2025
Shen, Jiantao; Jia, Xuanwen; Cheng, Li; Jiao, Weixuan; Zhang, Bowen; Pavesi, Giorgio
Investigation into the coupling mechanism of tailwater vortex dynamics and cavitation during pump-as-turbine operations Journal Article
In: Physics of Fluids, vol. 37, iss. 10, 2025, ISSN: 10897666.
Abstract | Links | BibTeX | Tags: Cavitation, PAT, Pump as Turbine
@article{Shen2025b,
title = {Investigation into the coupling mechanism of tailwater vortex dynamics and cavitation during pump-as-turbine operations},
author = {Jiantao Shen and Xuanwen Jia and Li Cheng and Weixuan Jiao and Bowen Zhang and Giorgio Pavesi},
doi = {10.1063/5.0287323},
issn = {10897666},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
journal = {Physics of Fluids},
volume = {37},
issue = {10},
publisher = {American Institute of Physics},
abstract = {In order to investigate the coupling mechanism between tailwater vortex and cavitation bubbles (CB) during the operation of a low-head pump-as-turbine (PAT), the method of combining experiment and numerical simulation is used to quantify the vortex dynamics characteristics in combination with the vorticity transport equation under high flow conditions for PAT mode. The results show that the decrease in Thoma number significantly regulates the symbiotic evolution of tailwater vortex and CB: prolonging the residence time of CB in the draft tube (DT) and changing its evolution mode, resulting in the extension of vortex rope (VR) generation period, length contraction, and the increase in breaking vortex in DT. The peak volume of CB is 7 times that in the rotor region, squeezing the channel vortex and the wake vortex, weakening its contribution to VR. Vortex dynamics shows that the relative vortex stretching term is the core driving force of vorticity, which causes velocity gradient distortion and VR high-frequency oscillation synchronously with vertical vorticity. The baroclinic torque term (BT) only generates pulse contribution in the early stage of CB collapse. Under critical cavitation, BT converts the cavity collapse energy into vortex energy through density-pressure gradient coupling, which expands the vortex core radius to 0.03 m, increases the circulation peak to 2.3 m2/s, and shifts outward by 27.3%, resulting in vortex energy diffusion and high-frequency oscillation of the flow field. This study provides a theoretical basis for cavitation suppression and operational optimization of low-head PAT.},
key = {Cavitation, PAT, Pump as Turbine, tailwater vortex},
keywords = {Cavitation, PAT, Pump as Turbine},
pubstate = {published},
tppubtype = {article}
}
In order to investigate the coupling mechanism between tailwater vortex and cavitation bubbles (CB) during the operation of a low-head pump-as-turbine (PAT), the method of combining experiment and numerical simulation is used to quantify the vortex dynamics characteristics in combination with the vorticity transport equation under high flow conditions for PAT mode. The results show that the decrease in Thoma number significantly regulates the symbiotic evolution of tailwater vortex and CB: prolonging the residence time of CB in the draft tube (DT) and changing its evolution mode, resulting in the extension of vortex rope (VR) generation period, length contraction, and the increase in breaking vortex in DT. The peak volume of CB is 7 times that in the rotor region, squeezing the channel vortex and the wake vortex, weakening its contribution to VR. Vortex dynamics shows that the relative vortex stretching term is the core driving force of vorticity, which causes velocity gradient distortion and VR high-frequency oscillation synchronously with vertical vorticity. The baroclinic torque term (BT) only generates pulse contribution in the early stage of CB collapse. Under critical cavitation, BT converts the cavity collapse energy into vortex energy through density-pressure gradient coupling, which expands the vortex core radius to 0.03 m, increases the circulation peak to 2.3 m2/s, and shifts outward by 27.3%, resulting in vortex energy diffusion and high-frequency oscillation of the flow field. This study provides a theoretical basis for cavitation suppression and operational optimization of low-head PAT.
