Pump-Jet Propulsion

Contacts

PhD Giorgio Pavesi

Associate professor
Group: TURBOMACHINERY

+39 049 827 6768

giorgio.pavesi@unipd.it

Orcid Profile

MSc Yunkai Zhou

PhD student
Group: TURBOMACHINERY

yunkai.zhou@studenti.unipd.it

Publications

2025

Zhou, Yunkai; Yuan, Jianping; Fu, Yanxia; Ye, Shirong; Pavesi, Giorgio; Cavazzini, Giovanna

Analysis of hydraulic loss of the pump-jet with accelerating and decelerating ducts via entropy generation theory Journal Article

In: Physics of Fluids, vol. 37, iss. 7, 2025, ISSN: 10897666.

Abstract | Links | BibTeX | Tags: Accelerating Decelerating Ducts, Duct, Entropy, Pump Jet

@article{Zhou2025,

title = {Analysis of hydraulic loss of the pump-jet with accelerating and decelerating ducts via entropy generation theory},

author = {Yunkai Zhou and Jianping Yuan and Yanxia Fu and Shirong Ye and Giorgio Pavesi and Giovanna Cavazzini},

doi = {10.1063/5.0273790},

issn = {10897666},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

journal = {Physics of Fluids},

volume = {37},

issue = {7},

publisher = {American Institute of Physics},

abstract = {Pump-jets serve as critical propulsion systems for underwater vehicles, directly impacting navigation safety and energy efficiency. Traditional pressure-drop analysis methods, while widely adopted, exhibit limitations in spatially resolving localized energy dissipation mechanisms. This study implements entropy generation theory to systematically evaluate irreversible energy losses in pump-jet, with particular emphasis on quantifying the spatial distribution and magnitude of hydraulic losses. Through rigorous numerical investigations of accelerating and decelerating duct configurations with varying camber and attack angles, comparative analyses of energy characteristics are conducted across distinct pump-jet components. The results demonstrate that entropy generation theory proves advantageous when assessing the energy characteristics of pump-jet. Compared to accelerating duct pump-jet, the stator and pre-stator of decelerating duct pump-jet absorb a larger share of hydraulic losses, demonstrating superior hydrodynamic performance. Flow characteristics reveal that the variation of f and α leads to the significant influence on the entropy production in the flow field, while the instability mechanism of impeller and stator trailing vortices also share prominent diversity. Thus, f and α can serve as core parameters to distinguish between accelerating and decelerating ducts. Selecting appropriate parameters based on different operating conditions can significantly enhance performance and safety. Overall, this study provides thermomechanical guidelines for performance optimization through strategic geometric parameter selection under diverse operational conditions.},

keywords = {Accelerating Decelerating Ducts, Duct, Entropy, Pump Jet},

pubstate = {published},

tppubtype = {article}

}

Close

Pump-jets serve as critical propulsion systems for underwater vehicles, directly impacting navigation safety and energy efficiency. Traditional pressure-drop analysis methods, while widely adopted, exhibit limitations in spatially resolving localized energy dissipation mechanisms. This study implements entropy generation theory to systematically evaluate irreversible energy losses in pump-jet, with particular emphasis on quantifying the spatial distribution and magnitude of hydraulic losses. Through rigorous numerical investigations of accelerating and decelerating duct configurations with varying camber and attack angles, comparative analyses of energy characteristics are conducted across distinct pump-jet components. The results demonstrate that entropy generation theory proves advantageous when assessing the energy characteristics of pump-jet. Compared to accelerating duct pump-jet, the stator and pre-stator of decelerating duct pump-jet absorb a larger share of hydraulic losses, demonstrating superior hydrodynamic performance. Flow characteristics reveal that the variation of f and α leads to the significant influence on the entropy production in the flow field, while the instability mechanism of impeller and stator trailing vortices also share prominent diversity. Thus, f and α can serve as core parameters to distinguish between accelerating and decelerating ducts. Selecting appropriate parameters based on different operating conditions can significantly enhance performance and safety. Overall, this study provides thermomechanical guidelines for performance optimization through strategic geometric parameter selection under diverse operational conditions.

