Theoretical and experimental studies of the effect of clearance and geometry in hydrodynamic journal bearings

This study is concerned with oil lubricated, hydrodynamic journal bearings. A test rig was developed which allowed measurements of film pressure, film thickness and journal surface temperature, from the rotating journal. In addition to this it allowed the more commonly measured variables of bearing oil flow and some characteristic bearing temperatures to be friction, monitored. It has been shown that an optimum clearance exists, which maximizes the minimum film thickness. This experimentally measured optimum has been compared with various theoretical estimates, with varying degrees of correlation. An optimum bearing length has been observed which minimizes the bearing friction. This was not predicted by any theoretical results, but a reason for its existence has been suggested. Small errors in bearing geometry were experimentally observedâ to give rise to large distortions in the film pressure A simple theoretical model for an infinitely long non-geometric profiles. bearing was constructed and measured trends. â º found to support the experimentally The infrequently observed phenomenon of tensile stresses was . measured in the oil film under certain stresses, at times of the order of 100lbf/in. , have been accounted conditåons. These tensile for by consideration of the In order to permit the parameters it was necessary A film thickness inductance nature of liquids under tension. _ measurement of journal bearing to develop certain instrumentation. transducer of low temperature and pressure sensitivity was developed. In addition to this a pressure transducer was constructed and its frequency response characteristics were evaluated in conjunction with various entrance tubes. This particular study highlighted the region of applicability of the ' available theoretical models for predicting pressure transducer/ tubing response. -