Experiments on a 60-Degree Delta Wing with Rounded Leading-Edge Vortex Flaps

Abstract

Low-speed wind-tunnel measurements were done on a 1.15-m span 60-deg delta wing with rounded leading-edge vortex flaps. The purpose of the measurements is to assess the benefits of the rounded leading-edge vortex flaps in regard to improving the lift/drag ratio of delta wings. Force and surface pressure measurements were made at a Reynolds number based on a centerline chord of 2 x 10 6 . The increase in the radius of the rounded leading edge reduces the drag significantly both with and without flap deflection except in the minimum drag region. Deflecting the rounded leading-edge vortex flap improves the lift/drag ratio at relatively higher lift coefficients, when compared with the sharp-edged vortex flap. The largest improvement in the lift/drag ratio as compared with the sharp-edged delta wing with vortex flaps is more than 25% in the lift coefficient range between about 0.6 and 0.8 for the rounded-edge delta wing with flaps that were deflected 30 deg downward