Experimental investigation of twin-fin buffeting and suppression

Abstract

An investigation has been undertaken to study the characteristics of vertical fin buffeting for various twin-fin configurations at high angles of attack. Tests were performed in the 2.1 X 1.5 m low-speed wind tunnel at the University of Bath, using three 60-deg cropped generic delta wings of 0.5-m span. To sense unsteady pressures at the fin surface, a rigid fin instrumented with miniature pressure transducers was fabricated, whereas a flexible fin of similar planform and size was used to measure the buffeting response. It was found that the fin configurations were typified by two maximum buffeting conditions. The first peak response was effectively a vortex/fin interaction in isolation, whereas the second peak response was the result of a vortex shear-layer oscillation between the fins. A novel flow concept (tangential leadingedge blowing) was then used to decrease the levels of buffeting response for all fin configurations. By reducing the effective angle of attack of the vortical flow, peak buffeting responses were shifted to higher angles of attack.