Characteristics of fin buffeting over delta wings

Abstract

Characteristics of fin buffeting over various delta wings was investigated by measurements of fin tip acceleration, particle image velocimetry measurements, and flow visualization. For slender wings, there is a strong asymmetry with regard to the effect of fin location on the buffeting response, and largest response occurs for the inboard fin locations. 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. The results show that single-fin buffeting may be as important as twin-fin buffeting. For a wing with low sweep angle, vortex shedding rather than vortex breakdown may become the responsible mechanism, and large buffeting excitation for outboard fin locations at a specific incidence is possible. For a double-delta wing, the interaction of strake vortices with the wing flow has a major influence on the buffeting characteristics. Finally, it was found that a nonzero fin angle did not have much effect on the conclusions arrived in this study.