Dynamic characteristics of compensated hydrostatic thrust pad bearing subjected to external transverse magnetic field

This article presents finite element analysis to evaluate the performance of a compensated hydrostatic circular thrust pad bearing in the presence of a magnetic field. The influence of the magnetic field on the flow of an electrically conducting lubricant is expressed by incorporating the Lorentz force in the momentum equation, described by Maxwell equations and Ohm's law. The modified Reynolds equation has been derived for a lubricant blended with long-chain polymer additives flowing in the presence of a transverse magnetic field. The Stokes couple stress theory has been used to describe effect of such additives on lubricant rheology. A source code has been developed in MATLAB to solve the modified Reynolds equation coupled with restrictor flow equations using the finite element method. The performance characteristics of the bearing system are evaluated in terms of pocket pressure, load-carrying capacity, lubricant flow rate, fluid film stiffness and damping coefficient. Comparative studies have been carried out for orifice and capillary compensated bearings. The limiting cases of the modified Reynolds equation yield performance characteristics of specific lubricants such as electrically conducting couple stress lubricant, couple stress lubricant, electrically conducting lubricant and Newtonian lubricant. It is noticed that the load-carrying capacity, fluid film stiffness and damping capabilities of the bearing get enhanced quite substantially in the presence of couple stress additives and a magnetic field.