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dc.contributor.authorOlimstad, Grundenb_NO
dc.date.accessioned2014-12-19T11:49:58Z
dc.date.available2014-12-19T11:49:58Z
dc.date.created2012-12-21nb_NO
dc.date.issued2012nb_NO
dc.identifier581794nb_NO
dc.identifier.isbn978-82-471-3919-6, h.nb_NO
dc.identifier.isbn978-82-471-3920-2nb_NO
dc.identifier.urihttp://hdl.handle.net/11250/234993
dc.description.abstractThe primary goal for this PhD project has been to investigate instability of reversiblepump turbines (RPTs) as a phenomenon and to find remedies to solve it. The instability occurs for turbines with s-shaped characteristics, unfavourable waterways and limited rotating inertia. It is only observed for certain operation points at either high speed or low load. These correspond to either high values of Ned or low values of Qed. The work done in this PhD thesis can be divided into the three following categories. Investigate and understand the behaviour of a pump turbine: A model was designed in order to investigate the pump turbine behaviour related to its characteristics. This model was manufactured and measurements were performed in the laboratory. By using throttling valves or torque as input the full s-shaped characteristics was measured. When neither of these techniques is used, the laboratory system has unstable operation points which result in hysteresis behaviour. Global behaviour of the RPT in a power plant system was investigated through analytical stability analysis and dynamic system simulations. The latter included both rigid and elastic representation of the water column. Turbine internal flow: The flow inside the runner was investigated by computer simulations (CFD). Two-dimensional analysis was used to study the inlet part of the runner. This showed that a vortex forming at the inlet is one of the causes for the unstable characteristics. Three-dimensional analyses were performed and showed multiple complex flow structures in the unstable operation range. Measurements at different pressure levels showed that the characteristics were dependent on the Reynolds number at high Ned values in turbine mode. This means that the similarity of flows is not sufficiently described by constant Qed and Ned values at this part of the characteristics. Design modifications: The root of the stability problem was considered to be the runner’s geometric design at the inlet in turbine mode. Therefore different design parameters were investigated to find relations to the characteristics. Methods used were measurements, CFD modelling and analytical models. The leading edge profile was altered on the physical model and measurements were performed in the laboratory. Results showed that the profiles have significant influence on characteristics and therewith stability at high speed operation points. Other design parameters were investigated by CFD analysis with special focus on the inlet blade angle.nb_NO
dc.languageengnb_NO
dc.publisherNorges teknisk-naturvitenskapelige universitet, Fakultet for ingeniørvitenskap og teknologi, Institutt for energi- og prosessteknikknb_NO
dc.relation.ispartofseriesDoktoravhandlinger ved NTNU, 1503-8181; 2012:301nb_NO
dc.relation.haspartOlimstad, Grunde; Nielsen, Torbjørn Kristian; Børresen, Bjarne. Dependancy on Runner Geometry for Reversible-Pump Turbine Characteristics in Turbine Mode of Operation. Journal of Fluids Engineering - Trancactions of The ASME. (ISSN 0098-2202). 134(12), 2012. <a href='http://dx.doi.org/10.1115/1.4007897'>10.1115/1.4007897</a>.nb_NO
dc.relation.haspartOlimstad, Grunde; Nielsen, Torbjørn Kristian; Børresen, Bjarne. Stability Limits of Reversible-Pump Turbines in Turbine Mode of Operation and Measurements of Unstable Characteristics. Journal of Fluids Engineering - Trancactions of The ASME. (ISSN 0098-2202). 134(11), 2012. <a href='http://dx.doi.org/10.1115/1.4007589'>10.1115/1.4007589</a>.nb_NO
dc.relation.haspartOlimstad, Grunde. Design of a Reversible Pump-Turbine -with Purpose to Investigate Stability. Proceedings of the 4 th International Meeting on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems, 2011.nb_NO
dc.relation.haspartOlimstad, Grunde; Nielsen, Torbjørn Kristian; Børresen, Bjarne. A Two-Dimensional Model for Pump-Turbine Instability Investigations. 14 th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC-14, 2012.nb_NO
dc.relation.haspartOlimstad, Grunde; Nielsen, Torbjørn Kristian; Børresen, Bjarne. Geomatry Impact on Pump-Turbine Characteristics. 14 th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, 2012.nb_NO
dc.relation.haspartNielsen, Torbjørn Kristian; Olimstad, Grunde. Dynamic Behaviour of Reversible Pump-Turbines in Turbine Mode of Operation. International Symposium on Transport Phenomena and Dynamics of Rotating Machine: Paper ID-No:60, 2010.nb_NO
dc.subjectPump Turbinesen_GB
dc.subjectStabilityen_GB
dc.subjectDesignen_GB
dc.subjectCFDen_GB
dc.subjectMeasurementsen_GB
dc.titleCharacteristics of reversible-pump turbinesnb_NO
dc.typeDoctoral thesisnb_NO
dc.contributor.departmentNorges teknisk-naturvitenskapelige universitet, Fakultet for ingeniørvitenskap og teknologi, Institutt for energi- og prosessteknikknb_NO
dc.description.degreePhD i energi- og prosessteknikknb_NO
dc.description.degreePhD in Energy and Process Engineeringen_GB


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