Integrated design method of the waverider forebody and inward-turning inlet based on genetic/gradient hybrid strategy

The integrated design of the waverider forebody and inward-turning inlet has been applied to the hypersonic air-breathing aircraft design. Traditional integrated design methods typically design the global performance-influencing factors by parameter analysis or intelligent algorithms first, and then perform the non-uniform or viscous corrections. However, the strong internal–external flow coupling and inadequacy of two-dimensional corrections to consider three-dimensional flow field effects limit full consideration of these factors. To further consider these factors and enhance the design flexibility, this study proposes a staged design method based on the hybrid strategy. At the global parameter design stage, the genetic algorithm is employed to thoroughly explore the design space of both internal and external flow parameters, while accounting for performance indicators of the forebody-inlet coupling. At the local surface refinement design stage, the discrete adjoint gradient algorithm is applied to design the local surface to mitigate the negative impacts of inflow non-uniformity and viscous effects. Finally, a Mach 5 integrated design case is realized. The proposed method achieves a configuration with higher comprehensive performance than that based only on the genetic algorithm. The mass flow coefficient increases by 1.48%, the non-uniformity induced by the forebody reduces by 44.51% at the symmetry plane, the exit total pressure recovery coefficient increases by 4.77%, the exit pressure rise increases by 3.57%, and the exit flow distortion reduces by 3.72%. Furthermore, the performance improvement mechanisms are obtained by analyzing the strategy of mitigating the adverse impacts of inflow non-uniformity and viscous effects. Therefore, the proposed method can be used in the design of hypersonic air-breathing aircraft in the future.