Stall in ground effect using the unsteady vortex lattice method with Kirchhoff-based correction

Abstract

The goal of this research is to evaluate the stall behavior of a high aspect ratio rectangular wing in ground effect using an unsteady vortex-lattice method with a Kirchhoff-based correction (UVLM-K), including how the lift coefficient achieved in stall is affected by dynamic ground effect. A flow separation algorithm based on the Kirchhoff-Helmholtz theory and a flow separation model presented by Fischenberg are applied. The code was validated using experimental data from previously published works. The stall behavior of a rectangular wing of aspect ratio of 8.587 formed with a NACA 4415 airfoil section was studied in static and dynamic ground effect. To obtain the empirical data required by the UVLM-K, the NACA4415 airfoil was simulated at fixed height aboveground using a finite-volume code solver. The wing simulation results have shown that the lift coefficient achieved by the wing in stall for takeoff and flare maneuvers are lower than those estimated at a fixed height above the ground. It can be concluded, based on the results obtained herein, that the stall behavior of a wing in dynamic ground effect depends on the history of the maneuver.