Studio e sviluppo di un cuscino di smorzamento a film d'olio per compressori centrifughi

The present thesis work has been developed during the internship held at the Nuovo Pignone S.p.A, company located in Florence. It consisted in the study and following optimization of a Squeeze Film Damper Bearing designed in the company in the 70's and installed only on a single centrifugal compressor. The Squeeze Film Damper Bearing is a type of bearing usually installed in series with a conventional journal bearing to attenuate vibration amplitudes and increase stability of rotors. The study started with an overview of the state of art of the squeeze film damper design and all the rotordynamics tools necessary to the study and analysis of these devices integrated in the rotor-system assembly. From a rotordynamic viewpoint the Squeeze Film Damper was studied as follows. The ideal cases of a rigid symmetric rotor and a Jeffcott symmetric rotor were analyzed to highlight the effect of the Squeeze Film Damper using simplified analytical tools. Finally the interaction of the Squeeze Film Damper Bearings with a real rotor (a test rotor developed for company internal testing) was studied using a specific rotordynamic software From a structural viewpoint the original design of the Squeeze Film Damper Bearing was checked through Finite Element Analysis to evaluate the characteristics of the critical elements in terms of dynamic stiffness and fatigue. Finally an optimization of the main design parameters governing the response of the system, in particular stiffness and damping, was made to increase the impact of the device in reducing vibration amplitudes and increase stability. Novel solutions of critical elements were proposed and analyzed to meet guidelines coming out from the rotordynamic analysis