高速受限混合层结构和效应实验研究

受限混合层的流动主要是喷流与自由来流相互剪切形成的混合层受到壁面的限制而形成的一种流动.文章采用后向台阶平板模型研究了高速高压比条件下的受限混合层的典型流场结构以及冷却效率.实验自由来流Mach数为5, 喷流的Mach数为1.28, 喷流总压为0.2~0.7 MPa, 通过调整冷喷气流的总压, 基于纹影流动显.形成喷口附近波系的欠膨胀流动现象的深刻认识, 提取波系特征与流动参数之间的规律.基于流动显示及实验测量结果, 通过分析流场中大尺度结构的空间演化规律, 揭示流动参数对于冷却效率的影响规律及物理内涵.采用快响应压敏漆(FRPSP)技术在高超声速风洞开展热流分布和冷却效率研究, 获得了平板对受限混合层冷却效率的影响. 

Experimental Study of Hypersonic Limited Mixing Layer Structure and Effectiveness

Limited mixing layer is the flow that between two different gases formed by the shear effects of the free stream and the jet and affected by the jet wall. In this paper the back step flat plate was used to investigate the limited mixing layer typical flow field structure and cooling efficiency at the high speed and high pressure in the hypersonic wind tunnel. The experimental free stream Mach number was 5, the jet Mach number was 1.28, and the jet total pressure was 0.2~0.7 MPa. Based on the transient schlieren photo system, it was useful to obtain the jet out shock structure changing with the flow nomenclatures by changing the jet total pressure. To obtain the mechanism of the under expansion around the jet outlet, it was necessary to get the regularity of shock system changing with flow nomenclatures. Based on the flow visualization and measurements results, regularity and physical mechanism of flow parameters effects on the cooling effectiveness were obtained. Heat flux distribution and cooling effectiveness experiments were carried out using FRPSP technique in the hypersonic wind tunnel. The relationship of cooling effectiveness and flow condition for flat plate and concave window at 0° was obtained.