Influence of Pitching Axis Location on Aerodynamics of Asynchronous Pitching and Decelerating Wings

The study investigates the effect of pitch-axis location Xp on the aerodynamic performance of a wing undergoing pitching-deceleration motion. The deceleration duration is held constant, while the pitching motion is varied at dimensionless pitch durations β = 0.20, 0.40, and 0.80, corresponding to reduced pitch rates of K = 0.40, 0.20, and 0.10, respectively. Since the pitching motion completes in advance of the deceleration phase ending, the maneuver is therefore classified as asynchronous. The findings show that the two distinct lift peaks observed for a pitching wing in uniform flow occur only for a decelerating wing at K = 0.40. Increasing Xp reduces the peak lift magnitude without altering peak location, whereas increasing K amplifies the peak lift and modifies its location within the motion cycle. Wing efficiency analysis shows that decreasing K yields enhanced aerodynamic efficiency, and that positioning Xp closer to the trailing edge provides additional performance benefits when combined with an appropriate K. These findings suggest that pitch-axis positions aft of the quarter-chord are advantageous for energy-harvesting applications.