Decay and Modification of Trailing Vortex

Some experiments of decay and modification of a trailing vortex, which is shed from the tip of a lifting wing are described. Flow fields of the trailing vortex are shown and the effects of the air jet injection from the wing-tip on the attenuation of the disturbances caused by the trailing vortex are discussed. When the air jet is not injected, changes in the flow fields near the trailing vortex in the flow direction are quite small and the total circulation and the disturbances due to the trailing vortex such as the large circumferential velocity, defects in the axial velocity and the static pressure are maintained in the region far downstream of the wing. When the air jet is injected, vortex filaments are distributed over a wide region and the disturbances can be suppressed to small quantities. The turbulence caused by the trailing vortex increases with the distance from the wing when the air jet is not used, but the jet injection has an effect to attenuate the turbulence.