润滑气体及箔片材料对气体动压轴承动特性影响分析

Analysis of Lubrication Gas and Elastic Foil for Gas Foil Bearing Dynamic Characteristics

关键词:  气体动压轴承  动特性系数  气体动力粘度  泊松比  弹性模量

Key words:  Aerodynamic bearing  Dynamic characteristic coefficients  Gas viscosity  Poisson’s ratio  Elasticity modulus

摘要:

为研究润滑气体和弹性箔片材料特性对波箔型气体动压轴承动特性的影响,以Hydresil型波箔气体动压轴承为研究对象,建立气体流动控制方程和波箔弹性变形模型,通过有限差分法求解扰动方程获得动特性系数。数值分析了润滑气体动力粘度(4.2×10-6～4.6×10-5Pa·s)、轴承波箔片材料泊松比(0.15～0.45)和弹性模量(70～340GPa)对动特性系数的影响规律。结果表明,在偏心率和转速相同情况下,随气体动力粘度升高,动态刚度系数逐渐增大,且主刚度方向增大最为明显,最大可超过50%,动态阻尼系数也增大,且x方向增大最为明显,最大可达60%；随轴承箔片材料弹性模量的增大,动态刚度系数不断增大,动态阻尼系数在y方向上逐渐增大,在x方向上逐渐减小；轴承箔片材料泊松比对动特性系数影响较小。

Abstract:

Numerical study for effects of lubrication gas and foil material properties on bump-type foil aerodynamic bearing dynamic characteristics was performed by taking the gas bearing of Hydresil type as the research object. A gas flow control equation and the bump foil elastic deformation model were set up. The finite difference method was used to solve the model for obtaining the dynamic characteristics of gas foil bearings. With reference to the actual situation,the lubrication gas viscosity ranges from 4.2×10-6 to 4.46×10-5Pa·s,bump foil material Poisson’s ratio ranges from 0.15 to 0.45 and the modulus of elasticity ranges from 70 to 340GPa. Results show that under the same eccentricity and rotation speed,with the increase of viscosity,dynamic stiffness coefficients increase gradually,and the main stiffness coefficient increase most obviously and it can be more than 50%. The dynamic damping coefficients increase too,and the values at x direction increase most obviously,the maximum is 60%. Along with the increase of bearing foil material elastic modulus,dynamic stiffiness coefficients increase,dynamic damping coefficients at y direction gradually increase and at x direction it gradually decrease.Poisson’s ratio of bearing foil material has little influence on coefficients of dynamic characteristics.