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临界压力是暂冲式高超声速风洞实验段流场破坏时真空罐中的压力值,临界压力比影响Ma10以上大型高超声速风洞真空系统的设计。在Φ0.3m高超声速低密度风洞中进行了Ma10以上喷管的实验,测量了风洞实验段静压、流场的皮托压力、扩压器内表面前后压力、真空罐压力等参数,了解了各部位流场随真空罐压力升高的变化过程,获得了现有风洞Ma10、Ma12和Ma16各自的流场维持所需临界压力比分别为0.34、0.35和0.5。采用FASTRAN软件模拟了风洞流场建立到破坏的非定常过程,计算结果与实验结果较为一致。临界压力比的获得为类似大型高超声速风洞真空系统设计提供了关键基础数据。
The critical pressure is the pressure in the vacuum tank when the flowfield of transient hypersonic wind tunnel is damaged. The critical pressure ratio affects the design of the large-scale hypersonic wind tunnel vacuum system above Ma10. Experiments of Ma10 and above nozzles were carried out in Φ0.3m hypersonic low density wind tunnel, and parameters of static pressure in the experimental section of the wind tunnel, Pitot pressure in the flow field, pressure before and after the diffuser inner surface, pressure in the vacuum tank, The change of flow field in each part with the increase of pressure in vacuum tank was obtained, and the required critical pressure ratios for the flow field maintenance of the existing wind tunnels Ma10, Ma12 and Ma16 were obtained as 0.34, 0.35 and 0.5 respectively. The FASTRAN software was used to simulate the unsteady process of flow field establishment to failure in wind tunnel. The calculated results are in good agreement with the experimental results. The critical pressure ratio provides key basic data for the design of a large-scale hypersonic wind tunnel vacuum system.