STATIC AND DYNAMIUMALYSIS OF CIRCULAR AND NONCIRCULAR BEARINGS IN LAMINAR AND SUPERLAMINAR REGIMES

Abstract

Modern large turbogenerators use large size bearings (500 mm or more in diameter) to support heavy rotor loads at high speeds. In many industrial applications, process fluids of low kinematic viscosity are used as lubricants in bearings. These bearings invariably run either in transient or turbulent flow regime due to large journal surface velocity and/or low kinematic viscosity of lubricants. Reynolds numbers upto 7500 have been reported in literature for turbogenerator bearings. In future, still higher Reynolds numbers are expected with the trend for more economical power generation requiring larger machines. To predict the characteristics of the bearings in the turbulent regime for their realistic design, the effect of turbulence must be determined accurately. In the existing literature, for the study of turbulence effects, the modified Reynolds equation has been solved numeri-cally using the linearized turbulence theories. Although the results of the linearized turbulence theories can be consider-ed to be practically acceptable at low Reynolds numbers and upto moderate eccentricities, the bearing performance characteristics at high Reynolds numbers and large eccentrici-ties can be predicted accurately only when the nonlinear theories are employed