Effects of Tilt on the Performance of Hydrostatic Thrust Pads

Abstract

The majority of hydrostatic thrust bearings are designed on the assumption that the bearing surfaces are parallel but, with the possibility of manufacturing and assembly errors and structural deformations, this condition is rarely, if ever, achieved in practice. With the increasing demands being made in modern machinery, more detailed design information is required. An experimental and theoretical investigation was carried out into the effects of tilt on the operation of circular hydrostatic thrust pads, the results of which show that, for static conditions, the characteristics of a tilted pad can be reliably predicted, assuming the lubricant to be isoviscous. With this information, a thrust pad can be designed to operate in any specified tilted configuration or can be incorporated in a rigorous structural design. In many applications, however, it may be difficult to specify the tilt and in such situations it is more useful for the designer to have some indication of how the operating conditions may be modified by tilt when the design is based on parallel surfaces. For a system which is supplied from a constant pressure source through a viscous external restrictor, the modified operating conditions can be predicted. The effect of tilt on the operating conditions depends on the pad geometry and design resistance ratio but significant changes may occur in mean pad clearance, required flow rate and static stiffness. Although this investigation was limited to static conditions, the results are still valid for sliding conditions where the hydrodynamic effects are small compared with the hydrostatic contribution. The general effects of tilt observed with circular pads are indicative of what may be expected with pads of other geometries.

Performance of hydrostatic circular thrust pad bearing operating with Rabinowitsch fluid model

“…The relevant boundary conditions for fluid film pressure variation in the above-mentioned differential equations (13) and (14) are considered as Figure 2. Finite element mesh of thrust bearing.…”

Combined influence of couple stress lubricant, recess geometry and method of compensation on the performance of hydrostatic circular thrust pad bearing

“…Numerous efforts have been undertaken by many researchers 1–27 in an attempt to improve the tribological performance of this class of bearing. Initially, Brown 3 derived analytical expression for dynamic characteristics of hydrostatic thrust bearing system using equivalent spring damper system.…”

“…However, errors incurred during structural deformations, manufacturing, and assembling induced some amount of tilt among the bearing surfaces. A theoretical and experimental investigation 9 was carried out to predict the performance of circular hydrostatic thrust pad bearing while taking into consideration the influence of tilt. Osman et al.…”

“…However, adding traces of these additives results in lubricant exhibiting non-Newtonian behavior. Traditionally, investigations 3–11 have been carried out assuming the lubricant to be Newtonian in nature. With the availability of non-Newtonian lubricants in industry, the applicability of this lubricant in various lubrication regimes has attracted the attention of many researchers.…”

Finite element analysis of tilted thrust pad bearings of various recesses shapes considering thrust pad flexibility

“…Therefore, various studies have been performed to compute the effect of tilt on bearing performance. [9][10][11][12][13][14][15][16] It was reported that tilt in shaft significantly changes the bearing performance and results increase in temperature. Beek and Segal 9 computed numerical solution for tilted hydrostatic multipad thrust bearing.…”