Ground-Effect Aerodynamics of a Nonslender Delta Wing with Bio-Inspired Leading-Edge Modifications

This study experimentally investigates the flow physics and ground-effect aerodynamics of a nonslender delta wing with bio-inspired leading-edge modifications. A base wing configuration with a 45-deg sweep angle is compared with sinusoidal and saw-tooth leading-edge configurations in a low-speed wind tunnel using force and near-surface particle image velocimetry (PIV) measurements. Experiments were conducted over a wide angle of attack range and at multiple ground clearances to investigate the influence of the bio-inspired modifications and the static ground effect. Near-surface PIV measurements showed that the sinusoidal wing model primarily alters the leading-edge vortex structure, while the saw-tooth wing model generates multiple small-scale vortices that energize the shear layer. The flow physics of modified wings show delayed large-scale three-dimensional flow separation, resulting in more spatially distributed turbulent kinetic energy and Reynolds stress regions compared to the base wing. Force measurements show that modified wings achieve higher maximum lift coefficients and smoother post-stall characteristics than the base wing model. In ground effect, decreasing ground clearance collectively increases both lift and drag coefficients for all configurations, while the stall angle remains unchanged.