THERMOHYDRODYNAMIC ANALYSIS OF TILTING PAD THRUST BEARING

Abstract

Bearing is one of the one of the main vital components in any machinery. So it should be properly designed. Its design aspects are depending on its performance in various conditions. Generally analysis of bearing is fully depends on hydrodynamic lubrication analysis keeping fluid viscosity constant. But if the temperature of the fluid film changer then the viscosity also changes and then came the thermal effects on bearing performance and bearing design. A thermo-hydrodynamic analysis (THD) of a bearing refers to a realistic solution of the Reynolds equation in which the viscosity field is predicted based on the computation of temperature obtained from the conservation of energy. Prediction of a bearing's performance based on a THD analysis generally requires simultaneous solution of several numerical partial differential equations in either two or three dimensions so that the temperature (and therefore viscosity) field is treated as individual points along the direction of motion, across the film, and if necessary in the axial direction where leakage takes place. With the increase in the operating speed the design of these bearings are reaching a limit whereby the steady state performance does not match the performance predicted by the predicted theories. This is typically encountered when the bearing operating conditions are in the turbulent regime. With the continuing drive for greater operating speeds for increased efficiency of high performance machines, the application range of the conventional design is also reaching a limit. Recent developments in Tilting Pad Thrust bearings design have addressed both performance and extension of the application range. These efforts have concentrated on minimizing power loss and reducing oil flow rates, while at the same time decreasing operating pad temperature which is more important in slider bearings which consume more power of the bearing system. The main theme of this project is THD analysis of Tilting Pad Thrust bearings. In order to analysis a MATLAB code has been developed to solve Reynolds Lubrication equation and energy equation to get the pressure and temperature distribution in the fluid film of the Tilting Pad Thrust Bearing. From the THD analysis of the bearing some main static characteristics like maximum pressure, maximum temperature, load carrying capacity and centre of pressure can also be calculated. The result shows that there is significant amount of change in Pressure distribution, maximum pressure and load carrying capacity that has been calculated in simple Hydrodynamic lubrication. The results have been validated with a published research paper. Permissible amount of deviation has been found between the results. In this report only the static characteristics of the Tilting Pad Thrust Bearing has been calculated. No dynamic properties have been considered in this dissertation