A PREDICTION MODEL FOR ADVANCED LEADING-EDGE VORTEX FLOW CONTROL

THE OBJECTIVE IS TO DEVELOP A TOOL FOR DESIGNING VORTEX FLAPS ON ADVANCED FIGHTER AIRCRAFT INCLUDING THE EFFECTS OF VISCOSITY. ANALYTICAL METHODS, INC. PROPOSES TO USE AN UNSTEADY TIME-STEPPING VERSION OF ITS SURFACE SINGULARITY PANEL METHOD, VSAERO, AS A BASIS FOR THIS WORK. THIS WILL GENERATE THE PRELIMINARY VORTEX STRUCTURE (LEADING-EDGE VORTICE, FOREBODY VORTICES, ETC.) FOR THE COMPLETE CONFIGURATION; THE SOLUTION WILL BE COMPUTED AS A LIMITING STATE AT CONSTANT INCIDENCE WITHOUT CONICAL FLOW OR SLENDER BODY ASSUMPTIONS. COUPLED BOUNDARY LAYER CALCULATIONS--PROCEEDING AWAY FROM PREDICTED ATTACHMENT LINES--WILL PROVIDE DISPLACEMENT EFFECTS AND SEPARATION LOCATIONS. THE LATTER WILL INDICATE WHERE NEW WAKE SHEETS (E.G., SECONDARY VORTICES) NEED TO BE ADDED BEFORE COMPUTING THE NEW PRESSURE DISTRIBUTION FOR THE NEXT CYCLE. EXISTING EXPERIMENTAL DATA WILL BE USED FOR CORRELATION PURPOSES AND TO HELP REFINE MODELING DETAIL. IN DEVELOPING THIS APPROACH INTO A PRACTICAL DESIGN TOOL, THE AIM WILL BE TO MAINTAIN THE ARBITRARY GEOMETRY CAPABILITY, THE LOW COMPUTING COST AND THE EASE OF USE OF THE PANEL METHOD AND TO MODEL THE EFFECTS OF VISCOSITY AS CLOSELY AS POSSIBLE.