2024
Zhang, Xiaowen; Pavesi, Giorgio; Xu, Zhe; Song, Xijie; Tang, Fangping
Phase classification and transient effects of the start-up process of multi-functional pump station in pump mode Journal Article
In: Journal of Energy Storage, vol. 100, 2024, ISSN: 2352152X.
Abstract | Links | BibTeX | Tags: Multi-functional pump station, Phase classification, Pump Mode, Start-up process, Steady-state full characteristic experiment, Transient effect
@article{Zhang2024d,
title = {Phase classification and transient effects of the start-up process of multi-functional pump station in pump mode},
author = {Xiaowen Zhang and Giorgio Pavesi and Zhe Xu and Xijie Song and Fangping Tang},
doi = {10.1016/j.est.2024.113517},
issn = {2352152X},
year = {2024},
date = {2024-01-01},
journal = {Journal of Energy Storage},
volume = {100},
publisher = {Elsevier Ltd},
abstract = {In the context of achieving the goal of carbon neutrality, multi-functional pump stations (MFPS) have been greatly developed as a new energy system in recent years. The MFPS can operate in forward direction in pump mode to pump water and in turbine mode in reverse direction to generate electricity. At present, the instability of the MFPS during start-up process (SUP) in pump mode has become the key to restricting the operating life and further development of MFPS. In this paper, based on the motion characteristics of the pump and the cut-off facility (COF), the SUP of the MFPS in pump mode is clearly classified. In order to reveal the transient effect during the SUP, the steady-state full characteristic experiment (SFCE) of the pump was carried out. The occurrence phase of the transient effect during the SUP is analyzed, and the deviation between the steady-state external characteristics and the transient characteristics is revealed. In this study, the evaluation formula of the start-up completion degree (SUCD) of the MFPS in pump mode is proposed for the first time, and the evaluation and identification of the start-up progress at different phases are completed. The results show that the water flow in the system is in a reverse flow state in the Phase I. The SUCD of Phase I is 17 %. In the Phase II, The high-speed jet flow in the pump flows to the inlet of the guide vane (GV), which gradually changes the mainstream direction in the GV. A certain vortex structure can be observed at the exit of the flap gate (FG). The SUCD of Phase II is 61 %. In the Phase I and II, the dimensionless head of transient simulation is much larger than that of SFCE. In the Phase III, the flow state in the impeller will gradually stabilize. The transient effect disappears and the pressure fluctuation intensity decreases. The SUCD of Phase III is 93 %. In the Phase IV, the separation vortex that persists from Phase I-III at the tail of the GV blades disappears. The diversion capacity at the gate increases, and significant annular flow can be observed near the FG.},
keywords = {Multi-functional pump station, Phase classification, Pump Mode, Start-up process, Steady-state full characteristic experiment, Transient effect},
pubstate = {published},
tppubtype = {article}
}
In the context of achieving the goal of carbon neutrality, multi-functional pump stations (MFPS) have been greatly developed as a new energy system in recent years. The MFPS can operate in forward direction in pump mode to pump water and in turbine mode in reverse direction to generate electricity. At present, the instability of the MFPS during start-up process (SUP) in pump mode has become the key to restricting the operating life and further development of MFPS. In this paper, based on the motion characteristics of the pump and the cut-off facility (COF), the SUP of the MFPS in pump mode is clearly classified. In order to reveal the transient effect during the SUP, the steady-state full characteristic experiment (SFCE) of the pump was carried out. The occurrence phase of the transient effect during the SUP is analyzed, and the deviation between the steady-state external characteristics and the transient characteristics is revealed. In this study, the evaluation formula of the start-up completion degree (SUCD) of the MFPS in pump mode is proposed for the first time, and the evaluation and identification of the start-up progress at different phases are completed. The results show that the water flow in the system is in a reverse flow state in the Phase I. The SUCD of Phase I is 17 %. In the Phase II, The high-speed jet flow in the pump flows to the inlet of the guide vane (GV), which gradually changes the mainstream direction in the GV. A certain vortex structure can be observed at the exit of the flap gate (FG). The SUCD of Phase II is 61 %. In the Phase I and II, the dimensionless head of transient simulation is much larger than that of SFCE. In the Phase III, the flow state in the impeller will gradually stabilize. The transient effect disappears and the pressure fluctuation intensity decreases. The SUCD of Phase III is 93 %. In the Phase IV, the separation vortex that persists from Phase I-III at the tail of the GV blades disappears. The diversion capacity at the gate increases, and significant annular flow can be observed near the FG.
