比热比和压比对高超飞行器尾喷流影响的实验研究

采用比热比为1.25的四氟化碳和空气的混合气体，模拟了超燃冲压发动机出口高温燃气的比热比。采用模型内喷管模拟发动机内喷流，风洞流场模拟飞行器外流。在0.5m常规高超声速风洞中，建立了模拟吸气式高超飞行器热态尾喷流干扰研究的实验手段，开展了喷流比热比对吸气式高超声速飞行器后体区域气动性能影响的实验研究。比较了相同外流和喷流落压比条件下，纯空气和混合气体喷流在喷流干扰区域的压力分布及流场结构。结果显示，混合气体喷流和空气喷流在喷流干扰区域的流场及表面压力分布差别明显。实验证实了喷流比热比是一个不可忽视的重要因素，在研究吸气式高超声速飞行器喷流干扰问题时应准确模拟。

Experimental study of the influence of the specific heat and pressure ratios on the hypersonic vehicle's nozzle plume

The experimental studies have been carried out to explore the influences of the Specific Heat Ratio (SHR) on the air-breathing hypersonic vehicle's nozzle plume at CARDC's 0.5m hypersonic wind tunnel. The SHR of the plume at the scramjet exit is simulated by CF₄+Air with SHR=1.25. The Laval nozzle is used in the experimental model to generate the supersonic nozzle plume and the flow field generated by the wind tunnel is used to simulate the model's external flow field. The differences of the pressure distributions and flow field structures are compared between the pure air and mixture gas plumes. Results show that in the mixture gas plume, the pressure distributions are higher than air plume in the core and interaction regions. The SHR is one of the key parameters for the study of air-breathing hypersonic vehicle's plume.