An Experimental Investigation of the Effects of Body Surface Suction on the Wing-Body Junction Vortex
PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
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Various techniques of reducing the effect of the wing-body junction vortex were studied and two approaches were implemented experimentally. The results of previous studies using the passive approach of reducing the wing leading edge radius were successfully reproduced. The active method of body surface suction to remove the approaching body boundary layer was also investigated. The elimination of this boundary layer was intended to remove the source of vorticity from which the vortex develops. The ideal or minimum suction flow rate required to totally remove the boundary layer and suppress the vortex was equal to the flow rate through the boundary layer. Mean velocity data were acquired via five-hole probe surveys at a freestream approach velocity of 7.4 m s. The velocity data were differentiated to yield mean vorticity contours and net circulation values these results gave measures of the vortex strength. It was clearly shown that this active technique of body surface suction was capable of suppressing the large scale vortex more completely than known passive techniques. For the rectangular suction hole used, a suction volumetric flow rate of nearly twice the actual boundary layer volumetric flow rate was required to totally eliminate the vortex structure. This greater than ideal suction flow rate and the observed introduction of vorticity at the suction hole edges implied the need for future studies to investigate more efficient designs.