Twodimension analytical theory and experiment of highvacuum externally pressurized gas thrust bearings
                                                   LI Lujun1,2, ZHU Yu2, ZHANG Ming2, HU Jinchun2
（1.China Institute of Water Resources and Hydropower Research, Beijing 100038, China;2.Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, China）

Abstract: Aiming to the problem of twodimension analysis theory of the performance of the externally pressurized highvacuum gas thrust bearings, the supply gas flow rate and the gas film depth and the stiffness of the externally pressurized highvacuum gas thrust bearings with the pressureequalizing groove were studied experimentally and numerically, and the two analysis model was built, which can be applied for three gas flow states, the viscous flow sate, the molecule flow sate and the intermediate flow state. Firstly, based on the principle of the vacuum flow conductance, the control equations of the twodimension analysis model were derived for three flow sates. Secondly, the experimental apparatus was built for the study of the externally pressurized highvacuum gas thrust bearings with pressureequalizing groove, and the flow rate of the gas bearing at different supply gas pressure conditions were obtained by measuring of the pressure of different points. Thirdly, the reliability of the twodimension analytical model was validated by comparison of the flow rate between the analysis model and the experiment. At last, by using of the analytical model, the gas film thickness and the static stiffness of gasbearings during the experiments were obtained at different supply pressure. The results indicate that as the load capacity keep constant the static stiffness increase firstly and then decrease with the increase of the supply pressure.

Key words: highvacuum gas bearings; externally pressurized gas bearings; twodimension analytical model; stiffness of gasbearing