Dynamic modelling and analysis of vertical machines
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Since Sweden’s hydropower plants are getting old and operating conditions have changed, there is a need for simulation tools to predict the functionality, durability and needs for maintenance. Also for breakdowns and major revisions, there is a benefit if dynamical problems could be predicted through simulations. The important parts in the modelling of hydropower machines are the interconnections (Bearings, Generator, Runner). Therefore, accurate and fast models are preferred to describe the interconnections and implement to the finite element model of the rotor. Since hydropower machines are oriented ertically the bearing coefficients needs to be described dynamically. This is due to the fact that vertical machines has no stationary operating point.In paper A simulations of a hydropower machine that suffered from resonance problems were performed. To reduce vibrations, a new type of viscoelastic supports was implemented between the supporting structure and bearing bracket. It was shown through simulations that this support would reduce the vibration levels and reduce the probability of resonance problems occurring when running at operating speed. In paper B the effect of cross-coupling bearing terms was investigated, commonly the cross-coupling terms are neglected since they are small in comparison to the radial components. This is shown to be true for some load cases, but if studying a vertical machine the load angle will change dynamically and for some load angles the cross-coupling terms cannot be neglected. Experiments on a vertical test rig with tilting pad bearings also agree well with the simulations performed. Since the tilting pad bearings in vertical machines introduce periodic coefficients in the bearing, studies in paper C shows that this periodic excitation can cause increased vibrations for certain operating conditions.
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2016.
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Research subject Computer Aided Design
IdentifiersURN: urn:nbn:se:ltu:diva-17690Local ID: 4b05d4ed-23ec-470e-b643-1edefa667abcISBN: 978-91-7583-533-4ISBN: 978-91-7583-534-1OAI: oai:DiVA.org:ltu-17690DiVA: diva2:990695
Godkänd; 2016; 20160127 (erisyn); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Erik Synnegård Ämne: Datorstödd maskinkonstruktion/Computer Aided Design Uppsats: Dynamic Modelling and Analysis of Vertical Machines Examinator: Professor Jan-Olov Aidanpää, Institutionen för teknikvetenskap och matematik, Avdelning: Produkt- och produktionsutveckling, Luleå tekniska universitet. Diskutant: Biträdande Professor Matti Rantatalo, Institutionen för samhällsbyggnad och naturresurser, Avdelning: Drift, underhåll och akustik, Luleå tekniska universitet. Tid: Onsdag 16 mars, 2016 kl 09.00 Plats: E632, Luleå tekniska universitet2016-09-292016-09-29Bibliographically approved