2025
Zhang, Xiaowen; Pavesi, Giorgio; Hu, Chongyang; Song, Xijie; Tang, Fangping
Impact of the motion effect of the cutoff facility on the dynamic energy loss of the prototype axial flow pump system during the startup process Journal Article
In: Physics of Fluids, vol. 37, iss. 1, 2025, ISSN: 10897666.
Abstract | Links | BibTeX | Tags: Axial Pump, Energy loss, Pump, startup
@article{Zhang2025,
title = {Impact of the motion effect of the cutoff facility on the dynamic energy loss of the prototype axial flow pump system during the startup process},
author = {Xiaowen Zhang and Giorgio Pavesi and Chongyang Hu and Xijie Song and Fangping Tang},
doi = {10.1063/5.0250407},
issn = {10897666},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
journal = {Physics of Fluids},
volume = {37},
issue = {1},
publisher = {American Institute of Physics},
abstract = {Large pumping systems have emerged as one of the primary areas of energy consumption. During the startup process (SUP) of the axial flow pump system (AFPS), a complex interaction unfolds involving the motion of the cutoff facilities (COF), the acceleration of the pump, and the phenomenon of energy dissipation. The kinematic characteristics of the COF significantly influence the flow patterns, dynamic loads, and energy transfer experienced by the system. This study investigates the energy dissipation mechanism of a prototype AFPS (PAFPS) during SUP, utilizing a combination of experiments on engine starting characteristics, computational fluid dynamics, and in-field measurements of the PAFPS. Two COF motion modes are compared, revealing that accelerated gate opening improves transition efficiency and reduces energy consumption. Key findings highlight that accelerated gate motion minimizes turbulence-induced losses near the COF exit and suppresses high entropy production regions in the impeller domain, leading to smoother and more energy-efficient operations. These insights offer actionable strategies to enhance pump system performance during SUP.},
keywords = {Axial Pump, Energy loss, Pump, startup},
pubstate = {published},
tppubtype = {article}
}
Large pumping systems have emerged as one of the primary areas of energy consumption. During the startup process (SUP) of the axial flow pump system (AFPS), a complex interaction unfolds involving the motion of the cutoff facilities (COF), the acceleration of the pump, and the phenomenon of energy dissipation. The kinematic characteristics of the COF significantly influence the flow patterns, dynamic loads, and energy transfer experienced by the system. This study investigates the energy dissipation mechanism of a prototype AFPS (PAFPS) during SUP, utilizing a combination of experiments on engine starting characteristics, computational fluid dynamics, and in-field measurements of the PAFPS. Two COF motion modes are compared, revealing that accelerated gate opening improves transition efficiency and reduces energy consumption. Key findings highlight that accelerated gate motion minimizes turbulence-induced losses near the COF exit and suppresses high entropy production regions in the impeller domain, leading to smoother and more energy-efficient operations. These insights offer actionable strategies to enhance pump system performance during SUP.
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.
