直升机双叶旋翼/旋翼轴系统耦合动稳定性分析和试验

Analysis and Test of Coupled Dynamic Stability of Helicopter Twin Bladed Rotor/Rotor Shaft System

研究了直升机双叶旋翼桨叶摆振与旋翼轴弯曲的耦合振动，分析了系统三个模态固有频率随转速增长的变化趋势。着重研究了耦合各模态中存在着不稳定区的模态，并讨论了桨叶质量、旋翼摆振方向刚度、旋翼轴弯曲刚度对此模态不稳定区的影响。利用实物在组合台架上进行试验，测量了旋翼、旋翼轴及其支持系统的动应变，找出了旋翼谐波激振力作用下的共振点，从而验证了上述分析结果。本文还通过改变系统参数，检验了系统固有频率的变化情况，进一步验证了上述分析模型，并据此提出了提高临界转速避免出现不稳定性的设计措施。

The coupled vibration of blade lead lag motion and rotor shaft bending of a twin bladed rotor helicopter is investigated. An analytical model is established. The modal frequency and modal damping of the three modes of this coupled system are analysed, especialy the mode existing in an unstable rpm region.The influence of blade mass, lead lag stiffness and shaft bending stiffness on the instability is also investigated.This rotor system has been tested on a test rig. The dynamical stresses have been measured and the resonance frequencies have been found. By changing blade mass, lead lag stiffness and shaft bending stiffness, the start rpm of the unstable region is increased more than 90 r/min. The test data have verified the analysis and calculation. According to the results of the test and analysis, a comprehensive method to avoid the maximum design rpm falling into the unstable region is suggested.