直升机不平衡旋翼动力学建模与轴心运动轨迹分析方法研究

This paper studies the forward flight dynamic model of tilt rotor unbalanced load proposed by Johnson, and applies its blade analysis method to the modal analysis of helicopter rotor system. Under the assumption of rigidity, the flapping and shimmy motion equations of helicopter rotor blade under the combined action of elastic damping and inertial force are derived, and the corresponding motion equations in fixed and rotating coordinate systems are given. By introducing the assumption of uniform inflow and linear torsion, the theoretical analytical solution of the equation of motion is obtained. Then, using the superposition principle, the axial motion equation of the hub is obtained; Newmark method is used to solve the vibration differential equation, and finally the axis motion trajectory of helicopter rotor is obtained. Taking a helicopter rotor system as an example, the accuracy of the rotor blade modal analysis method proposed in this paper is verified, and the optimal solution step selection method considering both calculation accuracy and efficiency is given. The hub axis trajectory under typical flight state is predicted, which provides a basic method and technical reference for the design of helicopter rotor system.