Surface vorticity modeling of flow around airfoils

Abstract

A surface vorticity method based on the new Kutta condition has been developed for solving the steadȳ ow around an airfoil and unsteady separated¯ow past airfoil with a spoiler. In a discussion of the Kutta condition, it is argued that the appropriate Kutta condition is required to obtain a satisfactory solution. In this paper, two new methods of satisfying the Kutta condition incorporated in the surface vorticity method are described. The ®rst method, which is based on results from¯ow visualization, is to introduce an additional control point at a short distance downstream of the trailing edge. In order to account for the fact that the velocity above the trailing edge is different from that below as in the real¯ow, the second method is to add a ®nite segment of vortex sheet downstream of the trailing edge. The present Kutta conditions are incorporated into the surface vorticity method and extend to solve unsteady¯ow around an airfoil with a spoiler. The computational results are in reasonable agreement with other computation as well as experiments.

A vortex method for separated flow around an airfoil with a detached spoiler

“…When a spoiler is rapidly erected, experimental studies carried out by Consigny et al (1984) showed that a period of initial increase in lift is induced on the wing before the longterm reduction is reached. Some computational studies of ow involving spoilers have been reported by Tou and Hancock (1987), Bearman et al (1989) and Yeung (1996 and1998) with all these cases considering the conventional type of spoiler, i.e. no venting at its base.…”

“…At each time step, the velocity ®eld is made up of the induced velocity from each point vortex and the body concerned. Extensive investigations in the ®eld of aerodynamics based on the vortex method have been reported by, for example, Basu and Hancock (1978), Hsu and Wu (1988), Graziani et al (1995), Yeung (1996 and1998), and Casciola and Piva (1998). Sarpkaya (1989) made a comprehensive review about the vortex method.…”