螺旋管式空气-空气换热器的设计和实验研究

Design and Experimental Study of Spiral Tube Air-Air Heat Exchanger

关键词:  螺旋管  换热器  航空发动机  热防护

Key words:  Spiral tube  Heat exchanger  Aero-engine  Thermal protection

摘要:

为解决飞行器高马赫数飞行时，用于冷却航空发动机涡轮叶片和其它高温部件的压气机出口空气温度过高的问题，设计加工了一种以外涵空气为冷源的螺旋管式空气-空气换热器用于预冷冷却空气。换热器由48根材料为不锈钢321，外径4mm，壁厚0.5mm的螺旋管组成，重量1.91kg，传热面积密度106m²/m³。在常温工况下，实验研究了换热器管内和管外流体的阻力特性，高温条件下试验验证了换热器设计点性能，压气机出口空气温降达188K，功重比4.9kW/kg。高温条件下实验研究了两侧空气流量分别单独变化时换热器的热动力性能，拟合了管外换热经验关系式。研究结果可用于未来相似结构换热器的设计。

Abstract:

To solve the problem that the temperature is too high of the compressor bleeding air used to cool the turbine blades and other high temperature components of the aircraft engine when flying at high Mach number， a spiral tube air-air heat exchanger with bypass air as a coolant was designed to pre-cool the cooling air. The heat exchanger consists of 48 pieces of stainless steel 321 spiral tubes with the outer diameter of 4mm and wall thickness of 0.5mm. The weight is 1.91kg and the heat transfer area density is 106m²/m³. The flow resistance characteristics of the fluid inside and outside the heat exchanger tube were studied experimentally under room temperature conditions. The design point performance of the heat exchanger was verified by the test under high temperature conditions. The temperature drop of the compressor exit air reached 188K and the power-to-weight ratio was 4.9kW/kg. Under the high temperature condition， the thermodynamic performance of the heat exchanger was studied experimentally when the air flow on both sides was changed separately， and the empirical correlation for heat transfer coefficient on tube outside was fitted. The research results will be helpful for the design of similar structure heat exchangers.