Characteristics of Nonequilibrium Radiation behind Strong Shock Waves in Low-Density Air

利用自由活塞双隔膜激波管同时观测12 km/S超高速激波后空气总辐射及其光谱辐射的紫外诊断系统，对低密度空气中强激波后的非平衡辐射特性进行了实验研究。对自由活塞、双隔膜激波管的流动和工作特性进行了数值模拟和实验研究。从计算结果可以看出，压缩过程和膜片破裂时间对总管特性有影响。这些结果提高了管数据的总再现性。同时测量了低密度空气中强激波后非平衡化学反应空气中的总辐射和光谱辐射。在结果中，阐明了单峰到双峰强度的总辐射分布，以反映测试气体中污染物来自化学反应的辐射的可能性。利用新型激波管仪器和气体监测系统对试验段和试验气体的净化条件进行了改进实验，得到了更准确的紫外光谱和总辐射数据。从测试气体成分影响的角度对得到的辐射分布进行了讨论。采用耦合热化学非平衡的Navier-Stokes方程对平板强激波诱导流动中的辐射现象进行了数值分析。结果表明，激波诱导边界层中存在强烈的非平衡辐射。

Nonequilibrium radiation characteristics behind strong shock waves in low-density air is experimentally investigated by the ultraviolet diagnostic system for simultaneous observation of the total radiation and its spectral radiation of the air behind the hypervelocity shock wave of up to 12km/s by using the free-piston, double-diaphragm shock tube.1. The characteristics of the free-piston, double-diaphragm shock tube flows and tube operation is investigated numerically and experimentally. From the results obtained it is elucidated that there exist the effects of compression process and diaphragm rapture duration on the total tube characteristics. Total reproducibility of the tube data has been increased by these results.2. Simultaneous measurements of total radiation and the spectral radiation in the nonequilibrium, chemically reacting air behind the strong shock waves in low-density air are performed. Among the results the total radiation profiles of one-peak to two-peaks in strength are elucidated to reflect the possibility of radiation from the chemical reactions by contaminants in test gas.3. Doing the improved experiments by purified conditions of the test section and the test gas by new instruments of shock tube and gas monitoring system, the more precise data of ultraviolet spectral and total radiation are obtained. The obtained radiation profiles are discussed in view of test gas composition effects.4. Numerical analysis for radiation phenomena in the strong shock induced flow along a flat plate is investigated by Navier-Stokes equation coupled with thermochemical nonequilibrium. The results indicates the existence of intense nonequilibrium radiation in shock induced boundary layer.