柔性转子——挤压油膜阻尼器系统的突加不平衡响应

Sudden Unbalance Responses of Flexible Rotor Supported in Squeeze Film Dampers

本文选择了一种可以无限逼近阶跃函数,具有无穷阶连续导数的表示转子突加不平衡的数学模型.用此模型分析了支承在同心型及非同心型挤压油膜阻尼器上的柔性转子的突加不平衡响应.研究了系统参数对突加不平衡响应的影响及不同转速下突加不平衡对系统双稳态响应的影响.证明了设计合理的挤压油膜阻尼器对突加不平衡具有抑制作用.此外,非同心型挤压油膜阻尼器抗突加不平衡的能力要比同心型挤压油膜阻尼器强,但非同心型挤压油膜阻尼器在突加不平衡时容易产生非协调响应.

In order to express the continuous process of sudden unbalance, a real function which can be differentiated for infinite times is introduced. It not only has the properties of step function, but can hold the continuity of the jumping process of sudden unbalance.The sudden unbalance responses of flexible rotor—SFDB system are analysed in this paper. For the case of constant rotating speed, it is found that the larger the bearing parameter B, stiffness ratio K, external damping ratio and mass ratio and the smaller the quantity of sudden unbalance, the short er the transient process of sudden unbalance response and the smaller the transient amplitude. But the quantity of sudden unbalance has no influence on the new steady state response.Sudden unbalance may cause nonsynchronous response to the system. If the new steady state response after sudden unbalance is still nonsynchronous, the amplitude of the new steady state response is almost the same with the transient amplitude although the transient process is shorter.For the case of accelerating through bistable region, if the sudden unbalance occurs before bistable region, as the sudden unbalance may cause large vibration amplitude, the system response will jump to the large solution of the bistable response and pass through the bistable region along the large solution with the increasing of rotating speed, then it will jump down to the small solution of the bistable response. If the sudden unbalance occurs in the bistable region, the sudden unbalance will not cause bistable jump and the response will pass through bistable region along the small solution of the bistable response although large amplitude is caused by sudden unbalance.The uncentralised SFDB is better than the centralised one in depressing the sudden unbalance vibration.