Progress in observational studies of aircraft wake vortex in ground proximity

Observational experiment of aircraft wake vortex is the basis of studying the evolution behavior of aircraft wake vortex. Disturbed by the effects of atmospheric environment, the exact observation of aircraft wake vortex in cruising and approaching is challenging. In this paper, the laboratory wake observation method including the wind tunnel and towing tank experiment, and the in-site observation method using laser radar and microwave radar equipment has been discussed. The wind tunnel experiment is able to capture the roll-up, development, fall out of the aircraft wake vortex as well as vortices merging (including merging among the wing tip vortex, flap vortex, horizontal tailplane vortex, jet-flow, etc.), while the towing tank experiment can well capture the evolution behavior of aircraft wake vortex in the extended near field and mid field. In addition, the in-situ observational experiment can well capture the process of evolutionary dissipation of aircraft wake vortices in the atmospheric environment, so it can be served as an important reference for studying the effect of different atmospheric environment on the evolution process of aircraft wake vortices, and further for establishing the dynamic separation standard of aircraft wake vortex.