Abstract
In the past extensive research has been carried out, to study the effect of Gurney flap (GF) on symmetric and cambered airfoil for its usage in low Reynolds number regime. Use of GF at the trailing edge of the airfoil enhances the lift due to increase in the effective camber of the airfoil, which in turn improves the aerodynamic efficiency i.e. Cl/Cd. In the present study, Eppler 423 airfoil is used to first understand the aerodynamics of such a highly cambered airfoil and later GF of various sizes were added on it to understand the change in flow dynamics achieved by adding the GF and their impact on aerodynamic parameters such as Cl, Cd and Cl/Cd. Eppler 423 being a highly cambered airfoil produces high lift coefficient and smoother stall and by adding the GF of various sizes the performance of Eppler 423 improves tremendously and reason for this enhanced performance and effect of size of GF are presented in this paper. Vortex Generators (VG) generate counter rotating vortices that allow the flow to remain attached even at high angles of attack. Also, effect of adding VG at the leading edge of Eppler 423 aerofoil is presented in this paper. At last, results obtained from combination of VG at leading edge and GF at trailing edge on Eppler 423 aerofoil are discussed at length.
Highlights
The Gurney flap is a small flap, added at the trailing edge of an airfoil or wing at right angle to the pressure surface
Variation of Coefficient of Lift (Cl)/Coefficient of Drag (Cd) with Gurney flap (GF) and Vortex Generators (VG). When both GF and VG were added on the Eppler 423 airfoil, the effect of VG is to increase the drag as it act as an obstruction in the flow at the leading edge causing reduction in Cl/Cd as compared to an airfoil with only GF
As we compare the net impact of adding a GF on a symmetric airfoil is more in comparison to cambered airfoil
Summary
The Gurney flap is a small flap (like tab in aircraft wing trailing edge), added at the trailing edge of an airfoil or wing at right angle to the pressure surface. An experimental study was conducted by Bob Liebeck [2] on a Newman aerofoil He found that the GF with only 1.25% chord length gave high-lift coefficient by increasing lift and reducing drag at the same time. Liebeck found that the flap height should be between 1% C and 2% C to maximize the aerodynamic benefits from this simple high-lift device He concluded that flaps with a height of more than h = 2% C would significantly increase the drag. Giguere et al [3] conducted the study to understand the effects of the mounting location of the Gurney flap on airfoil They found that the increment of lift coefficient had decreased when the GF has shifted forward away from the trailing edge, weakening the lift-enhancing effects of the flap. Firstly behavior of clean Eppler 423 aerofoil is studied than a comparison is made with configuration having GF and VG only followed by configuration having both GF and VG
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
