Aeroelastic fluid dynamics assessment of performance and vibration on active twisting rotors
Rinaldo Steininger, George N. Barakos
Abstract
The effects of passive, and higher-harmonic rotor blade twist on helicopter main rotors are investigated. High-fidelity CFD is used for calculations due to the demanding flow conditions considered, including high blade loading, and high-speed cases. A strong structural coupling scheme is employed for enhanced performance and vibration predictions. Quantitative predictions are made for the effects of blade twist in hover, and the results showed: figure of merit improvements of up to 1 count per degree of twist, and diminishing returns with increasing twist. In high-speed level flight, the higher twist blade showed 18% increased vibration. A 2/rev active twist input shows vibration reductions of 22% in high-speed and 8% at high load cases. The active twist achieved a marginally improved aerodynamic efficiency at high-speed, and reduced the aerodynamic rolling moment in the dynamic stall conditions.