Multi-objective optimization of a pulse detonation ramjet combustor based on response surface methodology and NSGA-Ⅱ

The development of hypersonic vehicles has raised stricter performance requirements for propulsion systems. With the distinctive performance advantages, the pulse detonation ramjet has become a promising technical route in the field of hypersonic propulsion. To achieve superior performance of a pulse detonation ramjet combustor, a multi-objective optimization framework is proposed for combustor structure optimization. First, a numerical simulation platform is established, and the accuracy is verified. Thereafter, numerical design of experiments (DOE) is carried out. Based on the DOE results, the detonation initiation and propagation processes are analyzed, sensitivity analysis is implemented, and a response surface methodology surrogate model is constructed for optimization work. The optimization objectives are to minimize the time required for the detonation wave to reach the combustor outlet ( t_d ) and maximize the average outlet total pressure during the exhaust process ( P_t,e ). Four combustor structural parameters, namely cavity depth, cavity length, rear wall angle and expansion ratio, are selected as optimization variables. The NSGA-Ⅱ is adopted to solve multi-objective optimization problems and obtain the Pareto solution set. Two optimal combustor configurations are acquired via the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) under two weighting strategies: Equal Weight (EW) and Entropy Weight (SW). Compared with the reference combustor, the configuration optimized by SW-TOPSIS achieves a 1.52% relative growth of P_t,e without increasing t_d , which realizes the improvement of combustor performance. The multi-objective optimization framework proposed in this study can serve as a reference for the optimal design of detonation combustors and other related fields.