Study on static and dynamic characteristics of water-lubricated hydrostatic thrust bearings – Effect of feed hole inlet shape on bearing characteristics

Abstract

Recently, water-lubricated hydrostatic bearings have been attracting attention. However, when water is used as the lubricating fluid, the flow velocity of the feed hole used as a restrictor is higher than that of conventional oil-lubricated hydrostatic bearings, resulting in a larger feed hole inlet flow velocity, making it difficult to analyze its characteristics using conventional hydrostatic bearing analysis methods. Therefore, in this study, a general-purpose fluid analysis tool has been used to numerically analyze the internal flow of two types of pocket-type water-lubricated hydrostatic thrust bearings with different feed hole inlet geometries and found that the pressure loss at the feed hole inlet is large for water-lubricated bearings and that the flow inside the feed hole is different from that of oil-lubricated hydrostatic bearings. The orifice effect at the feed hole inlet is found to account for most of the restrictor function. Furthermore, it was shown that the pressure loss at the feed hole inlet can be increased by adopting a right-angle inflow structure for the feed hole inlet geometry, which can improve the static and dynamic characteristics of the bearing.