2024
Zhang, Chenying; Wang, Wenjie; Pavesi, Giorgio; Yuan, Shouqi; Pei, Ji
Research on the mechanism of severe unsteadiness of PAT braking condition during the power failure Journal Article
In: Renewable Energy, vol. 232, 2024, ISSN: 18790682.
Abstract | Links | BibTeX | Tags: Braking conditions, CFD numerical simulation, Energy loss, Pump as Turbine, Transient characteristics, Unsteady Flow Evolution
@article{Zhang2024,
title = {Research on the mechanism of severe unsteadiness of PAT braking condition during the power failure},
author = {Chenying Zhang and Wenjie Wang and Giorgio Pavesi and Shouqi Yuan and Ji Pei},
doi = {10.1016/j.renene.2024.121019},
issn = {18790682},
year = {2024},
date = {2024-01-01},
journal = {Renewable Energy},
volume = {232},
publisher = {Elsevier Ltd},
abstract = {The Pump-As-Turbine (PAT) technology has become popular in micro hydropower stations due to its simple installation and cost-effectiveness. Nevertheless, power failures present a substantial risk to the secure and steady functioning of PAT's braking system. The commercial CFD code (ANSYSCFX) is improved by incorporating a secondary development to model the power-off transition using Fortran accurately. This enhancement allows for real-time iterative calculations of angular momentum equations for mixed-flow PAT at different speeds. Meanwhile, the time–frequency domain analysis is utilized to analyze pressure pulsation signals and the evolution of the internal flow field in mixed-flow PAT. An investigation was conducted to have a deeper understanding of braking circumstances. The results revealed that the main frequency of the pressure pulsation aligns with the blade frequency at various flow rates, and there is a sudden change in pressure amplitude during the braking phase. The impeller experienced the majority of energy losses, with the draft tube being the subsequent area of concern. In addition, a thorough examination and comparison of the changes in the internal flow field during braking were carried out. This analysis revealed a distinct double helix structure within the draft tube, with a slower inner helix and a faster outer helix. Furthermore, it was observed that there is a strong correlation between wall shear stresses and hydraulic losses on the blade surface. This research enhanced understanding of the flow characteristics of mixed-flow PAT can help improve system safety and provide valuable guidance for future optimization efforts.},
keywords = {Braking conditions, CFD numerical simulation, Energy loss, Pump as Turbine, Transient characteristics, Unsteady Flow Evolution},
pubstate = {published},
tppubtype = {article}
}
The Pump-As-Turbine (PAT) technology has become popular in micro hydropower stations due to its simple installation and cost-effectiveness. Nevertheless, power failures present a substantial risk to the secure and steady functioning of PAT's braking system. The commercial CFD code (ANSYSCFX) is improved by incorporating a secondary development to model the power-off transition using Fortran accurately. This enhancement allows for real-time iterative calculations of angular momentum equations for mixed-flow PAT at different speeds. Meanwhile, the time–frequency domain analysis is utilized to analyze pressure pulsation signals and the evolution of the internal flow field in mixed-flow PAT. An investigation was conducted to have a deeper understanding of braking circumstances. The results revealed that the main frequency of the pressure pulsation aligns with the blade frequency at various flow rates, and there is a sudden change in pressure amplitude during the braking phase. The impeller experienced the majority of energy losses, with the draft tube being the subsequent area of concern. In addition, a thorough examination and comparison of the changes in the internal flow field during braking were carried out. This analysis revealed a distinct double helix structure within the draft tube, with a slower inner helix and a faster outer helix. Furthermore, it was observed that there is a strong correlation between wall shear stresses and hydraulic losses on the blade surface. This research enhanced understanding of the flow characteristics of mixed-flow PAT can help improve system safety and provide valuable guidance for future optimization efforts.
Zhang, Chenying; Pavesi, Giorgio; Pei, Ji; Wang, Wenjie; Yuan, Shouqi; Shen, Jiawei
Unstable flow analysis of transient process in the pump as turbine during turbine mode caused by pump power failure Journal Article
In: Physics of Fluids, vol. 36, iss. 11, 2024, ISSN: 10897666.
