A. M. Mikula, Research Engineer
Kingsbury, Inc., Philadelphia. Pa. 19154
An analysis of tilting-pad thrust bearing operating temperatures is described. The analysis includes an evaluation of various temperature locations based on their ability to reflect bearing operating conditions. Experimental results for a 267-mm (1O.5-in) 8-pad thrust bearing indicates that while a babbitt location on the trailing edge of a pad is often the hottest, the 75/75 percent location provides temperature data on the high-pressure region of the pad. Babbitt temperatures also provide a convenient indicator of the transition from laminar to turbulent flow in the oil film.
Bearing temperatures generated during the operation of a tilting-pad thrust bearing can provide a convenient means of assessing bearing performance. Widespread use of thermocouples and resistance temperature detectors (RTD's) has made possible the collection of this potentially valuable temperature data. Unfortunately, selecting the proper location(s) to place these devices is complicated by the numerous candidates within the bearing or lubricant. Unless the proper location(s) is monitored, the temperature measurements made will prove to be very poor indicators of overall bearing performance. Selection should be based on the ability of the selected location to reflect actual operating conditions, and not on the ease of installation of the measuring device.
This paper presents the results of a series of tests conducted on a tilting-pad thrust bearing to investigate the temperature behavior of various locations. Thermocouples were employed to measure the temperatures of the bearing pads and the lubricant.
The bearings were evaluated using a light turbine oil with a viscosity of 0.027 Pa·s @ 37.8°C and 0.006 Pa·s @ 98.9°C (150 ssu @ 100°F and 43 ssu @ 210°F) supplied at 46°C (115°F), for applied loads ranging from 0-3.45MPa (0-500 psi) and shaft speeds ranging from 4000 to 13,000 rpm.
The influence of lubricant supply method and flow rate are also evaluated. By reporting the influence of operating conditions on various locations within the bearing and lubricant, it is hoped that this paper will provide the information necessary to select the proper location to monitor bearing performance.
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