Advancement in the Multiphase Flow in Fluid Machinery

A special issue of Journal of Marine Science and Engineering (ISSN 2077-1312). This special issue belongs to the section "Ocean Engineering".

Deadline for manuscript submissions: closed (20 February 2024) | Viewed by 9871

Special Issue Editors

Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
Interests: complex flow and vortex dynamics in pump turbine
Special Issues, Collections and Topics in MDPI journals
School of Naval Architecture & Ocean Engineering, Huazhong University of Science and Technology University, Hubei, China
Interests: fluid mechanics; vibration and noise control
Center for Industrial Diagnosis and Fluid Dynamics, Polytechnic University of Catalonia, 08028 Barcelona, Spain
Interests: fatigue failures; erosion and wear; signal processing; rotor systems; modal analysis; resonance problems; vibrations in hydraulic machinery
Special Issues, Collections and Topics in MDPI journals
S.C.I. Energy, Future Energy Research Institute, Seidengasse 17, 8706 Zurich, Switzerland
Interests: renewable energy; multiphysics coupling investigation; turbomachinery; simulation and measurement
Special Issues, Collections and Topics in MDPI journals
State Key Laboratory of Hydro Science and Engineering & Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
Interests: condition monitoring; fault diagnosis; prognosis of hydraulic machinery; numerical simulation and field test
College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou 225100, China
Interests: pump; water jet propulsion; pumping station; CFD; hydraulic machinery; model test

Special Issue Information

Dear Colleagues,

Fluid machinery parts (such as pumps, water turbines, marine propellers) are important components to the overall functionality of the machines that rely on them. During the operation of the unit, due to the variety of water flow patterns and working conditions, there will be various multi-phase flows in the unit, such as gas flow, sand and gas flow, cavitation, vortex, etc., each of which will seriously affect the safe and stable operation of the unit. It is necessary to carry out relevant research to ensure the stability and safety of the operation of units. We welcome scholars to contribute to this Special Issue to promote their research into the complex multiphase flow in fluid machinery. This Special Issue covers, but is not limited to, a wide range of topics, including:

  • New methods and models for numerical simulation of multiphase flow
  • New experiment methods and equipment for multiphase flow research
  • Cavitation vortex flow in hydraulic machinery
  • Gas–liquid–solid three-phase flow of sediment laden water flow
  • Multiphase flow in marine propellers

Dr. Xijie Song
Dr. Zhenwei Huang
Dr. Alexandre Presas
Dr. Xingxing Huang
Dr. Weiqiang Zhao
Dr. Weixuan Jiao
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Marine Science and Engineering is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • multiphase flow
  • vortex
  • cavitation
  • numerical simulation
  • experiments
  • pumps
  • hydraulic turbines
  • marine propellers

Published Papers (9 papers)

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Research

13 pages, 5492 KiB  
Article
A Comparative Study on the Cam Relationship for the Optimal Vibration and Efficiency of a Kaplan Turbine
by Sen Deng, Weiqiang Zhao, Tianbao Huang, Ming Xia and Zhengwei Wang
J. Mar. Sci. Eng. 2024, 12(2), 241; https://doi.org/10.3390/jmse12020241 - 30 Jan 2024
Viewed by 621
Abstract
Kaplan turbines are generally used in working conditions with a high flow and low head. These are a type of axial-flow hydro turbine that can adjust the opening of the guide vanes and blades simultaneously in order to achieve higher efficiency under a [...] Read more.
Kaplan turbines are generally used in working conditions with a high flow and low head. These are a type of axial-flow hydro turbine that can adjust the opening of the guide vanes and blades simultaneously in order to achieve higher efficiency under a wider range of loads. Different combinations of the opening of the guide vanes and blades (cam relationship) will lead to changes in the efficiency of the turbine unit as well as its vibration characteristics. A bad cam relationship will cause the low efficiency or unstable operation of the turbine. In this study, the relative efficiency and vibration of a large-scale Kaplan turbine with 200 MW output were tested with different guide vane and blade openings. The selection of the cam relationship curve for both optimal efficiency and optimal vibration is discussed. Compared with the cam relationship given by the model test, the prototype cam relationship improves the efficiency and reduces the vibration level. Compared to the optimal efficiency cam relationship, the optimal vibration cam relationship reduces the efficiency of the machine by 1% to 2%, while with the optimal efficiency cam relationship, the vibration of the unit increases significantly. This research provides guidance for the optimization of the regulation of a large adjustable-blade Kaplan turbine unit and improves the overall economic benefits and safety performance of the Kaplan turbine power station. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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14 pages, 5805 KiB  
Article
Reduced Order Data-Driven Analysis of Cavitating Flow over Hydrofoil with Machine Learning
by Weilong Guang, Peng Wang, Jinshuai Zhang, