Method for calculating the unsteady flow of an elliptical circulation-control airfoil

A numerical method is developed to study the unsteady aerodynamics of an elliptical airfoil in two-dimensional incompressible flow. In this method, it is assumed that the separation positions of the wall jet on the upper surface and the boundary layer on the lower surface of the airfoil can be determined by solving the quasisteady boundary-layer equations; the discrete vortex model is used to model the wake, and the potential flow is calculated by conformal mapping technique. Results are presented and discussed for a number of cases that illustrate relevant characteristics of the unsteady flow of circulation-control airfoils.