Numerical investigation of the aerodynamics of a delta wing in ground effect

The aerodynamics of a delta-wing aircraft is influenced by the ground effect during takeoff and landing. In this paper, the ground effect of a sharp leading-edge delta wing with sweep angle of 65 deg is investigated by using ANSYS Fluent employing the unsteady compressible Reynolds-averaged Navier-Stokes equations and the shear-stress transport k-ω turbulence model. The angle of attack is fixed at 20 deg and the flight height is varied from high altitude to close proximity to the ground. The lift, drag, and nose-down moment increase with decreasing flight height, and the major contribution to the variation in aerodynamic forces comes from the windward side of the wing. In ground effect, the pressure under the delta wing increases due to the "ramping" effect, the strength of the leading-edge vortex enhances before breakdown, and the vortex breakdown is promoted due to the increased adverse pressure gradient.