Investigating the ground effect on aerodynamic characteristics of airfoil in oscillatory flow

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Abstract

When a wing is placed near a wall surface, two phenomenons occur. The lift force is increased and the drag force is reduced which will finally lead to high lift to drag ratio. This phenomenon is known as the effect of surface or ground effect. In this study, a two dimensional simulation has been developed to investigate the effect of oscillatory flow around a NACA 4412 airfoil near a wall surface. The effect of wing distance from the surface, the amplitude and frequency of the oscillating flow have been analyzed on the aerodynamic coefficients. The lift coefficient is increased due to the air compression and trapping between the underside of wing and the wall. The drag coefficient is reduced because of wall jet at the trailing edge which increases the back pressure. According to the results obtained in the unsteady case, by reducing the amplitude of free-stream velocity, the lift coefficient is enhanced and the drag coefficient is reduced. Also the drag coefficient decreases due to increasing frequency of the oscillating flow.

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References

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Journal of Solid and Fluid Mechanics
Volume 5, Issue 3 - Serial Number 3
September and October 2015
Pages 185-196

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