基于气体放电的高超声速激波结构显示技术

基于气体放电辐射强度与气体密度的相关性，在高超声速脉冲风洞FD-20中搭建了气体放电流场显示系统，并分别以平板模型、平板-方块模型和简化进气道模型为试验模型，在来流马赫数Ma=12.16、来流静压p≈106Pa的流场条件下开展气体放电流场显示技术研究。在平板实验中，气体放电方法较准确地观测到了电极之间的平板前缘激波结构，与纹影技术测得激波角相差仅为0.21°。在平板-方块实验中，气体放电方法观测到了2个截面（对称面和远离对称面截面）的激波结构，对称面波系结构与纹影和数值计算所得结果基本一致，远离对称面截面的波系结构与数值计算结果基本一致。在简化进气道实验中，气体放电方法观测到了内流道激波交叉形成的菱形结构，且尺寸与数值计算结果相差较小，约为7.9%。这些实验结果表明，在高超声速脉冲风洞中，采用气体放电方法可以获得清晰准确的激波结构，不仅可进行分截面激波结构观测，还可对被模型遮挡的内部区域激波结构进行显示，而且特别适合用于局部复杂流动波系结构的观测。

Visualization of shock wave in hypersonic flow using electric discharge

Based on the relationship of the electric discharge radiation intensity and gas density, the electric discharge visualization system was set up in hypersonic impulse wind tunnel FD-20. Three different test models are employed to explore the practicability of electric discharge for visualization of hypersonic flow structures under the flow condition of mach number Ma=12.16 and static pressure p≈106Pa. The experimental models include a plate, a combination of a cube and a plate (labeled as plate-cube), and a simplified inlet. In the plate experiment, the shock wave between electrodes was accurately observed by the electric discharge and the shlieren respectively, and the two methods gave a merely 0.21° difference in the shock wave angle. In the plate-cube experiment, flow structures on two different slices were obtained by the electric discharge. Shock structures on the central plane slice are basically the same as those obtained by the schlieren and CFD, and shock structures on the slice far away from the central plane are also confirmed by CFD. In the simplified inlet experiment, a diamond shock cell was observed by the electric discharge in the internal flow region of the inlet. The measured size of the diamond shock cell is slightly different from the numerical result with a deviation of 7.9%. These results demonstrate that electric discharge can be used to visualize shock structures on different flow slices and the internal flow region in the hypersonic impulse wind tunnel, and is especially suitable for the observation of local complex flow structures.