Analysis of the dynamic characteristics of downsized aerostatic thrust bearings with different pressure equalizing grooves at high or ultra-high speed

Ruzhong Yan,Haojie Zhang

doi:10.1177/16878140211018078

Abstract

This study adopts the DMT(dynamic mesh technology) and UDF(user defined functions) co-simulation method to study the dynamic characteristics of aerostatic thrust bearings with equalizing grooves and compare with the bearing without equalizing groove under high speed or ultra high speed for the first time. The effects of air film thicness, supply pressure, rotation speed, perturbation amplitude, perturbation frequency, and cross section of the groove on performance characteristics of aerostatic thrust bearing are thoroughly investigated. The results show that the dynamic stiffiness and damping coefficient of the bearing with triangular or trapezoidal groove have obvious advantages by comparing with that of the bearing without groove or with rectangular groove for the most range of air film thickness, supply pressure, rotation speed, perturbation amplitude, especially in the case of high frequency, which may be due to the superposition of secondary throttling effect and air compressible effect. While the growth range of dynamic stiffness decreases in the case of high or ultra-high rotation speed, which may be because the Bernoulli effect started to appear. The perturbation amplitude only has little influence on the dynamic characteristic when it is small, but with the increase of perturbation amplitude, the influence becomes more obvious and complex, especially for downsized aerostatic bearing.

Highlights

Aerostatic bearings are one of the most important parts of precise and ultra-precise machinery, which are widely used in aerospace, biomedicine, high-precision machine tools and measuring instruments
The simulation results about the influence of the air film thickness on the dynamic stiffness and damping coefficient for the aerostatic thrust bearing with or without groove at air supply pressure 0.6 MPa, rotation speed 20,000 r/min, and perturbation amplitude 0.4 mm are shown in Figures 9 and 10
The influence of the rotation speed on the dynamic stiffness and damping coefficient for the aerostatic thrust bearings with or without groove are investigated at the gas film thickness 12 m m, supply pressure 0.6 MPa and perturbation amplitude 0.4 mm, the rotation speeds of the rotational wall boundary condition are 100,000, 150,000, and 200,000 r/min respectively, which are shown in Figure 13(a) to (c)

Summary

Introduction

Aerostatic bearings are one of the most important parts of precise and ultra-precise machinery, which are widely used in aerospace, biomedicine, high-precision machine tools and measuring instruments. The effects of air film thickness, supply pressure, perturbation frequency, perturbation amplitude, rotation speed, and cross section of the groove on the dynamic characteristics of the aerostatic thrust bearings with pressure equalizing groove are analyzed in this research.

Results

Conclusion