Abstract | Links | BibTeX | Tags: PAT, Power Failure, Pump as Turbine, Runaway
@article{Zhang2024c,
title = {Unstable flow analysis of transient process in the pump as turbine during turbine mode caused by pump power failure},
author = {Chenying Zhang and Giorgio Pavesi and Ji Pei and Wenjie Wang and Shouqi Yuan and Jiawei Shen},
doi = {10.1063/5.0233491},
issn = {10897666},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Physics of Fluids},
volume = {36},
issue = {11},
publisher = {American Institute of Physics},
abstract = {Mixed-flow pump as turbines (PATs) serve as pivotal components within energy micro-grids, facilitating energy conversion and storage. However, the emergence of pressure pulsations in these systems can markedly affect their stability and efficiency, especially in pump power failure. To simulate the power-off transition accurately, the commercial computational fluid dynamics code ANSYS CFX® is integrated by a Fortran program through ANSYS parametric design language in the transient simulation to enable real-time iterative calculations of angular momentum equations for mixed-flow PAT at varying speeds. This study integrates the analysis of radial forces, vortices, and flow lines to elucidate the sudden changes in pressure pulsations observed during the transition stages. Specifically, significant fluctuations in the amplitude of pressure pulsations at the volute tongue were found for various initial flow rates, which correlated closely with changes in radial forces. The sudden increase and nonuniform distribution of radial forces emerged as the main factors of these fluctuations. In addition, the study reveals that the intensity of pressure fluctuations evidenced by wavelet time-frequency analysis on the pressure surface of the blade significantly exceeds that on the back surface of the blade. Furthermore, in the flow characteristics inside the draft tube, the pressure pulsation signals are mainly concentrated in the low-frequency region and are accompanied by the presence of a double-helix structure. These results provide an important reference for further understanding of the operating mechanism of the mixed-flow pump as a turbine, which helps to optimize the design and improve the performance.},
keywords = {PAT, Power Failure, Pump as Turbine, Runaway},
pubstate = {published},
tppubtype = {article}
}
Mixed-flow pump as turbines (PATs) serve as pivotal components within energy micro-grids, facilitating energy conversion and storage. However, the emergence of pressure pulsations in these systems can markedly affect their stability and efficiency, especially in pump power failure. To simulate the power-off transition accurately, the commercial computational fluid dynamics code ANSYS CFX® is integrated by a Fortran program through ANSYS parametric design language in the transient simulation to enable real-time iterative calculations of angular momentum equations for mixed-flow PAT at varying speeds. This study integrates the analysis of radial forces, vortices, and flow lines to elucidate the sudden changes in pressure pulsations observed during the transition stages. Specifically, significant fluctuations in the amplitude of pressure pulsations at the volute tongue were found for various initial flow rates, which correlated closely with changes in radial forces. The sudden increase and nonuniform distribution of radial forces emerged as the main factors of these fluctuations. In addition, the study reveals that the intensity of pressure fluctuations evidenced by wavelet time-frequency analysis on the pressure surface of the blade significantly exceeds that on the back surface of the blade. Furthermore, in the flow characteristics inside the draft tube, the pressure pulsation signals are mainly concentrated in the low-frequency region and are accompanied by the presence of a double-helix structure. These results provide an important reference for further understanding of the operating mechanism of the mixed-flow pump as a turbine, which helps to optimize the design and improve the performance.
2015
Pavesi, Giorgio; Yang, Jun; Cavazzini, Giovanna; Ardizzon, Guido
Experimental analysis of instability phenomena in a high-head reversible pump-turbine at large partial flow condition Proceedings Article
In: 11th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2015, pp. 1-2, euroturbo.eu, 2015, ISSN: 24104833.
Abstract | Links | BibTeX | Tags: Flow instability, Francis Turbine, Francis-type Reversible Turbine, Hump instability, PAT, Pump as Turbine
@inproceedings{pop00010,
title = {Experimental analysis of instability phenomena in a high-head reversible pump-turbine at large partial flow condition},
author = {Giorgio Pavesi and Jun Yang and Giovanna Cavazzini and Guido Ardizzon},
url = {http://www.euroturbo.eu/paper/ETC2015-060.pdf},
issn = {24104833},
year = {2015},
date = {2015-01-01},
urldate = {2015-01-01},
booktitle = {11th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2015},
pages = {1-2},
publisher = {euroturbo.eu},
abstract = {Growing environmental concerns, and the need for better power balancing and frequency control have increased attention in renewable energy sources, such as, the reversible pump-turbine which can provide both power generation and energy storage. Pump-turbine operation along the hump-shaped curve can lead to unusual increases in water pressure pulsations, which lead to machine vibrations. Measurements of wall pressure in the stators were performed together with high-speed flow visualizations. Starting from the best efficiency point (BEP) and by decreasing the flowrate, a significant increase of the pressure fluctuations was observed mainly in the wicket gates channels. The analyses in frequency and time-frequency domains showed a rise of low frequency components. High-speed movies revealed a quite uniform flow pattern in the guide vanes channels at the normal operating range, whereas, the flow was highly disturbed by rotating stall passage at part load. The situation was more critical in the dump flow rate range, where backflow and vortices in the guide vanes channels developed during the stall cell passage.},
keywords = {Flow instability, Francis Turbine, Francis-type Reversible Turbine, Hump instability, PAT, Pump as Turbine},
pubstate = {published},
tppubtype = {inproceedings}
}
Growing environmental concerns, and the need for better power balancing and frequency control have increased attention in renewable energy sources, such as, the reversible pump-turbine which can provide both power generation and energy storage. Pump-turbine operation along the hump-shaped curve can lead to unusual increases in water pressure pulsations, which lead to machine vibrations. Measurements of wall pressure in the stators were performed together with high-speed flow visualizations. Starting from the best efficiency point (BEP) and by decreasing the flowrate, a significant increase of the pressure fluctuations was observed mainly in the wicket gates channels. The analyses in frequency and time-frequency domains showed a rise of low frequency components. High-speed movies revealed a quite uniform flow pattern in the guide vanes channels at the normal operating range, whereas, the flow was highly disturbed by rotating stall passage at part load. The situation was more critical in the dump flow rate range, where backflow and vortices in the guide vanes channels developed during the stall cell passage.
2014
Stoppato, Anna; Cavazzini, Giovanna; Ardizzon, Guido; Rossetti, Antonio
In: Energy, vol. 76, pp. 168-174, 2014, ISSN: 03605442.
Abstract | Links | BibTeX | Tags: Energy storage, Particle swarm theory, Photovoltaic pumping systems, Pump as Turbine, Water cooling, Water saving
@article{Stoppato2014a,
title = {A PSO (particle swarm optimization)-based model for the optimal management of a small PV(Photovoltaic)-pump hydro energy storage in a rural dry area},
author = {Anna Stoppato and Giovanna Cavazzini and Guido Ardizzon and Antonio Rossetti},
url = {http://linkinghub.elsevier.com/retrieve/pii/S0360544214006999},
doi = {10.1016/j.energy.2014.06.004},
issn = {03605442},
year = {2014},
date = {2014-01-01},
journal = {Energy},
volume = {76},
pages = {168-174},
