Research On Bearing Characteristics And Stability Of Precision Centrifuge Gas Bearing

As the calibration equipment of accelerometer, Precision Centrifuge demands a high rotation accuracy. The traditional lubrication methods can’t meet the requirement of accuracy. Gas bearing has the advantages of small friction, high precision and wide range of work, etc. It is widely used in the precision centrifuge system. Compared with the traditional lubrication, it has the disadvantages of insufficient carrying capacity and poor stability. Therefore, studying on bearing characteristics and stability of gas bearings are of great significance to ensure the accuracy of precision centrifuge system. Based on numerical simulation technology,10-6 Precision Centrifuge gas bearing is used for the study of bearing characteristics and stability. The research mainly includes the following aspects:(1) Research on bearing characteristics of precision centrifuge gas bearing. The numerical simulation technology was used to analyze cross-scale, dynamic pressure effect and compressibility of gas bearing. By comparing with the experimental data, its effect on calculation results was studied. Based on the study, the simulation method of gas bearing was established. By the use of symmetry and period boundary, the model of precision centrifuge gas bearing is established. Starting from the analyzes of pressure fluctuations of the flow field, the influence of the supply pressure, eccentricity and attitude angle on capacity and stiffness is studied.(2) Research on rotation error by the coupling effect of bearing-rotor system of precision centrifuge. For bearing-rotor system of precision centrifuge, the bearing capacity related to eccentricity and the supply pressure was derived by a nonlinear fitting function. The dynamic characteristic of bearing-rotor system is established based on the finite element method. The response under the influences of gravity and unbalanced force and nonlinear gas film force is calculated. The influence of the rotation rate, the supply pressure and mass eccentricity on rotor motion is analyzed. The trajectory results showed that under small eccentricity the rotating error well meets the requirements of rotational error.(3) Research on Micro Self-vibration of precision centrifuge gas bearing. Large eddy simulation is used to analysis vortex flow of gas bearing at the outlet of orifice restrictor. The results show that there are flow zones with large viscosity and low pressure areas in the flow field. The reasons of micro self-vibration of precision centrifuge gas bearings are studied from the perspective of the flow field. The effect of the size of gas pocket, the structure shape of the gas pocket, and the supply pressure on the micro self-vibration is researched. The results showed that pressure fluctuations on bearing surface are weakened by reduce the radius or height of the gas pocket. Gas bearing without gas pocket doesn’t exist vortex flow. By rounding the gas pocket the fluctuations in the flow field are weakened. The supply pressure significant effect on pressure fluctuations of the bearing surface, when the supply pressure is increased to a critical value, the pressure on the bearing face could fluctuate wildly.