Performance Optimization of Variable-Speed and Variable-Geometry Rotor Concept

This paper discusses the application of a particle swarm optimization technique to a rotor dynamics analysis to perform multivariable optimization for minimizing power output for a variable-speed variable-geometry rotor system. A UH-60A Black Hawk helicopter rotor operating at a weight coefficient of Cw=0.0065 is taken as the baseline configuration to study the impact of power reduction through speed and geometry optimization. With the objective of keeping the computational cost low, a rotor dynamics model with the assumption of rigid blades having only flap degree of freedom is developed and coupled to a nonlinear aerodynamic model that has airfoil lookup tables, attached unsteady aerodynamic model and Drees inflow model. The rotor dynamics model is then validated using the flight-test data available in literature. The main rotor power is taken as the fitness function for the particle swarm optimization, and single-variable and multivariable optimizations are carried out to systematically establish the r...