abstract = {In developing countries, the exploitation of renewable sources is an opportunity to increase the number of people who have simple access to electricity and to water. Among other technologies, stand-alone photovoltaic pumping systems are often installed in remote areas where the grid is not available: they are used for irrigation and/or other local water needs and can supply also electricity to small consumers. In this paper, by means of an optimization model based on the Particle Swarm Theory, the managing strategy of a system aimed at supplying electricity and water to an isolated small village in Nigeria has been optimized in order to fulfill the requirement of the users and to improve the system efficiency. Ground water is pumped into a storage reservoir and can be used both for irrigation and domestic use. The system is composed by a photovoltaic plant, a pump as turbine, a pack of batteries and a diesel internal combustion engine for integration purposes. A simultaneous optimization of both devices size and plant management has been performed in order to achieve the best economic performances or to fulfil the requirement only by renewable sources. In the first case, the use of a pump as turbine permits to save about 4% of diesel oil, even if the low cost of fuel makes it convenient to use the engine. In the latter case the optimum size of photovoltaic plant is about 16 times higher than in the first one, while the batteries' and pump's optimum sizes are strictly connected to the maximum allowable value for the water storage volume. © 2014 Elsevier Ltd. All rights reserved.},
keywords = {Energy storage, Particle swarm theory, Photovoltaic pumping systems, Pump as Turbine, Water cooling, Water saving},
pubstate = {published},
tppubtype = {article}
}
In developing countries, the exploitation of renewable sources is an opportunity to increase the number of people who have simple access to electricity and to water. Among other technologies, stand-alone photovoltaic pumping systems are often installed in remote areas where the grid is not available: they are used for irrigation and/or other local water needs and can supply also electricity to small consumers. In this paper, by means of an optimization model based on the Particle Swarm Theory, the managing strategy of a system aimed at supplying electricity and water to an isolated small village in Nigeria has been optimized in order to fulfill the requirement of the users and to improve the system efficiency. Ground water is pumped into a storage reservoir and can be used both for irrigation and domestic use. The system is composed by a photovoltaic plant, a pump as turbine, a pack of batteries and a diesel internal combustion engine for integration purposes. A simultaneous optimization of both devices size and plant management has been performed in order to achieve the best economic performances or to fulfil the requirement only by renewable sources. In the first case, the use of a pump as turbine permits to save about 4% of diesel oil, even if the low cost of fuel makes it convenient to use the engine. In the latter case the optimum size of photovoltaic plant is about 16 times higher than in the first one, while the batteries' and pump's optimum sizes are strictly connected to the maximum allowable value for the water storage volume. © 2014 Elsevier Ltd. All rights reserved.
2012
Cavazzini, Giovanna; Dazin, Antoine; Pavesi, Giorgio; Dupont, P.; Bois, Gerard
Post-processing methods of PIV instantaneous flow fields for unsteady flows in turbomachines Book
hal.archives-ouvertes.fr, 2012.
Abstract | Links | BibTeX | Tags: PIV, Pump as Turbine
@book{pop00022,
title = {Post-processing methods of PIV instantaneous flow fields for unsteady flows in turbomachines},
author = {Giovanna Cavazzini and Antoine Dazin and Giorgio Pavesi and P. Dupont and Gerard Bois},
url = {https://hal.archives-ouvertes.fr/hal-00794858/},
doi = {10.5772/37273},
year = {2012},
date = {2012-01-01},
urldate = {2012-01-01},
journal = {The Particle Image Velocimetry - Characteristics, Limits and Possible Applications},
publisher = {hal.archives-ouvertes.fr},
abstract = {Among the experimental techniques, the particle image velocimetry (PIV) is undoubtedly one of the most attractive modern methods to investigate the fluid flow in a non-intrusive way and allows to obtain instantaneous fluid flow fields by correlating at least two sequential exposures. This technique was successfully applied in several fields in order to study high complex three-dimensional flow velocity fields and to provide a significant experimental data base for the validation of combined numerical analysis models. However, on one side, experimental limits and possible perturbing phenomena could negatively affect the PIV experimental accuracy, altering the real physics of the studied fluid flow field. On the other side, the huge amount of data obtainable