Using Surface Sensitivity from Mesh Adjoint for Transonic Wing Drag Reduction

What is it about?

The placement of a flow control device 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 proposed to help the designer to identify the regions where drag is most sensitive to a change of the surface of a transonic wing and to assess the success of an optimisation. An array of shock control bumps are deployed in the areas of high sensitivity and optimized using a gradient based approach. In addition to the sensitivity in the shock regions, a non-shock region is also identified using the sensitivity map on the wing. This region is not apparent from surface flow properties, such as pressure or skin friction, and could be overlooked by a designer without the sensitivity map.

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Why is it important?

The results show that the mesh adjoint approach successfully identifies drag sensitive areas on the wing and assists in the deployment of the bump arrays. The bumps are parametrised using class/shape function transformation (CST), which provides a highly flexible design space, with a large number of design variables, to achieve an optimal solution.