间隙环流作用下的转子动力学性能分析

为研究间隙环流对转子动态性能的作用规律,根据流体的连续定理和动量定理建立了描述间隙环流运动规律的偏微分方程组,采用线性摄动方法将间隙环流内流体压力的稳态量和动态量分离,求解得到间隙环流动态作用力的表达式.为验证该流场计算模型,搭建了一个实验装置.使用有限元方法建立实验台干转子的动力学模型,通过实验测试干转子的固有频率,对动力学模型中法兰连接处的接触刚度等参数进行标定.将间隙环流的动态作用力分解为质量矩阵、刚度矩阵、阻尼矩阵的形式,施加到干转子动力学模型上,得到湿转子的动力学模型.求解该模型得到转子的动力学特征参数对于转子转速的变化规律.通过对间隙环流试验模型进行计算和实验测试,验证了该模型的有效性.研究结果表明,间隙环流能显著降低转子的固有频率,并能够在一定的转速范围内造成转子失稳.

Dynamic Behavior of a Rotating Shaft Immersed in a Fluid Annulus

To investigate the influence of annular flow on the dynamic behavior of the rotor, partial differential equations are established to describe the flow in the annulus according to the continuum theory and momentum theorem. The linear perturbation method was used to separate the steady state part and the dynamic part of the flow field pressure in the annulus. The expression of the dynamic force generated by the annular flow was calculated. A test rig was built to validate the theoretical model. The dynamic model of the dry rotor in the test rig was established using the finite element method. The modal frequency of the rotor tested in the test rig was used to determine the contact stiffness of the flange in the rotor, and then the theoretical model was demarcated. The dynamic force of the annular flow can be expressed by combination of the mass matrix, damping matrix and stiffness matrix. The dry rotor model integrated with the dynamic force becomes the wet rotor model. The variation of the modal frequency and system damping of the wet rotor corresponding to the rotor speed were calculated. The theoretical results were validated by experimental results. The research shows that the annular flow can reduce the modal frequency and can induce the instability of the rotor in some speed domain.