Aerodynamics of an oscillating wing in ground effect

• Main Author: Molina, Juan
• Published: University of Southampton 2011
• Subjects: 629.1323
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582653

This research intends to provide new insight into the aerodynamics of wings in ground effect under dynamic motion. This work represents a new step forward in the field of race car aerodynamics, in which steady aerodynamics are well understood. As the first comprehensive study on oscillating wings in ground effect, several modes of oscillation were studied numerically, including heaving, pitching and combined motion of an airfoil and heaving of a wing fitted with endplates. A wide range of reduced frequencies were tested for the simulations at different ride heights, which showed appreciable differences with respect to a stationary wing. The flowfield around the airfoil was obtained by solving the Reynolds-Averaged Navier- Stokes equations, while Detached Eddy Simulation was used for the wing. A dynamic mesh model was implemented to adapt the grid to the wing motion. The results showed other aerodynamic mechanisms in addition to the ground effect, namely the effective incidence and added mass. Stall can be postponed to lower ride heights by increasing the frequency of heaving, while a pitching airfoil can stall below the static stall incidence when placed close to the ground. A stability analysis showed that flutter can occur at low frequencies in heaving motion but increasing the frequency always stabilises the motion. The behaviour of the vortex formed on the inboard face of the endplate is altered by the heaving motion and has an important effect on the downforce generation. Vortex breakdown can be induced or suppressed depending on the frequency and effective incidence. At high frequencies, these vortices interact with counter-rotating trailing edge vortices to form vortex loops that transform into omega vortices in the wake. Additional experiments for a stationary wing serve to qualitatively validate and complement the reference cases.