Discrete Adjoint Design Optimization Approach for Increasing Transonic Buffet Onset Angle-of-Attack

Abstract

Presented is a discrete adjoint method for transonic buffet design optimization. The method is based on a frequency domain approach for modeling unsteady aerodynamics. Automatic differentiation is used to derive the computer code representing the adjoint gradient unsteady frequency domain solver. The gradient information is then used to optimize the geometric design in order to minimize unsteady aerodynamic response near the buffet onset boundary. The methodology is demonstrated for a NACA 0012 airfoil transonic buffet configuration. Preliminary analysis indicates that design modification can be done to increase buffet onset angle-of-attack by around one degree for a flow condition where the buffet onset angle-of-attack for the nominal design is roughly three degrees, and that it is possible to do this while maintaining the symmetry of airfoil as well as not greatly altering the maximum airfoil thickness.