Influence of the bushing geometry on the thermohydrodynamic performance of a misaligned journal bearing

Often journal bearings have to support shafts that run misaligned into the bushing bore because of the combined effect of elastic deformations and manufacturing tolerances. In such cases, the thermo-hydrodynamic behaviour of the bearing needs to be investigated in detail in order to ensure the safe operation of the device, or, in other words, to avoid asperities contact. The difficulties to model the thermal phenomena comprise one of the main reasons for the limited contribution of theoretical models to the designing efforts. In this article an accurate thermo-hydrodynamic simulation of journal bearings operating under misalignment conditions is introduced at first. Then, the computed film thickness, pressure and temperature distribution, as well as the friction coefficient are shown for several variations of hour-glass profiled bearings operating under a misalignment of up to 5. From the results shown it can be concluded that the load-carrying capacity of journal bearings can be greatly enhanced if a properly selected hourglass design is applied. The results show further that a three-dimensional thermo-hydrodynamic analysis, as the one shown here, should always be carried out in order to verify the bushing design.