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Statistical and Spectral Analysis of the BulbT Conical Diffuser Flow
Jean-David Buron,Sebastien Houde,Claire Deschenes 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.1
The three dimensional unsteady swirling flow inside the draft tube of a model bulb turbine is investigated using timeresolved stereoscopic particle image velocimetry. The flow is analysed around the best efficiency points for twoN11 values. At N11 = 170, the draft tube flow dynamics are linked to a known efficency drop of the turbine while at N11 = 130, this phenomenon does not occur. This paper presents the experimental setup and provides a complete overview of the measurement campaign based on statistical and spectral analyses of the velocity fields and data from pressure sensors distributed across the draft tube. After the efficiency drop, the intermittency and skewness of the draft tube pressure recovery are found to be reflected onto the velocity fields. For both runner rotation speeds, spectral analyses reveal the presence of a coherent and non-axisymmetric structure that rotates at the same frequency as the runner.
Flow simulation and efficiency hill chart prediction for a Propeller turbine
Vu, Thi,Koller, Marcel,Gauthier, Maxime,Deschenes, Claire Korean Society for Fluid machinery 2011 International journal of fluid machinery and syste Vol.4 No.2
In the present paper, we focus on the flow computation of a low head Propeller turbine at a wide range of design and off-design operating conditions. First, we will present the results on the efficiency hill chart prediction of the Propeller turbine and discuss the consequences of using non-homologous blade geometries for the CFD simulation. The flow characteristics of the entire turbine will be also investigated and compared with experimental data at different measurement planes. Two operating conditions are selected, the first one at the best efficiency point and the second one at part load condition. At the same time, for the same selected operating points, the numerical results for the entire turbine simulation will be compared with flow simulation with our standard stage calculation approach which includes only guide vane, runner and draft tube geometries.