Theoretical Evaluation of the Operational Characteristics in a Large Thrust Bearing

Abstract

In this paper the non-dimensional load, volumetric flow rate, energy flux, oil film temperature and power loss parameters of a tilting-pad thrust bearing are formulated. The objective of the paper is to determine the novel non dimensional thermal, volumetric and power loss parameters in addition to the load and energy flux parameters of the bearing. The computation is done by formulating and numerically solving for the oil film thickness, two dimensional Reynolds', Vogel-Cameron viscosity-temperature relationship and energy equations at the different nodes of the oil film using a finite difference procedure. The planar film shape polynomial ensures the accuracy of the slider bearing shape and pressure distribution. The numerical procedure evaluates the value of 'a' at which the load is maximum. The variation of the bearing centre of pressure with respect to the corresponding values of 'a' is studied. From the fluid film temperature equation the rise in bearing temperature corresponding to the range of 'a' values is determined. The oil film temperature distribution results are found satisfactory in terms of computer time and convergence criteria. The accuracy of the results is validated in the variation of the load and thermal contours. A mesh independence test is conducted using three meshes of different sizes. The mesh independent solution and convergence is obtained for the smallest mesh that also reduces simulation run time. This data and analysis serves as an input to determine the dynamic stiffness and damping coefficients. It includes the scope to develop a design method for safe operation of the bearing at any speeds in vertical hydro-electric rotors.