Active Control of Transpiration Boundary Conditions for Drag Minimization with an Euler CFD Solver

TLDR: In this article, an inverse optimization technique is used to manipulate the spanwise lift distribution resulting in the minimization of the induced drag on a high aspect ratio rectangular wing at subsonic and transonic flight conditions.

Abstract: The induced drag on wings is reduced at off-design cruise conditions with simulated active conformal control surface deflections modeled through transpiration boundary conditions with an Euler CFD program, the Air Vehicles Unstructured Solver (AVUS). An inverse optimization technique is used to manipulate the spanwise lift distribution resulting in the minimization of the induced drag. The method is demonstrated on a high aspect ratio rectangular wing at a subsonic and transonic flight conditions. The control surfaces deflections are calibrated to determine the extent to which their effect can be matched by a transpiration boundary condition. The CoNstrained MiNimization(CONMIN) program is used to minimize a squared error objective function. It is determined that the use of transpiration boundary conditions can drastically reduce the grid requirements and complexity associated with grid motion and deformation.