Flow Visualization of Cavity Effects on Separation and Flow Structure Over Riso Airfoil

Wind energy is one of the clean energies from which energy can be generated via devices such as wind turbines. In wind tttrbine, Airfoil profile is one of the most important parameters in its efficiency. Therefore, investigating aerodynamic characteristics of wind turbine airfoil such as flow separation and its location, is a significant subject. In Fact, by delaying separation position, it is possible to increase lift force. One of the methods in fluid flow control science for postponing separation is by using a cavity. In this paper a research with subsonic wind tunnel, flow visualization with smoke and photography with the help of laser is done. and flow separation in two different RISO airfoils. one with a cavity at the upper surface of airfoil and the other one without cavity, at angles ofattack of5, 7, 9, 1 1, I3 and 14 degrees was carried out. After performing experiments and inspecting photos, it was found that at suitable angles of attack, the cavity can delay flow separation due to the formation of small oscillating flows and its effect onpressure field. and therefore the cavity can increase aerodynamic performance of airfoil.

Keywords:

Riso airfoil , Fluid Flow Control , Wind Tunnel , Flow Visualization , Cavity