Fuzzy proportional-integral-derivative control of an overhang rotor with double discs based on the active tilting pad journal bearing

An overhang rotor with two discs supported by a couple of tilting-pad journal bearings is investigated in this paper. The active lubrication based on injecting pressurized oil into the bearing gap through orifices machined in the bearing sliding surface is utilized to suppress the shaft vibrations. A fuzzy proportional-integral-derivative (PID) controller is designed for the active lubrication to adjust the rotor-bearing equilibrium position. The finite difference method is applied to solve the pressure distribution on each tilting pad surface of the active lubricated system. Numerical simulation and experiment results show that the actively lubricated system presents effective vibration reduction of unbalance response of a flexible rotor and the fuzzy PID controller exhibits good performance. Finally the superiorities in employing the active lubricated system with regard to extending the stable operational speed ranges and manage to put off the instabilities (whirl) of the rotor-bearing system are also investigated, and clearly illustrate one of its most promising applications.