LDA measurements in the Francis-99 draft tube cone

Velocity measurements were performed in the draft tube cone of a 1:5.1 scaled model of the Tokke hydropower plant, Norway; also known as the Francis-99 model. Results from the laser Doppler anemometry measurements undertaken at three operating points will be used as validation data for an upcoming w...

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Bibliographic Details
Published in:IOP conference series. Earth and environmental science 2014-01, Vol.22 (2), p.22012-22021
Main Authors: Sundstrom, L R J, Amiri, K, Bergan, C, Cervantes, M J, Dahlhaug, O G
Format: Article
Language:English
Subjects:
Angular speed
Computational fluid dynamics
Draft tubes
Efficiency
Flow rates
Flow velocity
Fluid flow
Hydraulic loading
Hydroelectric plants
Hydroelectric power
Mathematical models
Parameter sensitivity
Peak load
Rope
Rotating
Rotation
Sensitivity analysis
Turbines
Velocity
Velocity distribution
Velocity measurement
Vortex breakdown
Vortices
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Summary:Velocity measurements were performed in the draft tube cone of a 1:5.1 scaled model of the Tokke hydropower plant, Norway; also known as the Francis-99 model. Results from the laser Doppler anemometry measurements undertaken at three operating points will be used as validation data for an upcoming workshop on the state of the art of Francis turbine numerical simulation. With the turbine operating at the best efficiency point, a sensitivity analysis of the flow parameters head, flow rate and runner rotational speed shows that the effects on the dimensionless velocity profiles are small as long as n sub(ED) and Q sub(ED) are held constant. The results indicate a well-functioning turbine at the best efficiency point and high load. At the part load operating point, a vortex breakdown occurs which distorts the velocity profiles and significantly lowers the turbine's hydraulic efficiency. Frequency spectrums of each LDA signal at part load reveals a peak which is asynchronous to that of the runner angular speed. The peaks might be related to the precession of a rotating vortex rope but the characteristics of the LDA signals are different compared to previous studies involving rotating vortex ropes.
ISSN:1755-1307
1755-1315
DOI:10.1088/1755-1315/22/2/022012