Support Interference for a Maneuvering Delta Wing

The results of a recent investigation of support interference in dynamic wind-tunnel testing are presented. Particular emphasis has been focused on studying the interaction of vortices generated by delta wing models at high angle of attack with a support structure. A novel approach was used whereby the effects of time-varying vortex strength could be separated from the effects of the vortex-support interaction. With this approach, it was shown that the principal effect of support interference was to cause an upstream shift in the mean breakdown location, regardless of the form of motion or forcing frequency. The magnitude of the fluctuations in the breakdown location was shown to be dictated by support interference at low forcing frequencies, but by time-varying vortex strength effects at high frequencies. A number of important observations were also made of the vortex behavior at high forcing frequencies. In particular, a curious jumping behavior of the vortex breakdown location was observed. The presence of the support reduced the magnitude of the breakdown jump, but jumping was, nevertheless, observed in all of the cases considered at high enough forcing frequencies.

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