动静压气体轴承-柔性转子系统的动力学特性

Experimental Study on Dynamic Characteristics of Gas Hybrid Bearing-Flexible Rotor System

针对高速动静压气体轴承-柔性转子系统中存在的气膜振荡现象,考虑轴承供气压力对轴系动力学特性的影响,开展了转子系统动力学特性的实验研究。采用模态实验分析的方法,得到了转子临界转速区域,为升速实验方案的制定以及气膜振荡机理的分析提供依据。采用分岔图、三维谱图、轴心轨迹等非线性振动测试与分析方法,研究了供气压力对气膜振荡特性的影响。实验结果表明,轴承供气压力对转子的升速响应和失稳门槛转速有着重要的影响。随着供气压力的增加,消除了二阶模态气膜振荡,同时,变轴承供气压力方案下1阶模态气膜振荡的幅值比0.4 MPa下1阶模态气膜振荡的幅值小。另外,较高的轴承供气压力能够提供较大的轴承直接刚度,因此,平动、锥动以及1阶弯曲固有频率随轴承供气压力的增加而增加。

For gas whipping of a high-speed rotor-bearing system with gas lubrication,the experimental study of the dynamic characteristics of a bearing-rotor system is carried out that takes into account the influences of bearing supply pressure on the dynamic characteristics of the shaft system.Critical speed regions are obtained with modal experiments.This provides the basis for establishing acceleration plans and a gas whipping mechanism analysis.The influence of bearing supply pressure on gas whipping is obtained using nonlinear analysis methods,including a bifurcation diagram,frequency coupling 3-D plot and orbit plot of the shaft center.The experimental results show that the vital effects of the reasonable bearing supply pressure on rotor start-up responses and threshold speed of instability.As the supply pressure rises,the second mode whip vibration is eliminated,and the amplitude of the first mode whip vibration at the varying supply pressure is smaller than that in a single supply pressure at 0.4MPa.Higher supply pressures also offer larger bearing direct stiffness,so cylindrical,conical whirling and first natural frequency increase with bearing supply pressures.