Prediction of Buffet Loads on Twin Vertical Tails Using a Vortex Method

摘要

The work is concerned with the computation of F/A-18 vertical tail buffet due to LEX vortex burst using vortex methods of unsteady flow modelling. It is recognized that prediction of buffet loading requires accurate modelling of the unsteady pressure field past a burst LEX vortex. To reduce computational overheads associated with simulation of flow over the complete aircraft, a more generic delta-wing, twin vertical-tail configuration was used for initial studies. The aim is to generate an unsteady, vortex-breakdown flow using a delta wing and to place a vertical tail, which is cantilevered, downstream of the vortex breakdown flow. The paper describes the development of an unsteady vortex model for prediction of buffet loads and its validation against experimental data. Results of computation indicate that the vortex model is able to predict the onset of leading edge vortex breakdown and qualitatively describe the characteristics of unsteady buffet pressures arising on the rigid tail.