壁面温度对高超声速边界层转捩影响的实验研究

The very high wall temperature caused by the high speed aerodynamic heating is one of the important factors that affect the transition on the hypersonic vehicle. There exist multi-mode instabilities, including the first and second mode, in the hypersonic boundary layer. Because the wall temperature has opposite effects on each growth rate of the two modes, the effect of the wall temperature on the transition is not sure. This program has two targets. The first is to develop quiet wind tunnel test techniques which apply to the high temperature environments. The second is to experimentally investigate the transition location, disturbance evolution and flow structures under different wall temperature conditions caused by heating in the hypersonic quiet wind tunnel. Combined with the theoretical and numerical methods, an analyses will be given on the mechanism through which the wall temperature affects the transition.

高超飞行器表面由于气动加热而产生高温是影响转捩的重要因素。由于高超声速边界层存在以第一和第二模态为主的多种不稳定模态，而壁温变化对于上述两种模态增长影响恰好相反， 所以壁温对于高超转捩位置的影响比较复杂。本项目目标有二：一，在先期研究基础上发展高温环境下高超声速静风洞测试技术；二，在高超声速静风洞中开展实验，系统研究壁面加热引起壁温变化对边界层转捩位置、扰动演化以及流动结构的变化的影响，并结合理论和计算方法，分析壁温影响转捩的物理机制。

壁温是影响高超声速边界层层流-湍流转捩的重要问题。过去关于壁面加热（壁温高于绝热壁温度）对转捩影响的研究非常少。本项目研究内容包括发展高温环境下高超声速边界层转捩预测和扰动测量技术和运用实验方法研究壁温加热对260mm 长裙锥上Ma 6边界层转捩的影响。主要结果如下：1. 红外测量技术的边界层转捩预测技术和基于聚焦差分干涉技术的扰动测量技术可有效运用于壁温300K~900K的测量中。2. 壁温增加将促进第一模态波增长并抑制第二模态波的发展。3. 当壁温在温度时，边界层转捩最晚。从300K上升至绝热壁温度，边界层转捩不断延迟；而当壁温从绝热壁上升至900K时，转捩不断提前。