Modelling and optimization of the velocity profiles at the draft tube inlet of a Francis turbine within an operating range

Ciocan, Tiberiu; Susan-Resiga, Romeo; Muntean, Sebastian

doi:10.1080/00221686.2015.1119763

Cited by 19 publications

(9 citation statements)

References 27 publications

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“…The pair (m = 0, n = 0.278) is obtained based on numerical simulations for Francis runner available in the hydropower plant as shown in Figure 5b. The same values are yielded based on the experimental data of the GAMM Francis model [20]. A constant swirl-free velocity profile corresponds to the classical design of the runner blades.…”

Section: The Old and New Solutions For A Francis Runnermentioning

confidence: 94%

“…Locally, where the meridian velocity matches the swirl-free velocity the circumferential velocity vanishes. The swirl-free velocity profile practically remains unchanged at all operating points [16,20] being unique for each runner. One can approximate the swirl-free velocity with a linear equation v sf = n + mq where q is the discharge fraction.…”

Section: The Old and New Solutions For A Francis Runnermentioning

confidence: 98%

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Scenarios for refurbishment of a hydropower plant equipped with Francis turbines

Muntean

Susan-Resiga

Göde

et al. 2016

Renew. Energy Environ. Sustain.

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The energy market imposes new requirements in hydraulic turbines operation. Usually, the old hydraulic turbines are not designed to meet these new requirements. Therefore, the refurbished solutions for hydraulic turbines are expected to be robust and flexible in operation in order to regulate the grid. A methodology is developed for a hydropower plant equipped with Francis turbines. Firstly, the solution available in the hydropower plant is examined. Secondly, two new solutions are designed for the hydraulic passage available in situ. Next, several scenarios from peak load operation to wide range operation are investigated in order to asses the performance of each technical solution. Consequently, the performances are compared proving the best solution for hydropower plant refurbishment.

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Section: The Old and New Solutions For A Francis Runnermentioning

confidence: 94%

Section: The Old and New Solutions For A Francis Runnermentioning

confidence: 98%

Scenarios for refurbishment of a hydropower plant equipped with Francis turbines

Muntean

Susan-Resiga

Göde

et al. 2016

Renew. Energy Environ. Sustain.

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“…Lyutov [9] described a coupled optimization of runner and draft tubes, where their geometries were varied simultaneously, allowing to achieve a 0.3% higher efficiency gain compared to single-runner optimization. Ciocan [10] presented a draft tube optimization from part to full load, using a parameterized velocity field at the tube entry based on a swirl-free velocity profile for the runner. Eisinger [11] reported an automatic draft tube optimization, but no coupling of the inflow conditions with the attached runner was present.…”

Section: Introductionmentioning

confidence: 99%

Two-Objective Optimization of a Kaplan Turbine Draft Tube Using a Response Surface Methodology

Orso

Benini

Minozzo³

et al. 2020

Energies

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The overall cost of a hydropower plant is mainly due to the expenses of civil works, mechanical equipment (turbine and control units) and electrical components. The goal of a new draft tube design is to obtain a geometry that reduces investment costs, especially the excavation ones, but the primary driver is to increase overall machine efficiency, allowing for a reduced payback time. In the present study, an optimization study of the elbow-draft tube assembly of a Kaplan turbine was conducted. First, a CFD model for the complete turbine was developed and validated. Next, an optimization of the draft tube alone was performed using a design of experiments technique. Finally, several optimum solutions for the draft tube were obtained using a response surface technique aiming at maximizing pressure recovery and minimizing flow losses. A selection of optimized geometries was subsequently post-checked using the validated model of the entire turbine, and a detailed flow analysis on the obtained results made it possible to provide insights into the improved designs. It was observed that efficiency could be improved by 1% (in relative terms), and the mechanical power increased by 1.8% (in relative terms) with respect to the baseline turbine.

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“…The flow energy which is not converted by the runner is ingested by the drat tube of the hydraulic turbines [8]. A fraction of this residual energy is converted back into potential energy along to the draft tube [9].…”

Section: Introductionmentioning

confidence: 99%

A Novel Passive Method to Control the Swirling Flow with Vortex Rope from the Conical Diffuser of Hydraulic Turbines with Fixed Blades

et al. 2019

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In this paper, we introduce a novel passive control method to mitigate the unsteadiness effects associated to the swirling flows with self-induced instabilities. The control method involves a progressive throttling cross-section flow at the outlet of the conical diffuser. It adjusts the cross-section area with a diaphragm while maintaining all positions of the circular shape centered on the axis. It improves the pressure recovery on the cone wall while the pressure fluctuations associated with the self-induced instability are mitigated as it adjusts the cross-section area. It can adjust the diaphragm in correlation with the operating conditions of the turbine. We investigated the passive control method on a swirl generator, which provides a similar flow as a hydraulic turbine operated at a partial discharge. The plunging and rotating components are discriminated using the pressure fluctuation on the cone wall to provide a clear view of the effects induced by this passive control method. As a result, the novel proof of concept examined in this paper offers valuable benefits as it fulfils a good balance between the dynamical behavior and the hydraulic losses.

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Modelling and optimization of the velocity profiles at the draft tube inlet of a Francis turbine within an operating range

Cited by 19 publications

References 27 publications

Scenarios for refurbishment of a hydropower plant equipped with Francis turbines

Scenarios for refurbishment of a hydropower plant equipped with Francis turbines

Two-Objective Optimization of a Kaplan Turbine Draft Tube Using a Response Surface Methodology

A Novel Passive Method to Control the Swirling Flow with Vortex Rope from the Conical Diffuser of Hydraulic Turbines with Fixed Blades

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