旋翼／机体耦合动稳定性计算与试验的对比

A Comparison of Theory and Experiment for Coupled Helicopter Rotor Body Stability in Hover

采用带外伸量及弹性约束的当量铰桨叶模型，考虑了旋翼挥／摆结构耦合及动力入流非定常气动力，建立了悬停状态旋翼／机体耦合动稳定性分析方法，适用于星形柔性及无铰式等旋翼系统。分析时挥舞、摆振、机体运动及动力入流均以复数变量表示。通过各自由度之间相互作用分析，揭示了动不稳定的机理及动力入流的影响原因。本文分析了ＮＡＳＡ等研究机构的孤立旋翼及旋翼与机体耦合动稳定性标准试验，计算结果与试验值的吻合程度较美国同类研究好。分析表明，动力入流对模态阻尼有较大影响。

An analysis method for calculating the aeromechanical stability of a helicopter rotor body coupling system in hover is developed.In the method ,the blades are treated as rigid ones with offset and spring restrained hinges and with structural coupling between flap and lead lag motion for the purpose of being applicable to hingeless or starflex rotors.Dynamic inflow model is used in the paper for unsteady aerodynamics of the rotor. The flap,lead lag and body degrees of freedom and the dynamic inflow are all expressed in complex variables.An analysis of mutual excitation of different degrees of freedom is also made to reveal the mechanism of the instability and the way of the influence of dynamic inflow on the instability.Stability calculations using the method developed in the paper are performed on a standard test model designed and tested by the NASA and the other U.S.research institutions. The agreement between the prediction in the paper and the test data is better than that of the most comparisons published in the literature.Analysis shows that the influence of dynamic inflow on the modal damping of the system is significent and the effect on the modal frequency is small.