Helicopter rotor performance improvement by piecewise dynamic blade twist

Abstract

Piecewise dynamic twist is studied as a method for reducing rotor power and improving rotor performance. A rotor performance calculation model is established based on the anisotropic composite moderate deformation beam model and used to power prediction and flow field analysis at different flight speeds. The theoretical prediction is consistent with the flight test data, which verifies the validity of the analysis model. The blade is divided into inner and outer segments in the radius direction according to the airfoil distribution of UH-60 helicopter. The effect and its mechanism of the piecewise dynamic twist on the rotor power is investigated from the point of view of the angle of attack and lift-to-drag ratio distribution over the disk. Overall, the effect is proportional to the amplitude of the dynamic twist, changes periodically with the phase angle, and increases first and then decreases with the flight speed. A set of piecewise dynamic blade twist schemes are obtained by the traversal method, which are better than the linear negative twist scheme at any flight speed.