平面静压气浮轴承垂直微冲击的稳定性

Stability to vertical impulse perturbation of plane externally pressurize gas bearings

为研究垂直微冲击引起的平面静压气浮轴承稳定性问题,利用线性摄动法,建立由稳态Reynolds方程、扰动Reynolds方程和轴承运动方程组成的微扰动分析模型,利用COMSOLMULTIPHYSICS软件中的PDE模块,获得了平面静压气浮轴承受到垂直微冲击后气膜内压强和气膜厚度随时间的变化过程。仿真试验表明:轴承的振动频率和阻尼系数与垂直微冲击的强弱无关,与气膜厚度和供气压强有关。轴承振动频率在不同冲击下,都约为200Hz。随供气压强增大,轴承阻尼系数减小。气膜厚度保持5μm时,供气压强小于0.8MPa时阻尼系数大于0,轴承稳定状态,供气压强等于0.8MPa时阻尼系数为0,轴承临界状态,供气压强大于0.8MPa时阻尼系数小于0,轴承不稳定状态。

Vertical micro impulses could create instabilities in plane externally pressurized gas-bearings,so the stability of gas bearings needs to be analyzed.A perturbation analysis model including the stable Reynolds equation,the perturbation Reynolds equation and the gas-film thickness perturbation equation was developed by combining the perturbation method with Newton＇s second law.The PDE solver in the comsol multiphysics software was used to solve for the pressure varieties in the gas film and the gas film thickness with time.The results show that the vertical micro impulses do not affect the vibration frequency and damping coefficients of the gas bearings.For different impacts,the frequencies were all about 200 Hz.However,the damping coefficients depended on the gas-film thickness and the supply pressure.For a gas film thickness of 5 μm and supply pressures less than 0.8 MPa,the damping coefficients is greater than 0,so the bearing is stable.For a supply pressure equal 0.8 MPa,the damping coefficients is 0,so the bearing was critical state.For supply pressures more than 0.8 MPa,the damping coefficients is less than 0,the bearing is unstable.