2023
Zhou, Yunkai; Pavesi, Giorgio; Yuan, Jianping; Fu, Yanxia; Gao, Quanlin
In: Ocean Engineering, vol. 281, 2023, ISSN: 00298018.
Abstract | Links | BibTeX | Tags: Duct profile parameters, Flow characteristics, Hydrodynamic performance, Numerical simulation, Pump-jet
@article{Zhou2023,
title = {Effects of duct profile parameters on flow characteristics of pump-jet: A numerical analysis on accelerating and decelerating ducts distinguished by cambers and angles of attack},
author = {Yunkai Zhou and Giorgio Pavesi and Jianping Yuan and Yanxia Fu and Quanlin Gao},
doi = {10.1016/j.oceaneng.2023.114733},
issn = {00298018},
year = {2023},
date = {2023-01-01},
journal = {Ocean Engineering},
volume = {281},
publisher = {Elsevier Ltd},
abstract = {The aim of this study is to investigate the effects of duct profile parameters cambers and angles of attack that distinguish accelerating and decelerating ducts on the flow characteristics of pump-jet. A detailed numerical analysis is carried out to compare the properties of pump-jets with different cambers and attack angles, and to explore the mutual interaction between the duct and components of pump-jet. Beforehand, the numerical methodology is validated by comparing the experiment and simulation results of the pump-jet under mooring conditions and propeller VP1304. Five cambers (f = 0.5t, 0.25t, 0, −0.25t, −0.5t) and three attack angles (α = 4°, 0°, −4°) of duct profile are considered carefully to distinguish accelerating and decelerating ducts, focusing on the propulsion performance and flow field information. The results show that the flow velocity at the outlet of the accelerating ducts is significantly higher compared to the inlet velocity, as opposed to the phenomenon produced by decelerating ducts. The variation of camber makes the internal evolution of the flow field more intuitive compared with the change of angles of attack. Further results indicate that the maximum efficiency of pump-jet drops after the modest growth as the cambers decrease, whose location shifts towards the lower advance coefficient J. The alteration of α leads to making the trend more direct and apparent for the decelerating and accelerating ducts. The high f is advantageous for the cavitation resistance of inside components, like rotor blades and stator blades. The impacts of changing α on the distribution of pressure in pump-jets with accelerating and decelerating ducts are more prominent than changing f. Moreover, the effects of both variations of f and α on the circumferential distributions of the velocity components are prominent, while there are still significant differences between these changes. Additionally, the velocity distribution at the inlet of pump-jets with decelerating ducts is higher than that at the outlet, and the velocity distribution of pump-jets with accelerating ducts presents the opposite pattern.},
keywords = {Duct profile parameters, Flow characteristics, Hydrodynamic performance, Numerical simulation, Pump-jet},
pubstate = {published},
tppubtype = {article}
}
The aim of this study is to investigate the effects of duct profile parameters cambers and angles of attack that distinguish accelerating and decelerating ducts on the flow characteristics of pump-jet. A detailed numerical analysis is carried out to compare the properties of pump-jets with different cambers and attack angles, and to explore the mutual interaction between the duct and components of pump-jet. Beforehand, the numerical methodology is validated by comparing the experiment and simulation results of the pump-jet under mooring conditions and propeller VP1304. Five cambers (f = 0.5t, 0.25t, 0, −0.25t, −0.5t) and three attack angles (α = 4°, 0°, −4°) of duct profile are considered carefully to distinguish accelerating and decelerating ducts, focusing on the propulsion performance and flow field information. The results show that the flow velocity at the outlet of the accelerating ducts is significantly higher compared to the inlet velocity, as opposed to the phenomenon produced by decelerating ducts. The variation of camber makes the internal evolution of the flow field more intuitive compared with the change of angles of attack. Further results indicate that the maximum efficiency of pump-jet drops after the modest growth as the cambers decrease, whose location shifts towards the lower advance coefficient J. The alteration of α leads to making the trend more direct and apparent for the decelerating and accelerating ducts. The high f is advantageous for the cavitation resistance of inside components, like rotor blades and stator blades. The impacts of changing α on the distribution of pressure in pump-jets with accelerating and decelerating ducts are more prominent than changing f. Moreover, the effects of both variations of f and α on the circumferential distributions of the velocity components are prominent, while there are still significant differences between these changes. Additionally, the velocity distribution at the inlet of pump-jets with decelerating ducts is higher than that at the outlet, and the velocity distribution of pump-jets with accelerating ducts presents the opposite pattern.
