气体动压轴承非线性动力学行为和稳定性预测

Nonlinear Dynamic Characteristics and Stability Prediction of Aerodynamic Bearings

以球面螺旋槽气体动压轴承为研究对象,建立三维微气膜瞬态流场数学模型,采用流体动力学软件,对轴承三维气膜压力场进行仿真分析,得到使轴承承载能力最大的结构参数和运行参数。研究在最大承载力下,不同转速和偏心率对气体轴承瞬态刚度系数和阻尼的影响规律,探索气浮轴承瞬态非线性动力学行为。模拟出转子受转速影响下的轴心轨迹图,研究轴承-转子系统的稳定性。研究结果表明:槽宽比、槽深比、偏心率对轴承承载特性的影响明显;提高转速和偏心率有助于轴承的稳定,但随着转速的升高,轴承转子系统的稳定性接近临界状态,导致轴承转子系统不稳定,而较大的偏心率,易导致轴承产生碰摩现象,也破坏了轴承的稳定性,因此,在轴承设计过程中应合理选择轴承的设计参数,提高轴承的综合性能。

In order to research the transient-state flow field characteristics of spherical spiral groove aerodynamic bearings, 3D micro gas film mathematical model of the gas bearings was established, and 3D gas film pressure field of the bearings was analyzed based on the FLUENT software of fluid dynamics to obtain the bearing structure parameters and operation parameters at the maximum bearing capacity.The effects of different speeds and eccentricity ratio on dynamic characteristic coefficients were studied at the maximum bearing capacity, and the transient nonlinear dynamic behavior of the gas bearings was explored.The axis orbit of the bearings at different speeds was simulated and the stability of bearings was researched.The results show that the bearing characteristics of the bearings are obviously influenced by the groove width ratio, groove depth ratio and eccentricity ratio. It is helpful to improving the stability of bearings by increasing the speed and eccentricity, but with the increasing of rotational speed, the stability of rotor bearing system is close to critical state ,which will lead to instability of rotor bearing system.While larger eccentricity is easy to cause the phenomenon of rub ,which will also destroy the stability of the bearing.Therefore, in the process of bearing design ,the rational parameters of the bearings should be chosen to improve the comprehensive performance of bearings.