with various parameters of the GF being systematically investigated. RANS investigations have been carried out recently by Date and Turnock, Lee and Kroo, Tongchitpakdee et al. , and Jeffrey, who used panel methods to model sections fitted with GFs, reported disappointing results following comparison with experimental data. The earlier numerical investigations by Fripp and Hopkins, Myose et al. Hysteresis effect is observed by Brown and Filippone, when the flow reattachment takes place at lower AoA when incidence is decreased from poststall angles. Saturation in lift for larger GFs is also suggested by Hage et al. Nonlinear relation in lift increment and GF height was also noticed, where lift increased for small GFs rapidly while rate was slower for big flaps. Their analysis also shows that the optimum height of GFs is always below the boundary layer thickness at the trailing edge. for NACA 0012 airfoil.īrown and Filippone conducted experiments at Reynolds number ranging from Re = 42000 to 1.6 × 10 5. Experiments on GF for GU25-5(11)-8 airfoil by Galbraith concluded that GF should be mounted at distance % to prevent major performance degradation as verified by Li et al. Neuhart and Pendergraft visualized recirculation zones behind GF in their water tunnel experiments and also recommended to keep the GF height less than 2% of the chord length to reduce drag penalty which was also verified by Myose et al. have verified the lift enhancement of GF in their experiments. An excellent review of GF research for aircraft wings and other aerodynamics applications was presented by Wang et al. The Gurney flaps are extensively used on helicopters such as Apache AH-64, Sikorsky S76, and Eurocopter AS355 and much research is going on for their use in turbomachines. A Gurney flap is easy to analyze and manufacture because of its very simple design. Over the decades, Gurney flap has attracted the attention of engineers and designers by its performance enhancement. Liebeck conducted first wind tunnel experiments on GF.
It was first used by Dan Gurney on the top trailing edge of the rear wing on his race car to provide extra rear-end down force with minimal aerodynamics disturbance. Gurney FlapĪ Gurney flap (GF) is a microtab fitted to the airfoil near the trailing edge on its pressure side as shown in Figure 1. From the computational investigation, it is recommended that Gurney flaps with a height of 1.5% chord be installed perpendicular to chord and as close to the trailing edge as possible to obtain maximum lift enhancement with minimum drag penalty.
In addition static pressure distribution on the airfoil surface and pathlines and turbulence intensities near the trailing edge are present. Computed values of lift and drag coefficients with angle of attack are compared with experimental values and good agreement is found at low angles of attack. Airfoil with GF is analyzed for six different heights from 0.5% to 4% of the chord length, seven positions from 0% to 20% of the chord length from the trailing edge, and seven mounting angles from 30° to 120° with the chord. The present study comprises steady state, two-dimensional computational investigations performed on NACA 0012 airfoil to analyze the effect of Gurney flap (GF) on airfoil aerodynamics using k- ε RNG turbulence model of FLUENT.
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