Aerodynamic Design of Helicopter Rotor Blade in Forward Flight using Response Surface Methodology

This paper describes an efficient and robust optimization method for the helicopter rotor blade design in forward flight. To achieve the goal, the effect of modifications in airfoil and blade geometry on the rotor performance is investigated. Navier-Stokes analysis is employed to compute the dynamic response of an airfoil, which simulates the unsteady flow-field of the rotor in forward flight. Free-wake panel method is used for the rotor blade design study. The optimization system consists of two categories; Response Surface Methodology (RSM) to construct the response surface model based on the D-optimal 3-level factorial design and Genetic Algorithm (GA) to obtain the optimum solution of a defined objective function with penalty terms of constraints. The influence of design variables and their interactions on the rotor aerodynamic performance is examined through the optimization process. The application of this optimization method results in the increase of the airfoil lift-to-drag (C1/Cd) ratio and the rotor blade performance (CT/CQ).