Effects of two lobe wave squeeze film damper in the support of an unbalanced rigid rotor

A possible improvement of the performances of squeeze film damper (SFD) for supporting the rotors of high-speed turbomachinery has been sought adopting a two lobe, wave (2LW) geometry of the bearing bore. A statically unbalanced, symmetrical, rigid rotor supported with 2LW-SFD has been theoretically examined through numerical continuation, assuming laminar, isoviscous oil flow within the damping film and incomplete centering action of the retainer springs mounted parallel to the film. Despite nonlinearity which still affects the system, the obtained results highlight the potential of the unconventional geometry as a mean for a possible reduction of the typical drawbacks in the response with conventional SFD, mainly consisting in undesired whirling motions with too large journal orbits and/or nonsynchronous character, so as to assure more safe conditions for the rotor operation. Yet, further theoretical and experimental investigation is desirable in order to confirm such an outcome.