Year: 2013
Type: dissertation
Abstract: Since 1960s, Squeeze Film Dampers (SFDs) have been widely applied to rotating machinery, including ground-based turbines, compressors and aero-engines.The reason behind the popularity of SFDs is their ability to attenuate system vibrations and improve system stability.Many efforts have been made to understand their properties at both component and system level.However, the discrepancies between predictions and experiments and the deficiencies of theoretical models to satisfy industrial requirements still exist in those studies.For the analysis of SFDs at component level, the major assumptions in the previous studies include open-end with full leakage, perfect seals with no leakage and ideal supply/discharge conditions.These presumptions fail to give reliable predictions of damping capacities in industrial applications.Another limitation of the component level analysis in the previous work is the constraint on the journal motion, which requires the journal to precess synchronously within either circular centered orbits or off-centered circular orbits having small amplitude.These kinds of presumptions prevent accurate predictions for the performances of SFDs in practical rotating systems.Besides the limitations of the component level analysis, the methods for predictions at the system level fail to handle complicated operating conditions for the practical rotating machinery with SFDs.The force coefficient method using traditional iteration procedures is sensitive to the variation of operating conditions and can not deal with rotating systems having excessive dynamic loads.Additionally, when using the direct force methods, most of the past studies consider simple rotating systems on SFDs, and all of them apply extensively ii Abstract iii the full end-leakage model.To meet the needs of industrial applications with SFDs, this work focuses on considering realistic damper configurations and improving the efficiency and robustness of prediction tools for rotordynamic analysis.One of the common sealing conditions, the piston ring seals, is investigated with two different supply/discharge methods, the central groove and direct holes.The finite difference method is used to obtain the pressure distribution and First and foremost, I am deeply grateful to the Rotating Machinery and Controls (ROMAC) laboratory for the support throughout this process.I have learned a lot from this great opportunity that was given to me.
DOI: 10.18130/v3t79k
Author: Feng He
Institution: University of Virginia
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W4242640888