Application of a semi-empirical method to model subsonic vortex lift over sharp leading-edge delta wings

A semi-empirical method is applied as a complement to the FlightStream solver, to more accurately model subsonic vortex lift over a sharp leading-edge delta wing. The method, based on the prediction of flow patterns and the application of the Polhamus method, is particularly well-adapted to a preliminary aerodynamic design phase. Within a few minutes, it can accurately predict the aerodynamic forces generated by the flow over a delta wing, which are strongly affected by the presence of a leading-edge vortex. This study presents a detailed analysis where computed results are compared against experimental data. Those were obtained from a test case of a 65° subsonic delta wing experiment (case 1), along with a sensitivity analysis against sweep angle and aspect ratio where multiple subsonic delta wings were tested (case 2). A good agreement is observed between computed data and experimental results, within pre-stall, before the vortex bursts. Analysed results demonstrate the validity of the method, for multiple wing configurations associated with different flow conditions.