Computation of F/A-18 tail buffet

The aerodynamic loads that cause tail buffet on the F/A-18 fighter aircraft were analyzed using computational fluid dynamics (CFD). The half-body aircraft geometry was modeled using an overset grid system, which included the fuselage, wing, wing leading-edge extension (LEX), deflected wing leading-edge flap, inlet geometry, and vertical and horizontal tails, Time-accurate solutions with and without the LEX fence were obtained at an high-angle-of-attack flight condition, Time histories of the surface pressures on the rigid vertical tail were computed, The vertical tail root bending moment and side force time histories were obtained from the surface pressure distributions, Power spectral density analysis of the time histories were computed, Results were compared with experimental data from subscale and full-scale wind-tunnel tests, The current grid system yielded results that agree quite well with experimental data, The CFD solution predicted the unsteady rms pressure coefficient, the peak power, and the favorable effect of the LEX fence on these quantities. These results indicated that current CFD methods can be used to predict tail buffet and can be a useful tool for analyzing similar problems in aircraft design.