Mission-based Optimal Morphing Parameters for Rotors with Combined Chord and Twist Morphing

Abstract

Two different helicopter rotor morphing concepts – namely, the linearly variable chord extension and the Shape Memory Alloy (SMA) based twist - under the framework of the European project SABRE are investigated for their optimal geometric parameters using a Particle Swarm Optimization (PSO) algorithm. Since the morphing parameters are dependent on the mission profile, three different missions representing typical helicopter applications are chosen. The optimization problem is posed both as single objective (power) and as multi-objective (power, tip elastic torsion and vibratory hub load). Based on the insights drawn from these investigations, a rotor is set up including both the morphing concepts in a single blade. The rotor with combined chord and twist morphing is shown to have better performance than the baseline blade while keeping the penalty on the elastic torsion and vibration to a minimum.