Analysis of hole entry hybrid journal bearing operated with ER fluids

Abstract

The static and dynamic performance of journal bearings depends upon the newlinebehaviour of lubricants in the clearance space of journal and bearing. The newlineElectrorheological (ER) fluid has emerged as an effective lubricant to enhance the newlineperformance of journal bearings. ER fluid is a smart fluid in which the viscosity of newlinethe fluid changes as a result of imposition of electrical field. It is expected that the newlineER fluid will enhance the journal bearing performance. Journal bearings operated newlinewith ER fluids, couple-stress lubricants, micropolar lubricants, power-law newlinelubricants are discussed along with the generally used space lubricants in the newlinepresent thesis. Generally, hydrostatic and hydrodynamic journal bearings are used newlinein rotating mechanical assemblies. In journal bearing, surfaces of the journal and newlinebearing are separated by a pressurized film of lubricant. The lubricant film pressure newlinecan be generated through the relative motion of the surfaces of journal and bearing newlineor through the externally pressurised fluid. The first of these is known as newlinehydrodynamic action and second as hydrostatic action. Hybrid journal bearing newlinecombines the advantages of hydrostatic and hydrodynamic journal bearing. The newlineperformance of hybrid journal bearing operated with ER fluid is analysed in the newlinepresent work. Finite Element Method is used to solve the Reynolds equation newlinegoverning the flow of ER fluids in the bearing clearance space. The static and newlinedynamic performance characteristics such as minimum fluid film thickness, newlinemaximum pressure, fluid flow rate, damping coefficients, stiffness coefficients etc. newlineare analysed numerically. The external applied radial load, journal rotational speed, newlineapparent dynamic viscosity of the lubricant are the input parameters used for the newlineanalysis. An effort is made to develop the design data for ER fluid lubricated hybrid newlinejournal bearing. Neural network approach is used for the journal bearing newlineperformance predictions newline