The instantaneous schlieren images show that a compressible mixing layer begins to swing at higher Mc number. Compared the sehlieren images at different M, numbers, structures similar to Brown-Roshko have been observed for Mc〈0.3. In addition, the compressible mixing layer begin to swing with the increase of compressibility effect （convective Mach number Mc〉0. 3）. And then the location beginning to swing moves forward when the eonvective Mach number increas- ing. Moreover, the region with the existence of a large-scale structure at different Mc numbers has different characteristics.