A Flow Visualisation Study to Tip Vortex Formation,

The process by which a wing or rotor blade tip vortex is generated has been studied in a water tunnel using dye and hydrogen bubble flow visualisation techniques. In particular, the effects of the shape of the lateral tip edge on vortex formation have been examined. Three edges shapes were tested-a square tip, a square tip with rounded fairing, and a square tip with bevelled fairing. The square tip was found to have the most complicated vortex system, with vortices forming on the tip edge face as well as above the wing. The observed flow features ere generally similar to those proposed in the literature on the basis of pressure measurements, velocity measurements, and surface flow visualization in wind tunnels and on whirl towers. The vortex systems for the rounded and bevelled tips were less complicated. The shape of the tip edge has a significant effect on the structure of the tip vortex system, and may thus influence the tip loading characteristics. Verification of this will require further testing. Author