Numerical investigation of unsteady aerodynamic characteristics of pitching delta wings

A numerical investigation of the structure of the vortical flowfield over a delta wing undergoing a pitch-up motion from 0° to 90° is presented. Three-dimensional Navier-Strokes numerical simulations are carried out to predict the complex leeward-side flowfield characteristics that are dominated by the effect of the breakdown of the leading-edge separation vortices. Two cases are considered to investigate the frequency effect on the flowfield structure and aerodynamic loads for the delta wing. As the frequency increases, the location of vortex breakdown delays, and the lift and drag coefficients increase. For lower frequency case, the location of vortex breakdown attains the wing apex early, and the lateral moments are more evident resulting from the earlier occurrence of the asymmetric flowfield over the delta wing at high angles of attack.