Blade Twist and Disc Loading Effects on the Rotor Aerodynamics in the Vortex Ring State Modes
DOI:
https://doi.org/10.1590/jatm.v18.1440Keywords:
Rotor, Blade twist, Rotor disc loading, Vortex ring state modes, Free wake modelAbstract
The article is dedicated to parametric studies of the effect of the rotor blade twist θtw and the rotor disc loading P values on rotor aerodynamics in the vortex ring state (VRS) modes. Sixteen rotor configurations with a loading P in the range of 150 to 600 Pa (in hovering), with a blade twist θtw in the range of 8° to -16°, have been considered. The original free wake model of a rotor has been used for a numerical study. For each of the 16 rotors, the vertical (axial) descent modes (angle of attack of a rotor αR = 90°) in the range of descent speeds Vy = 0 to 26 m·s-1 were investigated. For two selected rotors, the steep descent modes (αR = 80° to 20°) were additionally investigated. The dependences of rotor thrust on the velocity of descent for a fixed blade pitch angle θ(Vy) were analyzed. The boundaries of the VRS modes area have been plotted. The obtained results have demonstrated the significant influence of the θtw and P parameters on the rotor aerodynamics and on the VRS area boundaries. The data obtained can be used in preliminary design and in the process of choosing initial parameters of the helicopter main rotor, and are also useful in developing the future concepts of variable-twist rotors.
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