Experimental investigation on the characteristics of wingtip vortex at low Reynolds number

The characteristics of wingtip vortex mainly consist of the vortex core radius, the mean vorticity and the tangential velocity, etc., and the accurate measurements are essential for controlling the wing-tip vortex. In the present study, 2D particle image velocimetry was used to measure the velocity fields of the cross-section downstream the wake vortices in the water tunnel, and the measurement region covers the near and mid/far field where the wingtip vortex persists. Due to the effect of the unsteady motion on the accuracy of measurements, we adopted re-centered average method to extract the characteristics of the vortex pair from the velocity field, which improves the accuracy of statistical parameters. The results show that the vortex core radius and the peak vorticity increase and decrease with the stream-wise position with power law respectively; the unsteady amplitude decreases with angle of attack, which indicates that the resistance ability of the vortex pair to the disturbance grows with the vortex strength.