Study of the internal flow field in a pump-as-turbine (PaT): Numerical investigation, overall performance prediction model and velocity vector analysis

Štefan, David; Rossi, Mosé; Hudec, Martin; Rudolf, Pavel; Nigro, Alessandra

doi:10.1016/j.renene.2020.03.185

Cited by 30 publications

(13 citation statements)

References 42 publications

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“…It is a robust model that allows convergence in a short time, compared to turbulence models such as Reynolds Stress Model (RSM) or Detached Eddy Simulation (DES). On the other hand, a recent study has evidenced errors lower than 4% in CFD studies compared with the experimental curve [55].…”

Section: Step 3: Meshmentioning

confidence: 90%

Characterization of a Commercial Axial Flow PAT Through a Structured Methodology Step-by-Step

Vásquez

Graciano-Uribe

Torres

2022

CFDL

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A centrifugal pump as a turbine (PAT) is the inverse operation of a conventional pump, which takes advantage of the hydraulic energy of water to convert it into rotational mechanical energy and subsequently into electrical energy, through a generator. The CFD analysis allows predicting the fluid dynamic behavior and calculating the operating characteristic curve of the PAT, thus reducing costs in experimental setups. In the literature, the operation of the turbomachine in pump and turbine mode is evidenced. However, there is no methodology applied in commercial axial flow pumps that exposes a structured step-by-step to carry out the numerical and fluid dynamic analysis. In this study, a novel structured methodology is developed describing the numerical and CFD analysis of a commercial axial flow centrifugal pump, which allows validating the characteristic curve in pump mode and then obtaining the site conditions in turbine mode, for its application in small hydroelectric power plants. As a result, in pump mode, an error of less than 8% is obtained between the manufacturer's curve and the numerical curve. In turbine mode, the best performance is around 73%. The aim is to propose a replicable algorithm in future works that allows the proper analysis in commercial axial flow pumps.

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Section: Step 3: Meshmentioning

confidence: 90%

Characterization of a Commercial Axial Flow PAT Through a Structured Methodology Step-by-Step

Vásquez

Graciano-Uribe

Torres

2022

CFDL

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“…The PhD thesis of Singh 28 investigated a mix of 8 radial and one mixed flow turbine, while proposing a prediction and selection model for turbine operation of standard pumps in. 32 Prediction model studies were carried out by Derakhashan et al, 33 Yang et al, 34 Venturini et al 35 to the latest study by Rossi et al 36 and the same validated by Stefan et al 37 The researchers are using different techniques from physics based to statistical based techniques to make accurate prediction models. However, all these models are focused on pumps of radial (centrifugal) shapes which work with heads greater than 15 meters.…”

Section: Context On Alternate and Unconventional Hydro Turbines -Pump As Turbinementioning

confidence: 99%

Classical hydraulic ram pump performance in comparison with modern hydro-turbine pumps for low drive heads

Kesharwani

Tripura

Singh

2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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We present a unique comparison of two types of renewable hydro pumping devices, namely the ram and turbine pump having different working principles. This comparison is based on experiments with these pumping devices at a field station in a village in central-east India. Our work identifies the major gaps in the study of large ram pumps, covering the hydraulic scaling conformance to creation of a unified platform for the investigation of such pumping devices with respect to operating parameters like head, flow, efficiency and, most importantly, size. The field tests of ram revealed that its non-dimensional performance parameters fit perfectly on the theoretical scaling curves. The investigations further showed that while rams had more efficiency (53–62%), they could not handle more than 40–50 l/s of discharge. In comparison, the turbine pumps, tested in laboratory conditions, were more compact for flows beyond 100 l/s, but they settled for overall efficiencies between 49% and 55%. The study recommends a limiting design flow line for rams to be 50 l/s because of the size-factor. It further finds that for absolute flows between 50 and 100 l/s within the low-head range of 3–5 meters, the design of geometrical shapes for turbine pumps could be a challenge for optimized efficiencies. The head-discharge-diameter (H-Q-D) chart developed here is a useful way of interpreting the technology with respect to boundary conditions and it creates a roadmap for future inventions in such renewable hydro-pumping devices. The paper makes a case for axial flow pumps as turbines. It concludes with a call for the propagation of research on such nature-friendly pumping technologies, where most (90–95%) of the water is returned to the stream, paving the way for a new era of sustainability.

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“…In this respect, in addition to PAT performance prediction studies [18][19][20][21][22], investigations into PAT flow unsteadiness under off-design operating conditions and respective flow structure formation mechanism have been carried out, which in the long run should lead to the improvement in terms of PAT's well-balanced performance in both of its operating modes. Among the recently published details on the same topic, a drop in PAT's mechanical efficiency has been recorded under part-load conditions, as a result of flow detachment and swirling flows that occurred within the machine flow channels [23]. In their study, PAT's BEP Flow rate (Q BEP ) and Head (H BEP ) under turbine mode have been found to overtake the pump mode by 27% and 41%, respectively.…”

Section: Introductionmentioning

confidence: 98%

Investigation into Pump Mode Flow Dynamics for a Mixed Flow PAT with Adjustable Runner Blades

et al. 2021

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The adoption of pumps as turbines (PATs) in both small-scale hydroelectric plants and water supply systems has brought about various advantages, the most recognized being cost-effectiveness compared to other hydroturbines. However, due to their lack of flow control ability, their intolerance to off-design operations constitutes a tough shortfall. Moreover, since this technology is new, PAT flow dynamics are not yet well understood. Therefore, this study intends to numerically investigate the mixed-flow PAT’s pump mode flow dynamics for five operating conditions from optimum (1 QBEP) to deep part-load (0.41 QBEP) conditions. Moreover, the effect of runner blade angle on them is investigated, considering three angles, namely −2°, 0°, and 2°. PAT flow stability was found to deteriorate as the flow decreased, where associated pressure pulsation level worsened at different flow zones. In addition, the blade angle increase led to correspondingly increasing flow unsteadiness and pressure pulsation levels, where the pulsation frequencies from rotor-stator interactions were dominant for most flow zones. This study’s findings are of crucial importance to both scientific and engineering communities as they contribute to a thorough understanding of PAT flow dynamics.

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Study of the internal flow field in a pump-as-turbine (PaT): Numerical investigation, overall performance prediction model and velocity vector analysis

Cited by 30 publications

References 42 publications

Characterization of a Commercial Axial Flow PAT Through a Structured Methodology Step-by-Step

Characterization of a Commercial Axial Flow PAT Through a Structured Methodology Step-by-Step

Classical hydraulic ram pump performance in comparison with modern hydro-turbine pumps for low drive heads

Investigation into Pump Mode Flow Dynamics for a Mixed Flow PAT with Adjustable Runner Blades

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