边界滑移对波箔型动压气体轴承静特性的影响

Effects of Sliding Boundary on Static Characteristics of Aerodynamic Compliant Foil Bearing

关键词:  波箔  动压气体轴承  边界滑移  极限剪应力  轴承静特性

Key words:  Bump foil  Aerodynamic compliant foil bearing  Sliding boundary  Ultimate shear stress  Static characteristics of bearing

摘要:

为获得流固边界滑移状态对动压轴承性能的影响，以波箔型动压气体轴承为研究对象，建立极限切应力模型下不同滑移状态的气膜压力及厚度方程，利用差分迭代法耦合求解，分析不同边界滑移状态时轴承静特性随滑移相关参数的变化规律。研究结果表明:与无滑移状态相比，轴面侧滑移对轴承静特性不利，箔片侧滑移对轴承静特性有利，滑移对承载力额最大影响幅度可达20%，对偏位角的最大影响幅度可达10°；两侧均存在滑移时轴承静特性下降，影响幅度小于前两者。当轴承转速、偏心率以及润滑气体动力粘度增大时或者轴承间隙减小时，均会使滑移对承载力的影响增大、对偏位角的影响减小。

Abstract:

The status of sliding boundary between fluid and solid has significant effect on aerodynamic compliant foil bearing. The model of aerodynamic compliant foil bearing was built， whose gas film pressure and thickness equations with different sliding conditions in the fluid-solid boundaries were established in consideration of ultimate shear stress. Moreover， they were solved by iteration using finite difference method， in order to gain the variety law about the static characteristics of bearing with variation of the parameters in different sliding conditions， which are associated with sliding boundary. The results show that the static characteristics of bearing is reduced by slipping only in the journal surface and enhanced by slipping only in top foil surface compared with no slipping condition. And the slipping affects the static characteristics of bearing as much as 20% bearing capacity and 10° in the deflection angle. Moreover， the static characteristics of bearing are weakened when slipping coexists， whose degree of influence is less than the above two slipping conditions. In addition， the influence of any sliding conditions on capacity is amplified and on deflection angle is cut down， when rotation speed， eccentricity or gas dynamic viscosity increase. And the same rules occur when radius gap decreases.