Optimization strategies for the design of pre-cooler based on the synergistic air-breathing rocket engine

A foundation for the engineering of pre-coolers is provided to understand the flow and heat transfer characteristics of air pre-coolers. Using the pre-cooler in the combustor of the Synergistic Air-Breathing Rocket Engine (SABRE) as the research object and selecting the smallest periodic unit of the model, numerical methods were adopted to study the flow field, outlet temperature, total pressure loss, heat transfer coefficient, and heat transfer power under the different number of tube rows, pitch, and helium/air heat capacity ratios. The number of tube rows increased from 7 to 15, the tube pitch increased from 1.5 mm to 3.5 mm, and the helium/air capacity ratio increased from 1.06 to 1.64. The results show that increasing the tube pitch reduces the outlet velocity and decreases the heat exchange efficiency, but the total pressure loss is reduced. Increasing the number of tube rows results in a linear increase in total pressure loss, but the heat exchange efficiency also increases. The increasing trend slows down when the number of tube rows exceeds 11. An increase in the heat capacity ratio can reduce the total pressure loss, increase the heat exchange power, and increase the amount of helium required. It can provide a reliable technical foundation for the practical engineering design of similar pre-coolers.