Some influencing factors of rotor vibratory loads prediction under high speed state

Based on the rotor airflow environment and blades movement, which would be produced when the helicopter flighted forward with high speed. It was analyzed the influence on the hub vibratory loads prediction by unsteady aerodynamics model, dynamic stall model, induced-flow distribution, elasticity deformation of blade, synthesization of hub loads and the method of numerical calculation. The hub load model includes the Leishman-Bed-does unsteady dynamic stall model, dynamic inflow theory and coupled blade movement between flap and torsion. The state-space method was used to solve the equation, which was fit for computer calculation. A calculation program was built up. Comparing calculational results of several models, it is revealed that various analysis models have great influence on hub vibratory loads prediction precision, and that aerofoil stall and induced velocity distribution are primary influencing factors. It is appropriate that more advanced induced inflow model and unsteady aerodynamics are introduced in hub vibratory loads prediction.