INFLUENCE OF PIVOT STIFFNESS ON THE PERFORMANCE OF TILTING PAD - HYDRODYNAMIC JOURNAL BEARINGS

Abstract

Bearings are an integral part of any machinery system. They helps in transmission by supporting rotating machinery parts. Tons of loads of rotating machinery are supported in our hydropower plant. Due to the ever growing demand of power, minimization of the frictional power consumption in bearing is important. Tilting pad journal bearings are active bearings which can support the load with minimum friction power consumption and also provide good stability to the system. These bearings have the ability to modify the characteristics as per the operating speed and applied load. Therefore these bearings are called self optimized bearings. Correctly operating tilting pad journal bearing has almost negligible maintenance and repairing. Because use of these bearings minimizes the wear between bearing pad and journal. - In tilting pad journal bearing, shoes or pads mounted on pivots. These pads are nothing but the bearings sectors supporting the loads together. When the bearing is in operation, the rotating part of the bearing carries fresh oil in to the pad area. Tilting moment due to fluid film pressure causes the pad to tilt about the pivot, building a wedge of pressurized fluid between the shoe and the journal surface. Due to tilt an optimum wedge of oil film between and journal is formed according to the supporting loads and speeds. The study presents the influence of pivot stiffness on the performance of tilting pad journal bearing. This report presents influence of pivot stiffness on the static and dynamic performance for a 4 pad and 5 pad tilting pad bearing in load between pad configuration over a variety of different loads and speeds. Finite Element Method is used to solve the Reynolds equation and then for found the static and dynamic parameters. Newton Rapshon method is - used for the convergence. In order to do analysis a MATLAB code has been developed to solve Reynolds Lubrication equation to get the pressure distribution in the fluid film of tilting pad journal bearing. From the analysis of bearing some main static characteristics like maximum pressure, minimum fluid film thickness, eccentricity of journal, stiffness coefficients and damping coefficients are calculated. The results have been validated with a published research paper. Permissible amount of deviation has been found between the results.