An electrorheological hydrostatic journal bearing for controlling rotor vibration

The objective of this work is to study the dynamic behavior of a rotor supported by a new hydrostatic journal bearing, and fed with a negative electrorheological (NER) fluid. The hydrostatic bearing consists of four hydrostatic bearing flat pads fed by capillary restrictors. An ER fluid consists of a suspension of micron-sized particles dispersed in a dielectric liquid. A negative electrorheological (NER) fluid is a Newtonian fluid with a viscosity which decreases when an electric field is applied, and which can restore its property when the field is removed. A reversible change in viscosity occurs in milliseconds with the electric field applied. Therefore, these fluids are suitable for the real-time control of vibration and vibration damping. A linear modeling was performed using numerical methods in order to investigate the effect of negative electrorheological fluids, recess pressure and static eccentricity ratio on carrying load capacity, flow, and the equivalent dynamic characteristics (stiffness, damping, damping factor) of a new NER hydrostatic journal bearing. In a first step, the flow, equivalent stiffness and damping and damping factor is studied according to the pressure ratio, for different electric field values at the point of operation. In a second step, the variation of carrying load capacity and equivalent stiffness and damping is studied according to the static eccentric ratio, for different electric field values. In a third step, an application study of an NER hydrostatic journal bearing based on linear theory is presented in order to reduce or suppresses the imbalance-induced vibration or the force transmitted to the base. The discussion of results includes some thoughts on future trends. (C) 2007 Elsevier Ltd. All rights reserved.