Buffeting of a flexible fin over a delta wing

Buffeting of a flexible fin due to the leading-edge vortex flow over a delta wing was investigated. Tip acceleration of the fin as well as unsteady wing surface pressure were measured to understand the interaction of the fin with vortex breakdown. There is a strong asymmetry with regard to the effect of fin location on the buffeting response. For outboard fin locations, the buffeting is small, even at high angles of attack when vortex breakdown is well upstream. For inboard fin locations, the largest fin vibrations were found for breakdown locations well upstream of the fin, and when the shear layer of the breakdown region impinges on the fin. Maximum buffeting response occurs when the fin is located near the vortex axis for low angles of attack, but the location of the maximum buffeting shifts to inboard locations as the angle of attack is increased. The results show that single-fin buffeting may be as important as twin-fin buffeting. The effect of fin flexibility is likely to be negligible when the fin buffeting over aircraft becomes important.