A Novel Optimization Approach of Transonic Buffet for a Supercritical Airfoil

Enough margin from the cruise operating condition to the buffet onset is necessary to provide a margin of maneuverability for aircraft. This paper presents a novel optimization approach of transonic buffet for supercritical airfoils based on the lift curve break method using steady Reynolds-averaged Navier–Stokes simulation to improve optimizing efficiency. Three steady results (two lift coefficients corresponding to the cruise operating conditions with different fuel quantities, and one lift coefficient larger than that of the buffet onset) are fully utilized to explore the potential for improving buffet behavior of the supercritical airfoil while maintaining the aerodynamic performance at cruise operating conditions. The optimization results of a typical supercritical airfoil show that the buffet-onset lift coefficient is increased by 4.1% compared to the original airfoil, and the shock oscillation is significantly reduced at the same lift coefficient. The unsteady Reynolds-averaged Navier–Stokes validation results indicate that the optimized airfoil can increase the time-averaged lift coefficient by 5.6% at the same buffet magnitude as the original airfoil. In conclusion, this novel approach achieves efficient and practical optimization of transonic buffet for supercritical airfoils, which has the potential to improve the design level of modern high-speed aircraft.