A Numerical Study on the Hysteresis Effects of a Low Subsonic Wing Fitted with Vortex Generators

This study investigates the hysteresis phenomenon of a subsonic wing during pitch-up and pitch-down maneuvers using a numerical method. The wing, based on the NACA63415 airfoil, features slight tapering and dihedral that were typical characteristics of subsonic aircraft. The analysis includes surface pressure contours, Cp distributions, Q-criterion iso-surfaces, and streamlines for understanding the flow behaviors. Results show that during the pitch-up phase, the stall angle was 22° that was 4° higher than the static stall angle. In contrast, the pitch-down phase revealed a recovery angle of 12°, indicating a prolonged recovery process. Vortex generators improved performance during the pitch-up phase but had little effect during pitch-down phase. These findings provide valuable insights into the hysteresis behaviors of the subsonic wing and could offer useful information for the design of future low-subsonic aircrafts.