Eickhoff, Markus (2024)
Analysis and Optimization of Single-Pad and Multi-Pad Air Foil Thrust Bearings.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00027789
Dissertation, Erstveröffentlichung, Verlagsversion
Kurzbeschreibung (Abstract)
Air foil bearings are a type of compliant hydrodynamic bearing that feature a reliable, low-maintenance, and ecological machine element for high-speed turbomachinery. Due to the utilization of surrounding air or other gases as a lubricant, they can be used in oil-free machines. When compared against rigid air bearings, they present a low-cost and robust alternative. The analysis and optimization of air foil thrust bearings is challenging owing to the multiphysicality of thermodynamic, elastomechanic and hydrodynamic equations that have to be considered as well as their coupling in detailed numerical models. In this thesis, bump foil thrust bearings, consisting of a base plate, corrugated bump foils and smooth top foils are examined. They can be categorized in two different design types: firstly, a multi-foil design consisting of several independent bearing pads, and secondly, a single-foil design comprising several independent bump foils, but a single, annular top foil. The differences in the modeling approaches are illustrated. It is concluded that single-foil bearing analysis is only possible when the real foil geometry and top foil coating wear are included in the analysis. Furthermore, a full bearing model accounting for each individual pad of the multi-foil design in the case of misalignment is compared against a reduced approach using symmetry conditions. The thermal management of foil thrust bearings turns out to be one of the prime tasks for the optimization of load capacity and losses. The thermal bending of the runner disk that is caused by axial temperature gradients is shown to have a significant effect on bearing performance. The most prominent solution is the application of a forced cooling flow underneath the top foil. However, this reduces overall machine efficiency. Apart from this straightforward method, choosing an alternative foil material with a high thermal conductivity and compensating mechanisms based on centrifugal effects are presented here.
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2024 | ||||
Autor(en): | Eickhoff, Markus | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Analysis and Optimization of Single-Pad and Multi-Pad Air Foil Thrust Bearings | ||||
Sprache: | Englisch | ||||
Referenten: | Schweizer, Prof. Dr. Bernhard ; Becker, Prof. Dr. Wilfried | ||||
Publikationsjahr: | 19 September 2024 | ||||
Ort: | Darmstadt | ||||
Kollation: | 135 Seiten in verschiedenen Zählungen | ||||
Datum der mündlichen Prüfung: | 17 Juli 2024 | ||||
DOI: | 10.26083/tuprints-00027789 | ||||
URL / URN: | https://tuprints.ulb.tu-darmstadt.de/27789 | ||||
Kurzbeschreibung (Abstract): | Air foil bearings are a type of compliant hydrodynamic bearing that feature a reliable, low-maintenance, and ecological machine element for high-speed turbomachinery. Due to the utilization of surrounding air or other gases as a lubricant, they can be used in oil-free machines. When compared against rigid air bearings, they present a low-cost and robust alternative. The analysis and optimization of air foil thrust bearings is challenging owing to the multiphysicality of thermodynamic, elastomechanic and hydrodynamic equations that have to be considered as well as their coupling in detailed numerical models. In this thesis, bump foil thrust bearings, consisting of a base plate, corrugated bump foils and smooth top foils are examined. They can be categorized in two different design types: firstly, a multi-foil design consisting of several independent bearing pads, and secondly, a single-foil design comprising several independent bump foils, but a single, annular top foil. The differences in the modeling approaches are illustrated. It is concluded that single-foil bearing analysis is only possible when the real foil geometry and top foil coating wear are included in the analysis. Furthermore, a full bearing model accounting for each individual pad of the multi-foil design in the case of misalignment is compared against a reduced approach using symmetry conditions. The thermal management of foil thrust bearings turns out to be one of the prime tasks for the optimization of load capacity and losses. The thermal bending of the runner disk that is caused by axial temperature gradients is shown to have a significant effect on bearing performance. The most prominent solution is the application of a forced cooling flow underneath the top foil. However, this reduces overall machine efficiency. Apart from this straightforward method, choosing an alternative foil material with a high thermal conductivity and compensating mechanisms based on centrifugal effects are presented here. |
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Status: | Verlagsversion | ||||
URN: | urn:nbn:de:tuda-tuprints-277894 | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften und Maschinenbau | ||||
Fachbereich(e)/-gebiet(e): | 16 Fachbereich Maschinenbau 16 Fachbereich Maschinenbau > Institut für Angewandte Dynamik (AD) 16 Fachbereich Maschinenbau > Institut für Angewandte Dynamik (AD) > Modellierung von Öl- und Luftlagern für hochdrehende Rotoren |
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Hinterlegungsdatum: | 19 Sep 2024 08:19 | ||||
Letzte Änderung: | 20 Sep 2024 08:22 | ||||
PPN: | |||||
Referenten: | Schweizer, Prof. Dr. Bernhard ; Becker, Prof. Dr. Wilfried | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 17 Juli 2024 | ||||
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