An Examination of Aerodynamic and Structural Loads for a Rotor Blade Optimized with Multi-Objective Genetic Algorithm

Abstract

A rotor blade design optimization framework has been developed by integrating the Dakota, C81Gen, ParFoil, and RCAS software packages using Galaxy Simulation Builder (GSB). It provides a fully automated, GUI-based design tool for rotor blade optimization. Global design optimization is successfully carried out by optimizing airfoils on the UH-60A rotor blade using Multi Objective Genetic Algorithm (MOGA) in Dakota. The design optimization objective is to minimize rotor power at µ = 0.3 and in hover. A total of 12 design parameters are used and 50,000 function evaluations are made with MOGA to optimize three airfoil segments ranging from r/R=0.736 to the blade tip. The resulting optimal design shows favorable rotor power reductions over a full range of flight speeds including hover. It shows a 9.2% reduction at µ = 0.4, a 6.7% reduction at µ = 0.35 and a 0.6% reduction in hover. The significant rotor power reductions in high speed cruise result mainly from a drag reduction on the advancing side near the blade tip where it is near the transonic region. This outcome is possible with morphing airfoils by shifting the camber crest towards the leading edge and the thickness crest towards the mid chord as well as reducing the thickness.