高超声速平板边界层流动显示的试验研究

Experimental study on flow visualization of hypersonic flat plate boundary layer

本文在高超声速脉冲式风洞内对基于纳米示踪的平面激光散射技术(nano-based planar laser scattering,NPLS)的应用进行了探索,并在此基础上对平板边界层流动结构的精细测量进行了研究.试验来流M a=7.3,总压4.8 MPa,总温680 K.通过时序的分析和调试,对各分系统实现了高精度的同步控制;定量的粒子注入及混合,实现了粒子的均匀撒播,对主流获得了均匀的显示效果;对于边界层流动,获得了精细的瞬态流动结构图像,显示了层流到湍流的转捩过程,并分析了其时空演化特性.

The classical problem of flat plate boundary layer which involves turbulence and transition is still hot, and a mass of work should be done to reach a high accuracy measurement of this flow, especially under the condition of high velocity. In the present paper, the application of the nano-based planar laser scattering （NPLS） method in a hypersonic short- duration facility is explored, and then the high accuracy measurement of a flat plate boundary layer is studied. The Mach number of the main flow is 7.3, the total pressure is 4.8 MPa, and the total temperature is 680 K. Through analysis and tests, the synchronization control of the NPLS system with the test facility is realized, and with the quantitative control, the tracer particle is uniformly seeded. Based on this, the transient boundary layer flow in the short-duration tunnel is visualized with high resolution, and the transition from laminar to turbulent flows is captured. The development characteristic of the flow is studied finally.