Numerical analysis of the performance of an aerostatic thrust bearing with internal porous resistor

• Main Authors: Yi-Ting Chen, 陳怡廷
• Other Authors: Sy-Wei Lo
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/55701162060642881456

碩士 === 國立雲林科技大學 === 機械工程系碩士班 === 99 === Gas hydrostatic bearing, which has good bearing capacity and rigidity and has been mainly used in tool machine, now are increasingly applied to various industries. In this thesis, a novel thrust bearing which adopts a porous tube as restrictor is proposed; the air flux through the restrictor is controlled by the penetration depth of either an internal pin or an external collar. The computational fluid dynamics software, CFDRC, is employed to simulate the effects of the air gap and the pin/collar depth on the flow field, bearing capacity and static rigidity. The results showed that the air pressure dropped drastically when the air flows through the porous restrictor and the bearing capacity reduced as pin/collar moving inward the tube, particularly for thick gas film. As for the bearing rigidity, the air volume flux increased linearly with the pin/collar depth in the case of small depth region and eventually became saturated as the depth turned deeper. The simulation of the velocity field showed that the penetration of the internal pin could not effectively block the air infiltration and still, considerable amount of air flowed along the axial direction in the porous domain; when the collar was adopted, instead of moving directly towards the exit, the air fulfilled the whole chamber before it reached the outlet. Therefore the two mechanisms were proved unable to delicately control the air flux. Furthermore, replacing the flux adjustor parts such as the pin and the collar with a shorter porous tube yielded no additional help for the bearing rigidity. Among the three grain sizes of porous tube: 2μm, 5μm and 10μm, it was found that the highest bearing capacity could be obtained with the 10μm-grain tube in the case of minimum air gap.