On-off control of HSFD supported rotors

This paper describes the theoretical and experimental application of on-off control to the Hybrid Squeeze Film Dampers (wHSFDs). Two modes of operation are possible with an HSFD: a long damper mode with larger damping capability and a larger transmitted force, and a short damper mode with a smaller damping capability and a smaller force transmitted. The capabilities of HSFDs are described in detail as well as methods of designing the HSFD for the active control of rotors. The application of on-off control is presented as a means of passing critical speeds in the long damper mode, and alternatively sustaining operation at the short damper mode. Experimental application of the on-off control to a multi-mode rotor is presented. Excellent agreement between the theoretical and experimental results is obtained as well as evidence of the robustness of the on-off control, which is one of the best control algorithms for the HSFD (if designed properly), except for its disturbance rejection capabilities.