Origin and Control of the Flow Structure on Unmanned Combat Air Vehicle

Flow structure on delta wings having low sweep angle, representative of those used in UCAVs and MAVs, is characterized in detail using technique of quantitative imaging, high-image-density particle image velocimetry. Cases of stationary wings, wings subjected to control at their trailing-edges, and wings undergoing prescribed pitching maneuvers have been addressed as part of this investigation. The sweep angle of each wing is sufficiently small, such that the patterns of the flow structure exhibit elongated separation layers in the crossflow plane. These patterns can be interpreted in conjunction with patterns of streamline topology in the cross flow plane, as well as patterns of root-mean-square velocity fluctuation and velocity spectra, in order to provide insight into the origin of unsteady loading of the aerodynamic surface. As an adjunct to the series of investigations of flow past delta wings in absence of a tail, the interaction of vortex breakdown with the simulated tail of awing has been characterized using quantitative imaging and evaluated using a technique of proper orthogonal decomposition POD.