Adjoint Based Design Approach for Boundary Layer Ingestion Offset Intake

Abstract

The design of boundary layer ingestion offset intake is conducted by using a gradientbased optimization method. A large amount of boundary layer ingestion into flush-mounted intake on a configuration surface can cause total pressure loss and distortion. For improvement of the quality of the incoming flow into the engine, shape optimization of surface geometry at the inlet entrance is performed by using control points of B-Spline surface patch. In order to resolve the complicated flow phenomenon over a complicated geometry, the flow analysis code, sensitivity analysis code and grid modification tools are prepared for overset mesh system. Especially, overset based adjoint method is presented to deal with a lot of geometrical design parameters. For enhancing the convergence characteristics of sensitivity analysis code, a numerical dissipation for the discrete adjoint formulation is introduced. The performance of the designed geometry is evaluated by offdesign condition tests to show the capability of adjoint method for practical design problem. The physical meaning of the performance improvement by the design is elaborately investigated as well.