A method for computing the three—dimensional flow about wings with leading—edge vortex separation Part II: Description of computer program VORSEP

Abstract

In part I of this report a method is described for computing the incompressible flow about slender, thin wings with leading-edge vortex separation. It is assumed that both the wing and the flow field are symmetric with respect to the x—z plane. The method can handle delta—like wings of quite general planform and shape. However, in the formulation it is assumed that the wing is pointed, that the vortex sheet is attached all along the leading (and side) edge and joins the wake of the wing in a smoothly manner at the trailing edge. The wing, leading—edge vortex sheet and wake are represented by a doublet distribution. For the rolled-up portion of the leading edge sheet, i.e. the leading—edge vortex, the concentrated vortex/feeding sheet mode is employed. In the method the portion of the wake near the trailing edge is relaxed fully. A second—order accurate panel method is employed to compute the velocity field induced by the doublet distribution. The unknown parameters in the panelwise representations for the geometry and the doublet distribution are found by solving the system of nonlinear equations, resulting from applications of the boundary conditions, employing a quasi—Newton iterative procedure. Upon convergence of the iterative procedure the pressure distribution is computed and integrated numerically to obtain the forces and moments of the wing. This part of the report describes the computer program developed, designated VORSEP, in some detail.