高超声速发动机碳氢燃料预冷器换热特性

Introducing a pre-cooling process into the air intake of a hypersonic turbine engine can reduce the temperature of the air entering the compressor and increase the available pressure ratio and the engine thrust. To study the thermodynamic performance of the precooler, the structure and heat exchange of the precooler have been investigated in detail, and a segmented thermodynamic calculating model for an involute precooler using high heat sink hydrocarbon fuels as the cold source is established. Results suggest that the thermodynamic calculation for a precooler must be performed in segments when both cold and hot fluids experience large temperature variations. The influence of the fuel mass flow rate, air outlet temperature, and precooler structural parameters on the thermodynamic performance of the precooler are studied. A tremendous amount of micro heat exchange tubes lead to almost laminar flows in the tube. With the increase of the fuel flow rate, the cooling capacity of the precooler is enhanced, and the weight is reduced, but the fuel after heat absorption might not be totally used for combustion, resulting in thrust waste. Lowering the air outlet temperature helps improve the engine thrust performance, but will increase the precooler weight and air pressure loss. When the transverse and longitudinal pitches of the tube bundle both are 1.5 times of the tube diameter, compared with the staggered arrangement, the air-side convection heat transfer capacity for the in-line arrangement deteriorates, and the precooler weight and air pressure loss are both larger. The transverse and longitudinal pitches of the tube bundle have complicated influence on the thermodynamic performance of the precooler. This work can provide strong support for the design, verification, and performance analysis of the tube bundle precooler with similar structures in the future.