2018
Pavesi, Giorgio; Xie, Zhanshan; Zheng, Yuan; Ge, Xinfeng; Mao, Xiu-li; Zheng, Yuan
A new method of dynamic mesh used in continuous guide vane closure of a reversible pump-turbine in generating mode Journal Article
In: Journal of Hydrodynamics, vol. 30, iss. 5, pp. 828-836, 2018, ISSN: 1001-6058.
Abstract | Links | BibTeX | Tags: Dynamic Mesh, Flow characteristics, Francis-type Reversible Turbine, Guide Vane Closure
@article{Pavesi2018b,
title = {A new method of dynamic mesh used in continuous guide vane closure of a reversible pump-turbine in generating mode},
author = {Giorgio Pavesi and Zhanshan Xie and Yuan Zheng and Xinfeng Ge and Xiu-li Mao and Yuan Zheng},
doi = {10.1007/s42241-018-0146-y},
issn = {1001-6058},
year = {2018},
date = {2018-01-01},
urldate = {2018-01-01},
journal = {Journal of Hydrodynamics},
volume = {30},
issue = {5},
pages = {828-836},
publisher = {Springer Nature},
abstract = {In this paper, a new method of dynamic mesh based on two functional controls is used in continuous guide vane closure, three-dimensional numerical simulation is carried out to investigate the transient flow characteristics for a Francis-type reversible pump-turbine under turbine mode in the load regulation scenario. Detached Eddy Simulation (DES) turbulent model is adopted. The transient flow characteristics during the closure of guide vanes are illustrated by analyzing the signals of mass flow, torque and pressure fluctuations in frequency and time-frequency domains. It is shown by simulating results that continuously assessment of the transient flow characteristics during guide vane closure is available by using the new method of dynamic mesh. Furthermore, the flow field analysis contains both the onset and the development of unsteady phenomena progressively based on an organized guide vane closure law. The flow pattern in return channel maintains a relatively stable flow field before the last stage of closure, compared with the unstable flow field in other domains. To identify the fluid-dynamical conditions causing unit variation, the influence of three-dimensional unsteady flow structures in passage is analyzed and its evolution during this transient process is characterized fluid-dynamically and spectrally.},
keywords = {Dynamic Mesh, Flow characteristics, Francis-type Reversible Turbine, Guide Vane Closure},
pubstate = {published},
tppubtype = {article}
}
In this paper, a new method of dynamic mesh based on two functional controls is used in continuous guide vane closure, three-dimensional numerical simulation is carried out to investigate the transient flow characteristics for a Francis-type reversible pump-turbine under turbine mode in the load regulation scenario. Detached Eddy Simulation (DES) turbulent model is adopted. The transient flow characteristics during the closure of guide vanes are illustrated by analyzing the signals of mass flow, torque and pressure fluctuations in frequency and time-frequency domains. It is shown by simulating results that continuously assessment of the transient flow characteristics during guide vane closure is available by using the new method of dynamic mesh. Furthermore, the flow field analysis contains both the onset and the development of unsteady phenomena progressively based on an organized guide vane closure law. The flow pattern in return channel maintains a relatively stable flow field before the last stage of closure, compared with the unstable flow field in other domains. To identify the fluid-dynamical conditions causing unit variation, the influence of three-dimensional unsteady flow structures in passage is analyzed and its evolution during this transient process is characterized fluid-dynamically and spectrally.
