Experimental Investigations of the evolution of a Wake Vortex System Produced by an Aircraft Model in Proximity of a Plane Ground with Irregularities

Abstract

The dynamics and decay of a wake vortex system in close ground proximity is investigated in a tow tank facility. An F13 model consisting of a singular rectangular main wing is used to generate vortices at a circulation based Reynolds number of 59,212. The current setup permits measurements into the mid-wake region at a range of heights above the ground plane. Flow visualization with dye trails is performed to qualitatively assess regions of 3-dimensionality and propagation of vortex breakdown. Stereoscopic-PIV in a cross-plane is performed firstly with a smooth ground plane then with irregularities with differing profiles. Analysis of the spatial-temporal evolution of vortex trajectories and circulation is performed along with assessment of boundary layer development and formation of secondary vorticity. The results of the various configurations are compared both qualitatively and quantitatively with each other and to computational fluid dynamics simulations. Investigations revealed that initiation of vortex breakdown occurs within close proximity of the ground irregularity and propagates both upstream and downstream and is highly 3-dimensional. Interaction of this breakdown with the primary vortex was seen to be beneficial in reducing its severity but does not result in complete destruction.