by means of the PIV technique requires properly post-processing tools to be exploited in an in-depth study of the fluid-dynamical phenomena. To avoid misinterpretation of the phenomena, complex cleaning techniques were developed and applied at the different steps of the PIV processing, starting from the acquired images (background subtraction, mask application, etc.) so as to increase the signal to noise ratio, and finishing to the instantaneous flow fields by means of statistical methods applied in order to identify residual spurious vectors [Raffel et al., 2002]. Even though all these methods allows to obtain a good filtering of the instantaneous flow fields, however they are not able to completely eliminate all the outliers in the results since the removal criteria are always dependent on the choice of a threshold value [Heinz et al., 2004; Westerweeel, 1994; Westerweel and Scarano, 2005]. To overcome this problem, the most common approach is to average the instantaneous PIV flow fields so as to improve the quality of the resulting flow field reconstruction and to more easily identify the flow field characteristics in the investigated area.},
keywords = {PIV, Pump as Turbine},
pubstate = {published},
tppubtype = {book}
}
Among the experimental techniques, the particle image velocimetry (PIV) is undoubtedly one of the most attractive modern methods to investigate the fluid flow in a non-intrusive way and allows to obtain instantaneous fluid flow fields by correlating at least two sequential exposures. This technique was successfully applied in several fields in order to study high complex three-dimensional flow velocity fields and to provide a significant experimental data base for the validation of combined numerical analysis models. However, on one side, experimental limits and possible perturbing phenomena could negatively affect the PIV experimental accuracy, altering the real physics of the studied fluid flow field. On the other side, the huge amount of data obtainable by means of the PIV technique requires properly post-processing tools to be exploited in an in-depth study of the fluid-dynamical phenomena. To avoid misinterpretation of the phenomena, complex cleaning techniques were developed and applied at the different steps of the PIV processing, starting from the acquired images (background subtraction, mask application, etc.) so as to increase the signal to noise ratio, and finishing to the instantaneous flow fields by means of statistical methods applied in order to identify residual spurious vectors [Raffel et al., 2002]. Even though all these methods allows to obtain a good filtering of the instantaneous flow fields, however they are not able to completely eliminate all the outliers in the results since the removal criteria are always dependent on the choice of a threshold value [Heinz et al., 2004; Westerweeel, 1994; Westerweel and Scarano, 2005]. To overcome this problem, the most common approach is to average the instantaneous PIV flow fields so as to improve the quality of the resulting flow field reconstruction and to more easily identify the flow field characteristics in the investigated area.
2007
Pavesi, Giorgio; Cavazzini, Giovanna; Dupont, Patrick; Coudert, Sebastien; Caignaert, Guy; Bois, Gérard; Ardizzon, Guido
Rotor-stator interactions in a radial flow pump Proceedings Article
In: Proceedings of the 7th European Conference on Turbomachinery: Fluid Dynamics and Thermodynamics, ETC 2007, 2007, (<b>From Duplicate 1 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, G; Cavazzini, G; Dupont, P; Coudert, S.; Caignaert, G.; Bois, G.; Ardizzon, G.)<br/></b><br/>Query date: 2017-05-06<br/><br/><b>From Duplicate 2 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, Giorgio; Cavazzini, Giovanna; Dupont, Patrick; Coudert, Sebastien; Caignaert, Guy; Bois, Gérard; Ardizzon, Guido)<br/></b><br/><b>From Duplicate 2 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, G; Cavazzini, G; Dupont, P; Coudert, S.; Caignaert, G.; Bois, G.; Ardizzon, G.)<br/>And Duplicate 3 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, G; Cavazzini, G; Dupont, P; Coudert, S.; Caignaert, G.; Bois, G.; Ardizzon, G.)<br/>And Duplicate 4 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, G; Cavazzini, G; Dupont, P; Coudert, S.; Caignaert, G.; Bois, G.; Ardizzon, G.)<br/></b><br/>Query date: 2017-05-06).
