Numerical and Experimental Studies of Axial Stability of Rotors on Thrust Fluid-Film Bearings with Active Control

The present paper explores a possibility of the application of thrust fluid-film bearings with active control of rotor axial position control to enhance rotor stability and increase energy efficiency of rotor-bearing systems. A mathematical model has been developed that incorporates a detailed mathematical description of fluid flow in the bearing, a rotor-bearing dynamic model based on a linearization approach that helps to identify dynamic coefficients of the fluid film and a control system model based on a model of a servovalve, that acts as an actuator in the system, and a PID-controller. By means of controlling the flow rate through the servovalve, it is possible to adjust the supply pressure of the fluid to the area of friction in the bearing thus controlling the bearing reaction force and, consequently, the rotor's axial position. This would help one to enhance the rotor stability by means of maintaining a constant axial gap and increase energy efficiency by means of maintaining the value of the axial gap within the range of gap heights where the least power loss could be achieved due to friction. The present paper also features a description of the developed test rig designed to prove the theoretically substantiated hypothesis possibility and initial experimental results.