2018
Yang, Jun; Pavesi, Giorgio; Liu, Xiaohua; Xie, Tian; Liu, Jun
Unsteady flow characteristics regarding hump instability in the first stage of a multistage pump-turbine in pump mode Journal Article
In: Renewable Energy, vol. 127, pp. 377-385, 2018, ISSN: 09601481.
Abstract | Links | BibTeX | Tags: Hump instability, Pump as Turbine, Pump Mode, Return channel, Unsteady Flow
@article{Yang2018b,
title = {Unsteady flow characteristics regarding hump instability in the first stage of a multistage pump-turbine in pump mode},
author = {Jun Yang and Giorgio Pavesi and Xiaohua Liu and Tian Xie and Jun Liu},
url = {https://doi.org/10.1016/j.renene.2018.04.069 https://linkinghub.elsevier.com/retrieve/pii/S0960148118304774},
doi = {10.1016/j.renene.2018.04.069},
issn = {09601481},
year = {2018},
date = {2018-01-01},
journal = {Renewable Energy},
volume = {127},
pages = {377-385},
publisher = {Elsevier Ltd},
abstract = {This article reports the fluid-dynamical analyses of unsteady flow in the first stage of a multistage pump-turbine where hump instability occurs. This stage can be seen as a centrifugal pump with multistage guide vanes in pump mode. Experimental and numerical approaches are adopted to contribute the understanding of the highly complex flow regime inner the test pump. In the experimental test, both dynamic pressure measurement and flow visualization techniques are adopted. A commercial code with detached eddy simulation (DES) model is used to compute the flow regime. The frequency analysis indicates that two unsteady flow patterns with a constant frequency occur in the hump instability region. The numerical and experimental unsteady flow fields are analysed to study the fluid-dynamical features of these unsteady patterns, in order to investigate the origin and reveal their contributions to the hump instability.},
keywords = {Hump instability, Pump as Turbine, Pump Mode, Return channel, Unsteady Flow},
pubstate = {published},
tppubtype = {article}
}
This article reports the fluid-dynamical analyses of unsteady flow in the first stage of a multistage pump-turbine where hump instability occurs. This stage can be seen as a centrifugal pump with multistage guide vanes in pump mode. Experimental and numerical approaches are adopted to contribute the understanding of the highly complex flow regime inner the test pump. In the experimental test, both dynamic pressure measurement and flow visualization techniques are adopted. A commercial code with detached eddy simulation (DES) model is used to compute the flow regime. The frequency analysis indicates that two unsteady flow patterns with a constant frequency occur in the hump instability region. The numerical and experimental unsteady flow fields are analysed to study the fluid-dynamical features of these unsteady patterns, in order to investigate the origin and reveal their contributions to the hump instability.
Yang, Jun; Xie, Tian; Giorgio, Pavesi; Liu, Xiaohua; Liu, Jun
Numerical study on rotating characteristics of unsteady flow inner pump-turbine in pump mode Journal Article
In: International Journal of Fluid Machinery and Systems, vol. 11, iss. 3, pp. 224-233, 2018, ISSN: 18829554.
