Theoretical and Experimental Investigation of Oil Ring Bearings

Heshmat, H. “Theoretical and Experimental Investigation of Oil Ring Bearings,” Proceedings of EPRI Rotating Machinery Dynamics, Bearing and Seals Symposium, September 1986.

A theoretical and experimental investigation was conducted on the behavior of oil ring bearings.  Most oil ring bearings run under starved conditions, since only a small portion of the oil lifted up by the ring is actually delivered to the bearing clearance.  Studied and reported herein are the effects of an incomplete fluid film on the eccentricity locus, the extent of the film, the average and maximum temperatures, flow, and power loss as functions of the amount of lubricant delivered to the bearing.  An optimum length-to-diameter ratio was noted for oil ring journal bearings which is on the order of 0.6 to 0.8.  An optimized thrust bearing having an 80% tapered and a 20% flat land at the end of the pad was analyzed.  The analysis was based on the assumption that the incomplete fluid film starts along a radial line inside the pad.  Results are given for starvation levels ranging from 5% of the required flow to full film lubrication.  A series of tests  conducted on a 12-pad thrust bearing showed excellent agreement with the theory and confirmed some of the essential conclusions of the analysis, namely, that the effects of starvation accelerate below the 50% starvation line and that the start of the incomplete film depends only on the level of starvation and not on the operating conditions or film thickness. 

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