Modern challenges for flow investigations in model hydraulic turbines on classical test rig

Deschênes, Claire; Houde, Sébastien; Aeschlimann, Vincent; Fraser, R; Ciocan, Gabriel Dan

doi:10.1088/1755-1315/22/2/022013

Cited by 8 publications

(1 citation statement)

References 10 publications

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“…The test rig is powered by a pump with a maximal flow rate of 1 m 3 /s and a maximal head of 50 m. The turbine operates with rotational speed up to 2000 rpm and a maximal net power output of 170 kW. A detailed description of the test bench can be found in Deschênes et al (2014). The bulb-shaped turbine model has a reduced scale in the range from 1/10 to 1/15 compared to typical real-world bulb turbines.…”

Section: Experimental Set-up 21 Turbine Set-upmentioning

confidence: 99%

Unsteady flow separation in a turbine diffuser

2015

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Section: Experimental Set-up 21 Turbine Set-upmentioning

confidence: 99%

Unsteady flow separation in a turbine diffuser

2015

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Velocity field investigation inside a bulb turbine runner using endoscopic PIV measurements

et al. 2015

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Modal decomposition of flow instabilities in a straight turbine diffuser around the best efficiency point

Buron

Houde

2023

Physics of Fluids

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Hydraulic turbines sometimes exhibit a sharp efficiency drop around the best efficiency point. The drop is known to originate from large flow separations in their draft tubes, limiting their ability to recover part of the residual kinetic energy exiting the runner. While the conditions leading to the onset of these separations are not yet understood, the potentially unstable vorticity distribution at the runner exit led to the hypothesis that those separations are the result of an interaction between the flow at the center of the draft tube and the boundary layer at the walls. To study this hypothesis, the turbulent flow inside the draft tube of a bulb turbine was measured with time-resolved particle-image velocimetry (TR-PIV). In this work, coherent structures are identified from spectral proper orthogonal decomposition (SPOD) of the velocity fields to correlate changes in their topology with the efficiency drop. Special attention is given to the periodic vortical motions in the runner's wake, whose shape and energy content are found to be linked to the flow rate. Three-dimensional reconstructions of the underlying structure reveal a shift in its topology that correlates with the efficiency drop and separations at the wall. In addition, comparisons of the SPOD coefficients with the runner position show that the phase angle between the structure and the runner remains the same for each operating condition, suggesting a link with a rotating flow imbalance in the runner blade channels.

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Modern challenges for flow investigations in model hydraulic turbines on classical test rig

Cited by 8 publications

References 10 publications

Unsteady flow separation in a turbine diffuser

Unsteady flow separation in a turbine diffuser

Velocity field investigation inside a bulb turbine runner using endoscopic PIV measurements

Modal decomposition of flow instabilities in a straight turbine diffuser around the best efficiency point

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