| Summary: | This thesis describes the results of a combined theoretical and experimental investigation into the thermohydrodynamic behaviour of a twin axial groove cylindrical bore journal bearing. The theoretical work involved the solution or Reynolds equation and energy equation where appropriate in two dimensions using the finite element method. Several numerical studies for isothermal conditions were then carried out to examine the film incompleteness effects on the bearing global behaviour and which demonstrated the considerable sensitivity with respect to loading vector. Concurrently, an experimental journal bearing test rig was developed for the required experiments. It has a bush diameter of 75.3mm and uses two shafts to give nominal clearance ratios of 0.002 and 0.004. The bush was comprehensively instrumented with thermocouples to give detailed information of bearing and white metal temperatures. Experiments were conducted successfully to obtain lubricant flow rate, bush torque reaction, journal load capacity and journal position for varying shaft speed and loading direction, and this demonstrated experimentally the sensitivity with respect to load vector and provided boundary conditions for thermal models. Two thermal models were developed and these suggested that, at a prescribed eccentricity ratio, a very significant load increase can occur (threefold) for a small change in loading direction. Additionally, predicted side flow is very load direction dependent while bush torque reaction is not. These predicted trends are confirmed by experimental observation and it was found that a rigorous thermohydrodynamic model gave the most close agreement between absolute measured and predicted bearing performance.
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