Using shock control bump to improve transonic buffet boundary of airfoil

Airfoil buffet boundary is an important aerodynamic parameter which is second only to the lift-drag ratio. By using various steady aerodynamic parameters of the lift curve, the trailing edge pressure deviation and reversal in shock movement as the basic criteria, the buffet boundary of transonic airfoil RAE2822 in the specified flow conditions can be determined by solving steady Reynolds-averaged Navier-Stokes equations. A specific shape and position of the shock control bump is designed for airfoil RAE2822 by testing many computational fluid dynamics (CFD) solutions. The study finds that the shock control bump can significantly reduce the shock strength near the buffet onset angle, stabilize shock position and deter the occurrence of buffet, thereby achieving the purpose of expanding the buffet boundary. The buffet onset lift coefficient in the transonic flow conditions can be increased by 5%-10%. When the angle of attack is small or when it is larger than the buffet onset angle, the shock control bump has little effect on the dynamics of the airfoil.