Abstract | BibTeX | Tags: Francis-type Reversible Turbine, Pump, Pump as Turbine, Rotor Stator Interaction
@inproceedings{pop00041,
title = {Rotor-stator interactions in a radial flow pump},
author = {Giorgio Pavesi and Giovanna Cavazzini and Patrick Dupont and Sebastien Coudert and Guy Caignaert and Gérard Bois and Guido Ardizzon},
year = {2007},
date = {2007-01-01},
urldate = {2007-01-01},
booktitle = {Proceedings of the 7th European Conference on Turbomachinery: Fluid Dynamics and Thermodynamics, ETC 2007},
abstract = {The paper refers to the analysis of interactions between the impeller and the vaned dif- fuser of a radial flow pump. It mainly focuses on the flow within one blade passage of a vaned diffuser in four operating conditions. The 2D/2C PIV technique was used to analyze the diffuser flow field in various measuring planes in the hub to shroud direction, for one relative impeller position in the diffuser frame. These experimental results were compared to numerical data obtained with the help of CFX computer code.},
note = {<b>From Duplicate 1 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, G; Cavazzini, G; Dupont, P; Coudert, S.; Caignaert, G.; Bois, G.; Ardizzon, G.)<br/></b><br/>Query date: 2017-05-06<br/><br/><b>From Duplicate 2 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, Giorgio; Cavazzini, Giovanna; Dupont, Patrick; Coudert, Sebastien; Caignaert, Guy; Bois, Gérard; Ardizzon, Guido)<br/></b><br/><b>From Duplicate 2 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, G; Cavazzini, G; Dupont, P; Coudert, S.; Caignaert, G.; Bois, G.; Ardizzon, G.)<br/>And Duplicate 3 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, G; Cavazzini, G; Dupont, P; Coudert, S.; Caignaert, G.; Bois, G.; Ardizzon, G.)<br/>And Duplicate 4 (<i>Rotor-stator interactions in a radial flow pump</i> - Pavesi, G; Cavazzini, G; Dupont, P; Coudert, S.; Caignaert, G.; Bois, G.; Ardizzon, G.)<br/></b><br/>Query date: 2017-05-06},
keywords = {Francis-type Reversible Turbine, Pump, Pump as Turbine, Rotor Stator Interaction},
pubstate = {published},
tppubtype = {inproceedings}
}
The paper refers to the analysis of interactions between the impeller and the vaned dif- fuser of a radial flow pump. It mainly focuses on the flow within one blade passage of a vaned diffuser in four operating conditions. The 2D/2C PIV technique was used to analyze the diffuser flow field in various measuring planes in the hub to shroud direction, for one relative impeller position in the diffuser frame. These experimental results were compared to numerical data obtained with the help of CFX computer code.
1999
Guido Ardizzon, Giorgio Pavesi
Analisi Sperimentale della Caratteristica Interna di una Turbomacchina ai Carichi Parziali Proceedings Article
In: MIS - MAC VI Metodi di Sperimentazione nelle Macchine, pp. 63-74, SGE - Padova, 1999.
Abstract | BibTeX | Tags: Losses, part load, Pump, Pump as Turbine, Turbine
@inproceedings{ArdizzonGPavesiG1999,
title = {Analisi Sperimentale della Caratteristica Interna di una Turbomacchina ai Carichi Parziali},
author = {Guido Ardizzon, Giorgio Pavesi},
year = {1999},
date = {1999-01-01},
urldate = {1999-01-01},
booktitle = {MIS - MAC VI Metodi di Sperimentazione nelle Macchine},
pages = {63-74},
publisher = {SGE - Padova},
abstract = {Direct and reverse operation of three radial flow turbomachines at part load conditions are investigated in order to evaluate the energy exchange between runner and fluid. Recirculation phenomena that occur at low flowrates interact with the blade passages with a net exchange momentum which has to be supplied by the impeller in pump mode, while reducing the one transmitted to the rotor by the fluid in turbine mode. Partial flow characteristic curves are also influenced in both operation modes. In order to highlight the role played by backward flows on the performances, the runnerfluid energy transfer has been evaluated from both velocity and power measurements. In particular, leakage and windage losses have been segregated and measured. The experimental results show that when recirculation phenomena occur within the runner, the energy exchange obtained from angular momentum equation only represents the work done by the driving motor on the discharge flowrate in pump mode. While it represents the net energy transferred to the rotor by the driving flowrate in reverse mode, that is the mechanical work available on the shaft when internal recirculation losses are taken into account.},
keywords = {Losses, part load, Pump, Pump as Turbine, Turbine},
pubstate = {published},
tppubtype = {inproceedings}
}
Direct and reverse operation of three radial flow turbomachines at part load conditions are investigated in order to evaluate the energy exchange between runner and fluid. Recirculation phenomena that occur at low flowrates interact with the blade passages with a net exchange momentum which has to be supplied by the impeller in pump mode, while reducing the one transmitted to the rotor by the fluid in turbine mode. Partial flow characteristic curves are also influenced in both operation modes. In order to highlight the role played by backward flows on the performances, the runnerfluid energy transfer has been evaluated from both velocity and power measurements. In particular, leakage and windage losses have been segregated and measured. The experimental results show that when recirculation phenomena occur within the runner, the energy exchange obtained from angular momentum equation only represents the work done by the driving motor on the discharge flowrate in pump mode. While it represents the net energy transferred to the rotor by the driving flowrate in reverse mode, that is the mechanical work available on the shaft when internal recirculation losses are taken into account.
