Date of Award

Spring 5-17-2017

Author's Department

Mechanical Engineering & Materials Science

Degree Name

Master of Science (MS)

Degree Type



High lift devices used in transport aircraft are complex multi-element wings with slats and flaps which are difficult to design and they incur high manufacturing and maintenance costs. Taking all requirements into consideration, for light aircrafts using Gurney Flap may offer a low cost, low maintenance solution for improving the aerodynamic performance of aircraft during take-off and landing. Gurney Flap, first invented by Dan Gurney, is a small tab projecting from the trailing edge of airfoil. Gurney Flap can increase the lift coefficient and decrease the angle of attack for zero lift. However, at low angle of attack, Gurney flap also increases the drag coefficient. Overall, a net benefit in the lift-to-drag ratio can be provided by Gurney Flap since it increases the pressure on the lower surface of the airfoil upstream of the Gurney Flap. For generating the same lift force, less suction on the upper surface is needed with Gurney Flap. The effect of ground on a clean airfoil at moderate angles of attack is to increase the lift force and decrease the aerodynamic drag. The obstruction due to the ground increases the pressure on the lower surface of the wing and weakens the trailing vortices form the wing. This effect of ground on the airfoil aerodynamics has been demonstrated experimentally and computationally by many investigators. While the ground effect of a single airfoil and a multi-element airfoil has been studied for decades, few studies have been conducted on the ground effect due to a Gurney Flap. The goal of this thesis is to perform numerical simulations of flow over an airfoil/wing with a Gurney flap in ground effect and analyze its aerodynamic performance and flow physics.


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