Design of actively-controlled oil lubrication to reduce rotor-bearing-foundation coupled vibrations - theory & experiment

This paper gives theoretical and experimental contributions to the field of tribotronics, linking i) tribology of fluid film bearings, ii) flexible rotor and flexible foundation dynamics, iii) sensing systems, iv) fluid power and hydraulic actuator dynamics, and v) control theory in a holistic way. Based on a multi-physical modelling approach, a mathematical model (digital twin) is derived coupling the subsystems from i) till v). The digital twin is employed to design and optimize the feedback control system of an actively-controlled tilting pad journal bearing with the aim of attenuating vibration levels of the rotor-bearing-foundation system. The feedback control system is experimentally implemented and tested on a test rig. Significant reduction of the rotor-bearing-foundation vibrations is achieved in the frequency range of 20 until 250  Hz. Very good agreement between theory and experiment is achieved at the low rotor angular velocity used. The theoretical and experimental outcomes of the paper suggest that vi) the thermal domain needs to be included in the multi-physical modelling approach to accurately represent the bearing properties under thermoelastohydrodynamic conditions and expand the theoretical and experimental approaches to higher angular velocities.