Using surface sensitivity from mesh adjoint solution for transonic wing drag reduction

Shock control bumps are a promising device for improving the aerodynamic efficiency of transonic aircraft. From the literature, the peak location and bump height are the most sensitive parameters, therefore the deployment position and size of the shock control bump are key factors. When placing a flow control device it is highly dependent on the designers’ experience and their view of the area where the device will be most effective. In this paper, the mesh adjoint approach is employed to identify the regions where the drag coefficient is sensitive to a change of the wing surface. An array of shock control bumps are then deployed in the areas of sensitivity and optimized using a gradient based approach. In addition to the sensitivity in the shock regions a non-shock region is identified using the sensitivity map on the wing. This region is not identified in other plots such as pressure or skin friction and could be overlooked by a designer without the sensitivity map. The results show that the mesh adjoint approach successfully identifies the drag sensitive areas on the upper wing and assists in the deployment of the bump arrays quickly, and the class/shape function transformation (CST) bump provides a highly flexible design space, with a large number of design variables, to achieve an optimal solution.