Active thrust fluid-film bearings: Theoretical and experimental studies

Abstract

Research in the field of active fluid-film bearing has been recently getting more and more attention, integration of control systems becoming one of the most promising means of enhancement of rotor-bearing nodes' characteristics. It has been determined that the vast majority of papers published on active fluid-film bearing only consider radial bearings, and very few focus on thrust bearings. This lack of attention along with the obvious necessity to fill the said gap has triggered the present research. In cases of rotor machines that experience extensive axial loading due to various reasons, e.g. various turbine engines (aero and spacecraft) and hydraulic pumps (crude oil extraction facilities), such research could prove the feasibility of application of a control system to significantly increase the performance of the whole machine. Moreover, extensive wear during start up and shut down could be eliminated by means of rotor position control, thus life time of a rotor-bearing system could be significantly increased. The present paper features a complex mathematical model of an active thrust fluid-film bearing with a central feeding orifice, a developed test rig designed to verify the presented mathematical model allowing a series of numerical tests to be carried out. Numerical studies focus on the hypothesis of a possibility to use active control in thrust bearings to decrease power loss due to friction and extensive axial vibrations by means of identification of an energy efficient area of axial gaps based on the lubrication regime and its maintenance by means of application of controlled lubrication principles.

Evaluation of energy efficiency of thrust hybrid bearings with active control of lubrication regime

“…Mathematical modelling of the ATHB is hence based on equations of hydrodynamic lubrication theory for the fluid film, equation of motion for the rotor-bearing dynamic system and control theory equations for the PID controller and an actuator. Modelling and verification of the mathematical model and experimental testing of the developed object of study has been done in [13]. The present paper, in the meantime, is going to focus solely on energy efficiency parameters of the developed object of study.…”

“…The present paper, in the meantime, is going to focus solely on energy efficiency parameters of the developed object of study. The hypothesis expressed in [13] stated that there is a specific area within the axial gap of a THB where friction and, consequently, power loss due to friction tend to their minimum values, and this axial gap shall be referred to as energy efficient. Objective of [13] was to propose a way of maintenance of this energy efficient position by means of active control.…”

Observer-Based Control of Tilting-Pad Thrust Bearings

“…Shaft-vibration amplitudes were reduced by between 11 and 18% depending on the shaft speed, and good agreement was obtained with a mathematical model. Further work has been pursued on hydrodynamic, hydrostatic, aerostatic and magnetic journal bearings by many authors [6][7][8] examining the dynamic performance of such contacts, and Santos presents a useful review [9].…”

Model-Based Design Approach to Improve Performance Characteristics of Hydrostatic Bearing Using Multivariable Optimization

“…A prototype is developed for the active bearing where the clearance gap is controlled through high-speed solenoid valves but deficiency arises because it is used for light load applications [10]. The rotor bearing node's characteristics are improved by the integration of control techniques for thrust fluid bearings [11]. The eddy current sensors are used to monitor the gap of the hydrostatic bearing so that the load-carrying capacity can be improved by activating the hydrostatic support but there is deficiency in the low resolution of the eddy current sensors [12].…”