Multifidelity Aerodynamic Optimization of a Helicopter Rotor Blade

Abstract

A multifidelity optimization technique is applied to the design of a helicopter rotor blade to improve its performance in forward flight. This optimization technique is based on a surrogate model that replaces the high-fidelity computational fluid dynamics (CFD)/computational structural dynamics (CSD) simulations necessary to capture the three-dimensional unsteady effects generated in the flowfield of a complex blade geometry. The single low-fidelity model based on kriging methodology and generated by lifting-line simulations leads to a power benefit of 2.5%, which is not reproducible by an a posteriori high-fidelity CSD/CFD computation. The optimization procedure using cokriging surrogate models based on two levels of fidelity (lifting-line and CSD/CFD simulations) leads to a realistic blade planform, for which the power benefit is estimated at 2.2%. This optimized solution, obtained after a factor-of-six reduction in CPU time, shows the advantages of using a cokriging surrogate model (rather than a single-fidelity kriging model) for aerodynamic optimizations.