螺旋管式空气-空气换热器的设计和实验研究

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.