INFLUENCE OF GEOMETRIC SHAPE OF RECESS ON THE PERFORMANCE OF A SIX-POCKET HYDROSTATIC/HYBRID JOURNAL BEARING SYSTEM

Abstract

he multi-recess hydrostatic/hybrid journal bearings are currently finding numerous applications in machine tool industries, test equipments, rolling mills, reactor coolant pumps, liquid rocket engines and in nuclear applications. Their wide acceptability in the engineering applications is mainly owing to their excellent characteristics in respect of high fluid film thickness, high load carrying capacity at zero and low speed, high accuracy of precision and location, long life and smooth operation, low friction and minimum temperature rise, large fluid film thickness and excellent dynamic characteristics. A review of the available reported studies concerning multi-recess hydrostatic/hybrid journal bearing systems has been presented in the literature. After going through the literature it has been observed that the performance of hydrostatic/hybrid journal bearing systems depends on number of parameters such as number of pockets, recess geometric shape, type of restrictors, bearing flexibility, fluid inertia effect, bearing geometry and operating parameters etc., further it was observed that the shape of recess in most of the studies undertaken was rectangular and very few studies related to other shapes i.e., circular, elliptical, triangular etc., have been attempted so far. Further it has been observed that the available studies, which consider the influence of recess geometric shape on the performance of multi-recess hydrostatic/hybrid journal bearing systems , are limited to four-pocket hydrostatic/hybrid journal bearing systems, but there is no study reported for six-pocket hydrostatic/hybrid journal bearing system with different geometric shape of recess. Therefore, the present work is planed to study of six-pocket hydrostatic/hybrid journal bearing system with different geometric shape of recess for the same geometrical and operating parameters of the journal bearing system. For computing the bearing performance characteristics, the Reynolds equation governing the flow of lubricant in the clearance space along with the restrictor flow equations as constraint together with the appropriate boundary conditions and a suitable iterative scheme is used to get the results. To accomplish this task a computer program based on finite element analysis has been developed. The study indicates that the performance of a compensated journal bearing system gets affected significantly due to geometric shape of recess and number of recess operating in hydrostatic/hybrid mode