PERFORMANCE EVALUATION OF A TILTING PAD HYDRODYNAMIC JOURNAL BEARING

Abstract

Bearings are an integral part of our machinery system. They aid in transmission by supporting rotating machinery parts. Tons of loads of rotating machinery are supported in our hydropower plant. Due to the 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 their characteristics as per the operating speed and applied load. Therefore these bearings are called self-optimized bearings. Correctly operating tilting pad 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 are mounted oil 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 carry fresh oil into the pad area. Tilting moment due to fluid film pressure cause 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 shoe and journal is formed according to the supporting loads and speeds. This report presents the static and dynamic performance characteristics for a 4 pad and 5 pad tilting pad journal bearing in both the load on pad and load between pad configurations over different loads and speeds. Tilting pad journal bearing geometry is complex and load and tilt angle has nonlinear relationship with load. Therefore, a FEM program in MATLAB is developed to solve the Reynolds equation. To evaluate tilt angle and journal center equilibrium position. Newton Rapshon iterative method is applied. From the MATLAB program, maximum fluid film pressure, minimum fluid film thickness, load carrying capacity, tilt angles, eccentricity of journal, stiffness coefficients and damping coefficients are calculated. These results of four pad tilting pad journal bearing with load between pad configurations are validated with published research paper.