Structure and Control of Three-Dimensional Unsteady Flow in Delta Wings at HighAngle-of-Attack

摘要

This program has focused on the instantaneous flow structure generated bycontrolled motion of wings in the pitching and rolling modes, as well as application of local control techniques for mediating the flow structure. The instantaneous flow structure is characterized using high-image-density particle image velocimetry, in conjunction with new types of two and three dimensional imaging techniques. This approach provides instantaneous velocity fields, streamline patterns and vorticity distributions at crucial locations in the flow field and allows a proper basis for eventual control of the flow structure. Characterization of the flow structure in the rolling mode of wing motion has involved definition of the critical states of the flow, based on the static locations of onset of vortex breakdown. The instantaneous crossflow and streamwise topology has been defined as a function of row angle. For pitching motion of the wing, simultaneous maneuver of the wing and application of control in the form of deflection of a leading-edge flap and blowing from the trailing-edge provide an effective, interactive means of altering the onset of vortex breakdown, thereby enhancing the effectiveness of maneuvers at high angle of attack.