PERFORMANCE ANALYSIS OF A TILTING .PAD HYDRODYNAMIC JOURNAL BEARING OPERATING IN TURBULENT REGIME

Abstract

Filling pad journal bearings are most commonly used in rotating machinery in present days due to their inherent stability at high speed and light load. In this age of evolution and the increasing demand in the efficiency of machinery, it has become necessary to run the machinery at high speed. The bearing also has its own importance in the satisfactory functioning of the machinery in the form of reduction in wear between two parts in relative motion. In rotating machinery, the hydrodynamic journal bearing is employed to fulfill the requirement of the lubrication between rotor and the outer casing. But it higher rotor speed it becomes unstable due to oil whirl in the clearance space of the bearing. To overcome this adverse effect of the oil whirl oil the rotor stability, tilting pad journal bearings are employed. In the present work the performance of tilting pad hydrodynamic journal bearing has been analyzed for turbulent operating conditions. For the analysis the linearized turbulent Reynolds equation derived by Constantinescu is modeled in FEM using a Galerkin approach in order to calculate the fluid film pressure distribution in the bearing clearance space. The Newton- Raphson method is used to calculate the journal center position and the tilt angle at equilibrium. The finite element mesh is generated in the Matlab taking 100 nodes for every pad. The entire solution procedure for the analysis of the performance characteristics of the tilting pad hydrodynamic journal bearing is transformed into the source code in the Matlab. The numerically simulated results for the behavior of 4-pad and 5-pad tilting pad bearing under LOP and 1,I3P loading arrangements are presented in the form of static performance characteristics such as fluid film pressure distribution, fluid film thickness in the bearing clearance space, maximum fluid film pressure, minimum fluid film thickness and tilt angles of the pad as well as the dynamic performance characteristics such as fluid film stiffness and damping coefficients.