Wind Tunnel Test of Gurney Flaps and T-Strips on an NACA 23012 Wing

Abstract

A wind tunnel test was carried out on an aspect ratio 6 wing equipped with Gurney flaps and trailing edge T-strips. The test was conducted at the University of Washington Aeronautical Laboratory’s 8 x 12 foot low-speed wind tunnel at Reynolds numbers of 1.95x10, 1.02x10 and 0.51x10. The NACA 23012 test wing was unswept and untwisted with a 90 inch span and a constant chord of 15 inches. Gurney flap heights of 0.21%, 0.52%, 1.04%, 1.46%, 2.08%, 3.33%, 4.00% & 5.00% chord were tested on the model. T-strip heights of 0.42%, 1.04%, 1.67%, 2.08%, 2.92%, 4.17% & 5.00% chord were also tested. Results showed that Gurney flaps produced a positive increment in lift coefficient, a negative shift in the zero-lift angle of attack, and an increase in the wing maximum lift coefficient. Tstrips produced an increase in the slope of the lift curve and an increase in maximum lift coefficient, but produced no shift in the wing zero-lift angle of attack. Gurney flaps produced a negative (nose-down) shift in the pitching moment curve and a rearward shift in the wing aerodynamic center. T-strips also produced a rearward shift in the wing aerodynamic center, but produced no increment in the pitching moment coefficient near zero lift. Both devices produced a drag increment that was non-linear with device height, larger Gurney flaps and T-strips producing a disproportionately larger drag increment.