Close

• doi:10.1063/5.0273790

Close

2023

Zhou, Yunkai; Pavesi, Giorgio; Yuan, Jianping; Fu, Yanxia; Gao, Quanlin

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 Journal Article

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}

}

Close

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.

Close

• doi:10.1016/j.oceaneng.2023.114733

Close

Zhou, Yunkai; Pavesi, Giorgio; Cavazzini, Giovanna; Yuan, Jianping; Fu, Yanxia; Gao, Quanlin

Comparative numerical investigation on flow characteristics of pump-jets with accelerating duct and decelerating duct Technical Report

2023.

Abstract | Links | BibTeX | Tags: Flow field, Hydrodynamic performance, Numerical simulation, Pump-jet

@techreport{Zhou2023b,

title = {Comparative numerical investigation on flow characteristics of pump-jets with accelerating duct and decelerating duct},

author = {Yunkai Zhou and Giorgio Pavesi and Giovanna Cavazzini and Jianping Yuan and Yanxia Fu and Quanlin Gao},

url = {https://ssrn.com/abstract=4374636},

year  = {2023},

date = {2023-01-01},

abstract = {The mutual interaction between the duct and components of pump-jet can induce significant effects on the overall flow properties and inner flow field. In order to compare the properties of pump-jets with accelerating and decelerating ducts and investigate the effects of duct profiles parameters of two different ducts on the flow characteristics, a detailed numerical analysis is implemented on the flow characteristics and interaction of the pump-jet with different duct profile parameters. Beforehand, the comparison of experiment and simulation of propeller VP1304 and the pump-jet under mooring conditions are adopted to validate numerical methodology. In this paper, five cambers f (f=0.5t, 0.25t, 0,-0.25t,-0.5t) and three angles of attack α (α= 4°, 0°,-4°) of duct profile, employed to distinguish accelerating and decelerating ducts, are considered carefully, focusing on the flow field information and propulsion performance. The results, including the comparison of single ducts with different f and α, and comparison of pump-jet with 2 types of ducts distinguished by different f and α, are exhibited. It shows 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. Compared with the change of α, the variation of f makes the internal evolution of the flow field more intuitive. Further results indicate that the maximum efficiency of pump-jet drops after the modest growth as the cambers decrease, whose location shift 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. It is advantageous for the high f to 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 = {Flow field, Hydrodynamic performance, Numerical simulation, Pump-jet},

pubstate = {published},

tppubtype = {techreport}

}

Close

The mutual interaction between the duct and components of pump-jet can induce significant effects on the overall flow properties and inner flow field. In order to compare the properties of pump-jets with accelerating and decelerating ducts and investigate the effects of duct profiles parameters of two different ducts on the flow characteristics, a detailed numerical analysis is implemented on the flow characteristics and interaction of the pump-jet with different duct profile parameters. Beforehand, the comparison of experiment and simulation of propeller VP1304 and the pump-jet under mooring conditions are adopted to validate numerical methodology. In this paper, five cambers f (f=0.5t, 0.25t, 0,-0.25t,-0.5t) and three angles of attack α (α= 4°, 0°,-4°) of duct profile, employed to distinguish accelerating and decelerating ducts, are considered carefully, focusing on the flow field information and propulsion performance. The results, including the comparison of single ducts with different f and α, and comparison of pump-jet with 2 types of ducts distinguished by different f and α, are exhibited. It shows 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. Compared with the change of α, the variation of f makes the internal evolution of the flow field more intuitive. Further results indicate that the maximum efficiency of pump-jet drops after the modest growth as the cambers decrease, whose location shift 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. It is advantageous for the high f to 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.

Close

• https://ssrn.com/abstract=4374636

Close

2022

Zhou, Yunkai; Pavesi, Giorgio; Yuan, Jianping; Fu, Yanxia

A Review on Hydrodynamic Performance and Design of Pump-Jet: Advances, Challenges and Prospects Journal Article

In: Journal of Marine Science and Engineering, vol. 10, iss. 10, 2022, ISSN: 20771312.

