Active Control of High­-Speed Flexible Rotors on Controllable Tilting­-Pad Journal Bearings : Theory and Experiment

Abstract: A common choice of bearing for industrial applications such as turbomachinery and rotating compressors is the Tilting-Pad Journal Bearing (TPJB) due to its excellent stability properties. TPJB's are however limited by the reduction of damping in the fluid film at high velocities. In order to overcome this, the Active Tilting-Pad Journal Bearing (ATPJB) has been developed. By adding the possibility of high-pressure radial oil injection through servo-valves which can be controlled via a feedback-loop control system, the classically purely mechanical TPJB becomes a mechatronic device called ATPJB.  The objective of this project is to conduct an experimental evaluation of the dynamical behavior of the ATPJB test rig located at the Technical University of Denmark, use the experimental results to modify the previously developed dynamical model which is used for the calculation of a model-based control system. The control system is to be implemented and experimentally validated at high velocities. Improvements made to the test rig in order to achieve high velocities have been documented and described in this work. The mathematical modeling of the individual components, reduction methods, and the global system assembly is covered with an extensive overview. Parameters of the model have been made frequency dependant in order to have an accurate model, resulting in good agreement with experimental data over a wider operational range. With the implemented Linear Quadratic Gaussian controller it is shown that ATPJB has extended operational range compared to TPJB and shows reduction of vibrations over rotational speeds spanning from 1000 RPM to 10,000 RPM. The ATPJB-technology, as it is implemented in this project, does not improve frictional losses in the system. It is argued that the added sensing and actuating systems inherited in the ATPJB technology make the technology highly suitable for the ideas of Industry 4.0 and also allows for the implementation of Early Fault Diagnosis which gives an economical incitement to invest in ATPJB-technology.