Abstract | Links | BibTeX | Tags: Pump as Turbine, Pump Mode, Rotating characteristics, Unsteady Flow
@article{Yang2018a,
title = {Numerical study on rotating characteristics of unsteady flow inner pump-turbine in pump mode},
author = {Jun Yang and Tian Xie and Pavesi Giorgio and Xiaohua Liu and Jun Liu},
doi = {10.5293/IJFMS.2018.11.3.224},
issn = {18829554},
year = {2018},
date = {2018-01-01},
journal = {International Journal of Fluid Machinery and Systems},
volume = {11},
issue = {3},
pages = {224-233},
abstract = {In order to investigate the formation of the rotating stall in diffuser of pump-turbine in pump mode, the unsteady flow with radial rotating characteristics before the occurrence of rotating stall are investigated by detached eddy simulation. The results indicate that the unsteady flow patterns which occur in the return channel both at full and part load conditions contain two periodical disturbances with frequencies St≈0.042 and St≈0.085, and the Strouhal number St is frequency normalized by blade passing frequency of impeller. These periodical disturbances not only influence the pressure field but also cause rotating characteristics in diffuser channels. One is composed of 4 cells propagating at 0.073 times of impeller rotating speed. The other one is made up of 3 rotating cells with 0.2 times of backward impeller rotating speed. Meanwhile, there are two radial rotating characteristics which contribute the spectra peak at blade pass frequency in diffuser. One is at the inlet of diffuser propagating at impeller rotating speed with 7 cells, and the other one contains 4 cells with about 1.75 backward impeller rotating speed.},
keywords = {Pump as Turbine, Pump Mode, Rotating characteristics, Unsteady Flow},
pubstate = {published},
tppubtype = {article}
}
In order to investigate the formation of the rotating stall in diffuser of pump-turbine in pump mode, the unsteady flow with radial rotating characteristics before the occurrence of rotating stall are investigated by detached eddy simulation. The results indicate that the unsteady flow patterns which occur in the return channel both at full and part load conditions contain two periodical disturbances with frequencies St≈0.042 and St≈0.085, and the Strouhal number St is frequency normalized by blade passing frequency of impeller. These periodical disturbances not only influence the pressure field but also cause rotating characteristics in diffuser channels. One is composed of 4 cells propagating at 0.073 times of impeller rotating speed. The other one is made up of 3 rotating cells with 0.2 times of backward impeller rotating speed. Meanwhile, there are two radial rotating characteristics which contribute the spectra peak at blade pass frequency in diffuser. One is at the inlet of diffuser propagating at impeller rotating speed with 7 cells, and the other one contains 4 cells with about 1.75 backward impeller rotating speed.
2016
Yang, Jun; Yuan, Shouqi; Pavesi, Giorgio; Li, Chun; Ye, Zhou; Shouqi, Yuan
Study of Hump Instability Phenomena in Pump Turbine at Large Partial Flow Conditions on Pump Mode Journal Article
In: Journal of Mechanical Engineering, vol. 52, iss. 24, pp. 170, 2016, ISSN: 0577-6686.
Abstract | Links | BibTeX | Tags: Francis-type Reversible Turbine, Hump instability, large partial flow conditions, Pump, Pump, Pump as Turbine, Pump Mode, unsteady flow pattern
@article{Yang2016,
title = {Study of Hump Instability Phenomena in Pump Turbine at Large Partial Flow Conditions on Pump Mode},
author = {Jun Yang and Shouqi Yuan and Giorgio Pavesi and Chun Li and Zhou Ye and Yuan Shouqi},
url = {http://www.cjmenet.com.cn/Jwk_jxgcxb/CN/10.3901/JME.2016.24.170},
doi = {10.3901/JME.2016.24.170},
issn = {0577-6686},
year = {2016},
date = {2016-01-01},
urldate = {2016-01-01},
journal = {Journal of Mechanical Engineering},
volume = {52},
issue = {24},
pages = {170},
abstract = {For middle- and high-specific speed pump turbines, the hump instability appearing at large partial flow conditions seriously restricts its stable operation range. These phenomena relate closely to the inner unsteady flow in pump turbine. We investigate the characterization of pressure fluctuation and the mechanism of unsteady flow by an experimental and numerical study of the unsteady flow occurring among the adjustable blades. For pump working at either full or part load conditions, two kinds of periodic pressure pulsations in the diffuser vane have been observed and analyzed. A hump instability appears only when the actual flow rate of head curve is 0.45-0.75 times of the designed value, and our frequency analysis further shows that its appearance is closely related to the two above pressure fluctuations.},
keywords = {Francis-type Reversible Turbine, Hump instability, large partial flow conditions, Pump, Pump, Pump as Turbine, Pump Mode, unsteady flow pattern},
pubstate = {published},
tppubtype = {article}
}
For middle- and high-specific speed pump turbines, the hump instability appearing at large partial flow conditions seriously restricts its stable operation range. These phenomena relate closely to the inner unsteady flow in pump turbine. We investigate the characterization of pressure fluctuation and the mechanism of unsteady flow by an experimental and numerical study of the unsteady flow occurring among the adjustable blades. For pump working at either full or part load conditions, two kinds of periodic pressure pulsations in the diffuser vane have been observed and analyzed. A hump instability appears only when the actual flow rate of head curve is 0.45-0.75 times of the designed value, and our frequency analysis further shows that its appearance is closely related to the two above pressure fluctuations.
