EFFECT OF POLYMER ON FLOW IN JOURNAL BEARINGS

The flow of single and multi-grade lubricants between eccentric cylinders was studied experimentally to assess the effect of polymer additives. Azimuthal velocity profiles were measured in steady flow using laser Doppler velocimetry. The addition of polymer significantly decreases the size of a counter-rotating eddy that forms adjacent to the stationary wall in the large gap region. Film thickness in a dynamically loaded journal bearing was also measured using eddy current probes. Viscoelasticity associated with polymer additives did not influence minimum film thickness or attitude angle under loading conditions characteristic of an engine cycle. Results in both steady and unsteady flows are at least qualitatively consistent with predictions of the upper convected Maxwell model.