Aerodynamic Loads on Simultaneously Pitching and Rotating Flat Plate: Effect of Pitch Rate and Pivot Location*

The flow over a rotating and pitching wing is unsteady, three-dimensional, and a simplification of insect wing motion. The design of bio-mimicking micro air vehicles is inspired by this motion, which sparks interest in studying flow structures along a simultaneously pitching and rotating flat plate. The influence of wing pitch rate and pitch pivot location on aerodynamic performance of rotating wings has not yet been fully investigated. To this end, the present investigation utilizes a flat plate (aspect ratio = 6), rotating at a Re of 20000, and pitch angle ranging from 0 – 90°. Two parameters are considered in this poster: the non-dimensional pitch axis (x_p/c = 0, 0.25, 0.50, 0.75, 1) and the reduced pitch rate (0.03 ≤ K ≤ 0.3); which is the ratio of pitch velocity to translational velocity (K = α^'c/ 2U_tip). Qualitative flow visualization was conducted via fluorescent dye at the radius of gyration of flat plate. Wing loads were measured using a multi-axis strain gauge load cell. The preliminary results show a generalization in scaling of lift and drag with reduced pitch rate and pivot point and relate such scaling to the formation, growth, and pinch-off of leading-edge vortices.