Prediction of Post-Stall Flows on Airfoils

Abstract

The calculation of the performance of airfoils requires the solution of the conservation equations, which, in general, can be accomplished in different ways. An important approach, where large scale computational facilities are available, is to solve the Reynolds-averaged Navier-Stokes equations or a reduced form such as the so-called parabolized and thin-layer Navier-Stokes equations. Two alternative and successful computational methods have been proposed by Maskew and Dvorak [126] and Gilmer and Bristow [79] in which an empirical inviscid flow model is used to represent the effects of flow separation with solutions of the boundary-layer equations in standard form up to the point of separation and a free surface assumption to model the separated flow region. The shape and the length of the separation are computed by satisfying a constant pressure boundary condition on the surface, and very good results have been obtained for airfoils over a wide range of angles of attack including stall and post-stall.

This research was conducted under the Independent Research and Development Program of the McDonnell Douglas Corporation