Abstract | Links | BibTeX | Tags: design, Flow field, Hydrodynamic performance, Pump-jet

@article{Zhou2022,

title = {A Review on Hydrodynamic Performance and Design of Pump-Jet: Advances, Challenges and Prospects},

author = {Yunkai Zhou and Giorgio Pavesi and Jianping Yuan and Yanxia Fu},

url = {https://www.mdpi.com/2077-1312/10/10/1514},

doi = {10.3390/jmse10101514},

issn = {20771312},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {Journal of Marine Science and Engineering},

volume = {10},

issue = {10},

publisher = {MDPI},

abstract = {A pump-jet, which is generally and widely adopted on underwater vehicles for applications from deep sea exploration to mine clearing, consists of a rotor, stator, and duct, with the properties of high critical speed, high propulsion efficiency, great anti-cavitation performance, and low radiated noise. The complex interaction of the flow field between the various components and the high degree of coupling with the appendage result in the requirements of in-depth research on the hydrodynamic performance and flow field for application and design. Due to the initial application on the military field and complicated structure, there is scant literature in the evaluation of pump-jet performance and optimal design. This paper, in a comprehensive and specialized way, summarizes the pump-jet hydrodynamic performance, noise performance, and flow field characteristics involving cavitation erosion and vortices properties of tip-clearance, the interaction between the rotor and the stator and the wake field, as well as the optimal design of the pump-jet. The merits and applications range of numerical and experimental methods are overviewed as well as the design method. It also concludes the main challenges faced in practical applications and proposes a vision for future research. It was found that the compact structure and complex internal and external flow field make the pump-jet significantly different, also leading to higher performance. As the focus of cavitation research, vortices interact with the complex structure of the pump-jet, leading to instabilities of the flow field, such as vibration, radiated noise, and cavitation erosion. The effective approaches are adopted to reduce radiated pump-jet with minimal influence on the hydrodynamic performance, such as eliminating the tip clearance and installing the sawtooth duct. Advanced optimal technology can achieve high performance, cavitation performance, and acoustic performance, possessing good prospects. Further developments in investigation and the application of pump-jets in the multidisciplinary integration of fluid dynamics, acoustics, materials, chemistry, and bionics should be the main focus in future research.},

keywords = {design, Flow field, Hydrodynamic performance, Pump-jet},

pubstate = {published},

tppubtype = {article}

}

Close

A pump-jet, which is generally and widely adopted on underwater vehicles for applications from deep sea exploration to mine clearing, consists of a rotor, stator, and duct, with the properties of high critical speed, high propulsion efficiency, great anti-cavitation performance, and low radiated noise. The complex interaction of the flow field between the various components and the high degree of coupling with the appendage result in the requirements of in-depth research on the hydrodynamic performance and flow field for application and design. Due to the initial application on the military field and complicated structure, there is scant literature in the evaluation of pump-jet performance and optimal design. This paper, in a comprehensive and specialized way, summarizes the pump-jet hydrodynamic performance, noise performance, and flow field characteristics involving cavitation erosion and vortices properties of tip-clearance, the interaction between the rotor and the stator and the wake field, as well as the optimal design of the pump-jet. The merits and applications range of numerical and experimental methods are overviewed as well as the design method. It also concludes the main challenges faced in practical applications and proposes a vision for future research. It was found that the compact structure and complex internal and external flow field make the pump-jet significantly different, also leading to higher performance. As the focus of cavitation research, vortices interact with the complex structure of the pump-jet, leading to instabilities of the flow field, such as vibration, radiated noise, and cavitation erosion. The effective approaches are adopted to reduce radiated pump-jet with minimal influence on the hydrodynamic performance, such as eliminating the tip clearance and installing the sawtooth duct. Advanced optimal technology can achieve high performance, cavitation performance, and acoustic performance, possessing good prospects. Further developments in investigation and the application of pump-jets in the multidisciplinary integration of fluid dynamics, acoustics, materials, chemistry, and bionics should be the main focus in future research.

Close

• https://www.mdpi.com/2077-1312/10/10/1514
• doi:10.3390/jmse10101514

Close