Three-Dimensional Unsteady Flow Fields Elicited by a Pitching Forward Swept Wing

The three-dimensional flow field about a forward swept, NACA 0015 wing was studied using multiple exposure, phase-locked flow visualization viewed from orthogonal perspectives. The wing was oscillated sinusoidally in pitch while stroboscopic photography was used to record the pitching-dependent alterations in flow field structure. Flow interactions were visualized in discrete fashion for a variety of spanwise views, using different k values and mean angles of attack. The major flow field characteristics were the tip and the leading edge vortices. The strong helical tip flow vortices dominate most of the observed flow structures near the wing tip across all test conditions. The far inboard span locations were dominated by interaction of the flow structures were quite different than the qualitative predictions of previous research. The spatial domain of the flows was quite pronounced and seemed to be specific to the wing geometry of the test configuration. EDC