Testing, Analysis, and CFD Modeling of a Profiled Leading Edge Groove Tilting Pad Journal Bearing

Abstract

Testing and analysis of a profiled leading edge groove tilting pad journal bearing developed for light load operation is described. This bearing was designed for a generic, small, high speed steam turbine operating at projected loads of less than 25 psi (172.4 kPa) and journal surface speeds to 400 ft/s (122 m/s). On the second turbine application, a rotor instability was experienced with the oil flowrate reduced to optimize bearing steady state performance. This instability was eliminated by machining a taper on the exit side of the feed groove on each pad. At the reduced flowrate, the profiled groove bearing greatly improved the operating characteristics of the rotor system by reducing vibration amplitudes and stabilizing operation at speed. This paper is divided into two sections. The first section compares the rotordynamics analysis with test data that shows improved unbalance response and operating stability with the profiled groove bearing. The second section provides original insight of the effect of the profiled geometry on the bearing flow field using computational fluid dynamics models.

A Modified Oil Lubrication System with Flow Control to Reduce Crankshaft Bearing Friction in a Litre 4 Cylinder Diesel Engine

“…Generally, the bearings operate fully-flooded, with the lubricant filling the full width and circumference of the bearing. Previous studies suggest that bearing friction can be reduced by reducing oil feed pressure [15,16]. The reduction is at least partly explained by observations of the film in a journal bearing with a transparent bush which show that when the oil supply is restricted, cavitation develops and the film area is reduced [17,18,19].…”

Component level study of an actively lubricated LEG Tilting Pad Bearing: Theory and experiment

“…Under such configuration, the injection nozzles located in the tilting pad surface are replaced by the leading edge groove, as the method to provide controllable pressurized oil supply to the bearing clearance. The leading edge groove has already been studied in terms of its benefits considering reduced oil consumption and reduced bearing losses, when compared to other lubrication methods [17,18,19,20]. The results obtained from the mathematical model for the proposed active bearing design validated the initial concept.…”

Thermoelastohydrodynamic Behavior of a Journal Bearing with Turbulent Flow

“…The relative displacement of the fluid-structure interfaces in the fluid domain is consistent with that of the solid domain. The film thickness is defined as the distance between the rotor-lubricant interface and the bearing-lubricant interface, including both rigid and elastic deformations between the two bearing surfaces as: (4) where h is film thickness, C is radial clearance of the bearing system, Δh is relative rigid displacement of the two bearing surfaces and δ is total elastic deformation of the two bearing surfaces.…”

“…FEM codes were usually used separately to calculate bearing deformations [2,3]. On the other hand, CFD codes were applied to investigate flow phenomena in the lubricating oil and water or in the regions surrounding the bearing, both in journal [4,5] and thrust bearings [6]. Reliable theoretical prediction of bearing properties requires simultaneous consideration of interacting phenomena such as lubricant flow, heat transfer and the distortion of bearing elements.…”