Ardizzon, Guido; Pavesi, Giorgio
Funzionamento Inverso di una Pompa Centrifuga. Previsione delle Prestazioni e Confronto con i Dati Sperimentali Proceedings Article
In: 54° Congresso Nazionale ATI, pp. 1383-1395, SGE - Padova, 1999.
Abstract | BibTeX | Tags: PAT, Pump as Turbine
@inproceedings{Ardizzon1999a,
title = {Funzionamento Inverso di una Pompa Centrifuga. Previsione delle Prestazioni e Confronto con i Dati Sperimentali},
author = {Guido Ardizzon and Giorgio Pavesi},
year = {1999},
date = {1999-01-01},
urldate = {1999-01-01},
booktitle = {54° Congresso Nazionale ATI},
pages = {1383-1395},
publisher = {SGE - Padova},
abstract = {Direct and reverse operation of radial flow turbomachines is examined and a method suggested for the evaluation of reverse operation when performance characteristics in the direct mode are known. The theoretical results are checked against those obtained from tests on a number of machine configurations and compared with those predicted by current empirical formulations.},
keywords = {PAT, Pump as Turbine},
pubstate = {published},
tppubtype = {inproceedings}
}
Direct and reverse operation of radial flow turbomachines is examined and a method suggested for the evaluation of reverse operation when performance characteristics in the direct mode are known. The theoretical results are checked against those obtained from tests on a number of machine configurations and compared with those predicted by current empirical formulations.
1998
Ventrone, Giuseppe; Ardizzon, Guido; Pavesi, Giorgio
Flow Configurations in Centrifugal Pumps Used as Turbines Proceedings Article
In: 2nd International Minihydro Conference, pp. 5-8, 1998.
Abstract | BibTeX | Tags: PAT, Pump as Turbine
@inproceedings{VentroneG.1998,
title = {Flow Configurations in Centrifugal Pumps Used as Turbines},
author = {Giuseppe Ventrone and Guido Ardizzon and Giorgio Pavesi},
year = {1998},
date = {1998-01-01},
urldate = {1998-01-01},
booktitle = {2nd International Minihydro Conference},
issue = {september},
pages = {5-8},
abstract = {Direct and reverse operation of hydraulic machines can be interrelated by means of a theoretical expression that is instrumental in the prediction of turbine H-Q values from pump performance curves. Tests have been carried out on four machine configurations in order to verify the validity of the procedure. Results furnished by present method are finally compared with those predicted by current empirical relationships.},
keywords = {PAT, Pump as Turbine},
pubstate = {published},
tppubtype = {inproceedings}
}
Direct and reverse operation of hydraulic machines can be interrelated by means of a theoretical expression that is instrumental in the prediction of turbine H-Q values from pump performance curves. Tests have been carried out on four machine configurations in order to verify the validity of the procedure. Results furnished by present method are finally compared with those predicted by current empirical relationships.
