Effect of airfoil distance to water surface on static stall

Abstract

In this study, viscous, turbulent, and steady flow around an airfoil near the water surface has been simulated through a numerical method. In this simulation, Navier-Stokes equations have been solved using the finite volume method with a discretized second-order accuracy and PIMPLE algorithm. The Volume of Fraction (VOF) method has been employed to predict the free surface flow. A part of the simulation results has been validated through numerical and experimental data. Besides considering the style of flow separation in the angles of numerous attacks and airfoil static stall near the surface of the water. For this purpose, the airfoil simulation has been processed airfoil in the 68,000 Reynolds number, angle of attack of 2.5 to 11 degree and different distances from the water surface ( h/c = 0.5, 1, ). In a larger angle of attacks, flow is initially separated from the leading edge of the surface, and then it attaches to the surface at a lower point. This reattachment leads to an increase in adverse pressure gradient and the formation of a larger separation in the downstream of the airfoil. The pressure gradient dramatically increases, and the flow gets separated from the upstream of the airfoil. Upon lowering distance from the surface, static stall takes place at a higher point and a lower angle of attack, respectively.

Ground effect on the aerodynamics of a flapping wing in forward flight: an experimental study

“…The reduction of distance caused the air to be trapped between the surface under the flapping wing and the floor of the test section. The pressure increased on the lower surface of the flapping wing, and then the pressure difference of the top and bottom surfaces of the wing increased (Azargoon et al, 2019(Azargoon et al, , 2020Esmaeilifar et al, 2017) causing a rise in the lift production. The spread of vortices was prevented for the wing underground effect, which was another reason for lift augmentation.…”

“…The ground effect has been addressed by many researchers because of its benefits to aerodynamics performance. Many numerical and experimental studies investigated the flight of wings underground effect (Rayner, 1991;Barber, 2006;Esmaeli et al, 2010;Djavareshkian et al, 2011;Azargoon et al, 2019Azargoon et al, , 2020Azargoon and Djavareshkian, 2021;Esmaeilifar et al, 2017). The results of studies showed that the aerodynamic performance and the performance indices of flapping wings improved by flying near the surface (e.g.…”

Stall Behavior Curved Planform Wing Analysis with Low Reynolds Number on Aerodynamic Performances of Wing Airfoil Eppler 562

“…Separation can also occur in the wing root area where there is a junction between the wing and the fuselage wall surface. The separation in this area is caused by the angle of attack and the geometry between the wing and fuselage [2,3].…”