Investigation of Active Rotor Design and Control for Performance Improvement

Abstract

A computational investigation was conducted to identify the optimal performance of a rotor with an active camber morphing mechanism using up to twice-per-revolution (2P) control input. Using rotor comprehensive analysis with an elastic blade model and a free vortex wake for the aerodynamics model to ensure computational efficiency, a parametric study of design and control variables was carried out to identify their influence on rotor performance. The same computational framework was used to obtain optimal control inputs that led to best performance using 2P individual blade control (IBC) via pitch-link inputs and 2P active twist control. The relative potential of the three active mechanisms to improve rotor performance was studied and compared. A level flight condition at μ = 0.3 and CT /σ = 0.089 was used throughout this investigation. IBC or active twist both yielded maximum performance improvements of 1.8% in terms of power reduction. Optimal isolated 1P and 2P active camber actuation resulted in performance improvements of 3.6% and 3.1%, respectively. Using the best combination of geometric design and optimal superimposed 1P+2P actuation, a rotor power reduction of 4.4% was obtained. Overall, the rotor performance gains obtained using each active rotor mechanism that was investigated were attributed to a more uniform distribution of thrust over the rotor disk.