超声速混合层中扰动增强混合实验

以基于纳米技术的平面激光散射(nano-based planar laser scattering, NPLS)流动显示技术定性研究了隔板扰动对超声速混合层($Mc=0.5$)的混合增强效果. 首先通过系列实验优化设计了扰动参数. 实验结果表明，超声速混合层对于从隔板引入的扰动非常敏感. 二维扰动的混合强化机制是提前混合层失稳位置，增厚混合层；而三维扰动的混合强化机制主要是通过诱导流向涡和展向运动，促进流动三维性质的发展. 总体而言，三维扰动的混合强化效果优于二维扰动. 由于是超声速混合层，隔板上的扰动片虽然很薄，但同样会引起激波的产生，是该方法中总压损失的主要原因. 

EXPERIMENTAL STUDY ON PERTURBATION MIXING ENHANCEMENT IN SUPERSONIC MIXING LAYERS

Perturbation mixing enhancement effects are evaluated for supersonic mixing layers by NPLS flow visualization technique. Some experiments are carried out to optimize the parameters of the disturbances. The images reveal that the mixing layers are sensitive to the disturbances within the splitter plate. 2D disturbances advance the unstable position of the mixing layer and thicken it to enhance mixing, while 3D disturbances promote flow 3D characteristic to enhance mixing by inducing streamwise vortexes and spanwise convolution. The mixing-enhancement effect of 3D disturbances is better than that of 2D disturbances. Although the tape is located in the sub-boundary layer, the shock wave is inevitable in the supersonic flow. These Mach waves are the main reason for the loss of total pressure in this mixing-enhancement method.