Session: 03-16-01: Manufacturing: General

Paper Number: 113022

113022 - Experimental Determination of Load-Carrying Capacity of Modified Tapered-Land Hydrodynamic Thrust Pad Bearings 

The objective of this study is to investigate the thrust load carrying capacity of a manufacturable modified tapered-land hydrodynamic thrust pad bearing through hydrodynamic oil film pressure development. Experimental determination of thrust bearing load capacity is limited by the test equipment applied load capability which may be unequipped to create specific load magnitudes for application-sized bearings. Theoretical analysis of Reynolds equation suggests there is a linear relationship between the number of pads on a thrust pad bearing and the maximum thrust load a bearing can support. To test bearings at more extreme conditions within a laboratory environment, a method for increasing specific load on hydrodynamic thrust bearings is introduced and experimentally evaluated which allows for the distributed surface pressure experienced by the bearing pad to be effectively doubled without need for increased testing capabilities. Experimental testing is performed at the Hydrodynamic Bearing Testing Lab at Ohio University comparing two bearing samples developed within the machining capability envelop of Ohio University’s fabrication facility. The first test sample has eight active thrust pads evenly arranged on the bearing surface whereas the second test bearing has only four active thrust pads of the same size evenly arranged. The eight-pad hydrodynamic thrust pad bearing design is modified so that only four of the pads are viable for hydrodynamic pressure development. Each bearing is subjected to static thrust loads of 100, 200, 300, 400, and 500 lbf at constant speeds of 1,500, 3,000, 4,500, and 6,000 rpm for a total of 20 test conditions per bearing. The modified and unmodified bearings are kept at constant lubricant temperature while pressure development on the pad surface is measured using integrated pressure transducers. Active bearing temperature and minimum oil film thickness are also measured. The experimentally measured hydrodynamic pressures are then compared to an analytically predicted values determined using Reynolds equation. Results from this study show that reduction of the active thrust bearing surface area by half was shown to increase the hydrodynamic pressure acting on the bearing by 200%. Further, the analytically predicted values of hydrodynamic pressure agreed closely with the experimentally gathered values. Removing active thrust pads is proven to effectively multiply the specific load on the bearing pad and create a more extreme operating condition under lower thrust force without increasing the bearing size envelope. The present study also reveals that this method of bearing modification has potential applications in expanding laboratory test capabilities with hydrodynamic thrust pad bearings while satisfying manufacturing capabilities of a fabrication facility. Hydrodynamic thrust bearings with theoretically predicted load limits beyond a test stands usual thrust capability can be experimentally evaluated using this method.

Presenting Author: Muhammad Ali Ohio University

Presenting Author Biography: Neil. D. Thomas, CAMP Director, and Graduate Chair of Mechanical Engineering at Ohio University

Authors:

Jenna Trammell Ohio University
Collier Fais Ohio University
Muhammad Ali Ohio University
Rick Walker MIBA Bearings