旋翼系统模态阻尼数值计算方法

摘要

首先基于Hamilton原理建立旋翼系统动力学模型,计算旋翼的振频和振型,然后对稳定悬停状态下的桨叶进行某阶模态的激励,并在旋翼重新达到稳定状态后停止激励,截取旋翼系统自由振动信号,用移动矩形窗法计算旋翼系统的模态阻尼.这种计算系统模态阻尼的数值方法能够对旋翼系统在不同工况下的各阶模态阻尼进行仿真,而且在仿真过程中可以根据桨叶振型将激励按相同相位施加于各自由度上,使桨叶只按该阶振型振动.使用该方法可以突破旋翼动力学试验中激振位置、激振频率与相位的限制,获得旋翼系统更全面的动力学特性.%A dynamics model of the rotor system based on Hamilton principle is established to compute vibration frequency and modes. The excitation at the frequency of a certain mode is applied to blades with the rotor in a stable hover state, and withdrawed when the rotor arrives at a new stable state. The response of the blade in the free decay progress is recorded. Modal damping is calculated by using the moving-block method. This method can compute any modal damping of the rotor system under different working conditions. Moreover, excitation can be applied to each degree of freedom of the blade according to the mode with the same phase, so that the blade vibrates according to this mode. The method breaks through the limitation of excitation location, frequency and phase in the rotor dynamics test to obtain comprehensive dynamic characteristics of rotor systems.