Vibration loads analysis of coaxial rigid rotor in rotor interaction

旋翼干扰对共轴刚性旋翼振动载荷影响分析

Received: 6 March 2021

Abstract

A vibration load computing method for a coaxial rigid rotor was developed and applied to analyzing its vibration load in rotor interference. The structural dynamics model based on the medium-size deformation beam theory and the double-rotor aerodynamics model that contains unsteady free wake were jointly used to develop the coaxial rigid rotor's vibration load computing method. The wind tunnel test data of the XH-59A helicopter was used to validate this computing method. The vibration load of a rotor hub was analyzed in detail. The results show that the 3Ω harmonic wave amplitude of the vertical force F_z of the rotor hub and that of its pitch moment M_y decrease in high pitch angle, but the 3Ω harmonic wave amplitude of the roll moment M_x of the rotor hub obviously increases. The vibration load of the rotor hub increases with the decrease of the range of the coaxial rigid rotor; the roll moment and pitch moment of the rotor hub are sensitive to phase angle. The results also show that the increase of the 3Ω harmonic wave amplitude of the roll moment M_x is greater than the decrease of that of the roll moment M_y at the phase angle of 30° and that the level of vibration load of the rotor hub is minimum at the phase angle of 0° in forward flight.

摘要

针对旋翼干扰下的共轴刚性旋翼振动载荷问题开展计算分析。结合中等变形梁理论的结构动力学模型和含非定常自由尾迹的双旋翼气动模型，建立共轴刚性旋翼振动载荷计算模型。以XH-59A旋翼为研究对象，在模型验证的基础上详细分析旋翼俯仰角α、间距D以及交叉角Ψ对共轴刚性旋翼振动载荷特性影响。研究表明：增加旋翼俯仰角α会降低桨毂垂向力F_z和俯仰力矩M_y的3Ω谐波幅值，但会大幅增加滚转力矩M_x的3Ω谐波幅值，在高速前飞时利用俯仰角参数能调节桨毂谐波幅值水平；旋翼间距D越小，桨毂谐波幅值越高；交叉角Ψ对桨毂滚转力矩M_x和俯仰力矩M_y谐波幅值影响较大，在30°交叉角下滚转力矩M_x的3Ω谐波幅值增加量要高于俯仰力矩M_y的3Ω谐波幅值减少量，而0°交叉角下的桨毂振动载荷整体水平更低。