Application of tilting-pad bearings in the design of large output turbines

Modern steam turbines for electric power utilities have reached the output of 1000 MW per unit. It causes the need for an increase in shaft diameters and application of special tilting-pad journal bearings. The tilting-pad journal bearings are one of the options as they have very good hydrodynamic stability at high speed and are less sensitive to load direction and shaft misalignment. They allow for minimizing the oil flow too. In case of large output turbines, large diameter of heavy rotors the number of pads is restricted to three. The reliable design of journal bearings for responsible turbines is assured by calculation and analysis of static and dynamic characteristics of bearing. These characteristics can be determined from the oil film pressure and temperature distributions. The paper describes the possibilities of the application in large output turbines of some tilting-pad bearings. Static characteristics of these bearings can be obtained from the solution of Reynolds, energy, geometry and viscosity equations. Numerical method, assumption of incompressible lubricant, the laminar and adiabatic flow of oil in the bearing gap of finite length bearing and static equilibrium position of journal have been assumed.