Drag-aeroheating multi-objective optimization design of spike-aerodisk-channel for hypersonic vehicles

To solve the challenge of drag reduction and aeroheating protection for hypersonic vehicles, multi-objective optimization method using adaptive multi-surrogate models is proposed for the spike-aerodisk-channel (SAC). In this method, Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is used to optimize the multi-surrogate models. The method then merges the pseudo Pareto sets obtained by different surrogate models. Finally, the crowded degree ranking is sorted to realize the adaptive multi-surrogate models. The flow phenomenon and aerodynamic performance of the optimized SAC are coupling analyzed. On this basis, with the objective functions of minimizing drag and average heat flux, the proposed method is successfully applied to the multi-objective optimization design for SAC. Finally, the flowfields of the Pareto solutions and the initial solution (The spike length is 74 mm, the convergence angle is 60°, and the aerospike diameter is 12 mm) are analyzed. The coupling mechanism of the multi-parameters for the SAC is revealed. The optimal solution achieves a 20.49 % decrease in average heat flux without increasing drag. Compared with the initial solution, the drag and average heat flux can be respectively reduced over 13.28 % and 41.82 %. Unlike the previous conclusions, in our study, the drag reduction and aeroheating protection effect do not continuously improve with the increment of spike length. Furthermore, the jet intensity formed through the channel mainly depends on the mass flow rate.