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Load variation effects on the pressure fluctuations exerted on a Kaplan turbine runner
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
Vattenfall Research & Development.
School of Mechanical Engineering, University of Tehran, Mechanical Engineering Department, University of Tehran.
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
2014 (English)In: 27th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2014: Montreal, Canada, 22- 26 September 2014 / [ed] A-M Giroux, IOP Publishing Ltd , 2014, 32005Conference paper (Refereed)
Abstract [en]

Introduction of intermittent electricity production systems like wind power and solar systems to electricity market together with the consumption-based electricity production resulted in numerous start/stops, load variations and off-design operation of water turbines. The hydropower systems suffer from the varying loads exerted on the stationary and rotating parts of the turbines during load variations which they are not designed for. On the other hand, investigations on part load operation of single regulated turbines, i.e., Francis and propeller, proved the formation of rotating vortex rope (RVR) in the draft tube. The RVR induces oscillating flow both in plunging and rotating modes which results in oscillating force with two different frequencies on the runner blades, bearings and other rotating parts of the turbine. The purpose of this study is to investigate the effect of transient operations on the pressure fluctuations on the runner and mechanism of the RVR formation/mitigation. Draft tube and runner blades of the Porjus U9 model, a Kaplan turbine, were equipped with pressure sensors. The model was run in off-cam mode during different load variation conditions to check the runner performance under unsteady condition. The results showed that the transients between the best efficiency point and the high load happens in a smooth way while transitions to/from the part load, where rotating vortex rope (RVR) forms in the draft tube induces high level of fluctuations with two frequencies on the runner; plunging and rotating mode of the RVR.

Place, publisher, year, edition, pages
IOP Publishing Ltd , 2014. 32005
I O P Conference Series: Earth and Environmental Science, ISSN 1755-1307 ; 22
Research subject
Fluid Mechanics
URN: urn:nbn:se:ltu:diva-40572DOI: 10.1088/1755-1315/22/3/032005ScopusID: 84919632882Local ID: fc08b6b8-5395-4286-9136-f2022232b363OAI: diva2:1014094
IAHR Symposium on Hydraulic Machinery and Systems : 22/09/2014 - 26/09/2014
Validerad; 2015; Nivå 1; 20150107 (andbra)Available from: 2016-10-03 Created: 2016-10-03Bibliographically approved

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