基于 NSGA-Ⅱ的超燃冲压发动机再生冷却通道多目标优化研究

The aerodynamic thermal load increases sharply when SCRamjet is flying at high Mach number. But the coolant carrying capacity is strictly limited, and the cooling of engine thermal structure is faced with severe challenges. The key technology to alleviate the cooling challenge of SCRamjet engine is to optimize the structure of regenerative cooling channel and improve the utilization rate of onboard coolant heat sink. The study focused on the problems of unreasonable coolant flow distribution and high local overtemperature risk in SCRamjet engine high thermal environment. Three optimization strategies were proposed, including the aspect ratio and position of the channel along the engine circumference, and tsynchronous design and independent design of the position and size of the interconnection structure along the axial direction. Taking n-Decane as a typical hydrocarbon fuel, parametric modelling of regenerative cooling channels was performed in the supercritical temperature zone. The maximum wall temperature of heating surface and the relative deviation of outlet fuel temperature were taken as the objective function. The multi-objective optimization design was carried out based on NSGA-Ⅱ and RNFNN agent model, and the global Pareto Front optimal solution set was obtained. The results showed that the multi-objective optimization of regenerative cooling channel based on NSGA-Ⅱ can effectively optimize the cooling effect, reduce the thermal structure temperature and alleviate the cooling challenge of scramjet engine without increasing the coolant.