Flow field in clearance of dynamic pressure gas foil bearing withpartical slip
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摘要:
为揭示界面滑移对动压气体轴承间隙流场的影响机理，以波箔型动压气体径向轴承为研究对象，建立周向非一致滑移修正雷诺方程并采用超松弛迭代法进行求解，分析了转速、偏心率、间隙高度和箔片变形等因素变化下滑移对轴承间隙内流场的影响。结果表明：随着转速的增大或间隙高度的减小，流固界面由无滑移状态转变为静子侧滑移状态，并最终达到两侧均滑移状态，转子侧从压力上升区、静子侧从压力下降区向两侧滑移区域面积和速度逐渐增大；而偏心率的增大仅会导致滑移速度增大，而滑移区域面积几乎不变；箔片变形使滑移速度场呈现阶梯状分布。非一致滑移对最高气膜压力最大影响可达17%。速度梯度和压力场显著变化诱导界面剪应力和极限剪应力复杂演化而产生上述规律。
Abstract:In order to reveal the effects of the slip state on the flow field evolution under different working conditions of the dynamic pressure gas foil bearing, taking the dynamic pressure gas foil bearing as the research object, the modified Reynolds equation for circumferential partial slip was established and solved by the over-relaxation iteration method. The influence of slip on the flow field in the bearing clearance was analyzed under the change of rotating speed, eccentricity, clearance height and foil deformation. The results showed that with the increase of rotating speed or the decrease of clearance height, the fluid-solid interface changed from no slip state to the stator side slip state, and finally reached the slip state at both sides. The area and velocity of the slip region on the rotor side from the pressure rise region and the stator side from the pressure drop region to both sides gradually increased. However, as the eccentricity increased, the slip velocity on both sides increased gradually, and the slip area was almost unchanged. The deformation of the foil caused the slip velocity field to exhibit a stepped distribution. Partial slip had a maximum effect of 17% on the highest film pressure. The reason for the above law is that the changes of velocity gradient and pressure field make the interface shear stress and ultimate shear stress change complexly.
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Key words:
- dynamic pressure gas bearing /
- microscale /
- foil /
- interface slip /
- flow field
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图 9 无量纲滑移速度随转速变化云图
Figure 9. Diagram of dimensionless slip velocity at different rotating speeds
图 10 不同转速下剪应力变化图
Figure 10. Variation diagram of shear stress at different rotating speeds
图 11 不同转速下无量纲滑移速度和压力图
Figure 11. Dimensionless slip velocity and pressure diagram at different rotating speeds
图 12 无量纲滑移速度随偏心率变化云图
Figure 12. Diagram of dimensionless slip velocity at different eccentricities
图 13 不同偏心率下剪应力变化图
Figure 13. Variation diagram of shear stress at different eccentricities
图 14 不同偏心率下无量纲滑移速度和压力图
Figure 14. Dimensionless slip velocity and pressure diagram at different eccentricities
图 15 无量纲滑移速度随间隙高度变化云图
Figure 15. Diagram of dimensionless slip velocity at different gap heights
图 16 不同间隙高度下剪应力变化图
Figure 16. Variation diagram of shear stress at different gap heights
图 17 不同间隙高度下无量纲滑移速度和压力图
Figure 17. Dimensionless slip velocity and pressure diagram at different gap heights
图 18 有箔片时轴承无量纲滑移速度图
Figure 18. Dimensionless slip velocity diagram of bearing with foil
图 19 z=L/2截面处无量纲滑移速度和压力图
Figure 19. Dimensionless slip velocity and pressure diagram on z=L/2 section
表 1 计算工况
Table 1. Calculation conditions
参数 数值 间隙高度c/µm 40～160 转速N/104 （r/min） 4～13 偏心率ε 0.2～0.8 箔片数量M 8 长径比L/d 0.8 转子半径R/mm 30 平箔厚度tp/µm 76.2 波箔厚度tb/µm 76.2 单位波箔长度S/mm 4.064 单位波长跨度2l/mm 3.434 弹性模量Et/GPa 207 
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