Adjoint-Based Design Optimization of Vortex Generator in an S-Shaped Subsonic Inlet

Abstract

This paper deals with an adjoint-based design optimization of vortex generators for the performance improvement of an S-shaped subsonic inlet, the Royal Aircraft Establishment intake model 2129. To enhance the flow quality entering the engine face maximally, the vortex generators are independently optimized with five design parameters per each vortex generator (a total of 55 design variables). To increase the design efficiency, the source term model of the vortex generator is employed. The original source term model, which does not reflect a small change in position and thus has difficulties in differentiation for sensitivity analysis, is modified into a differentiable source term model. To deal with a large number of design variables, the gradient-based design optimization method using the discrete adjoint approach is employed to minimize the distortion coefficient while maintaining the baseline total pressure recovery ratio. A total of five design cases are conducted to validate the proposed design approach, to obtain the optimized vortex generators, and to confirm their enhanced performance. Through the proposed design process, the performance of the target inlet is remarkably improved, showing that the distortion coefficient decreases well over 70% while maintaining the total pressure recovery ratio.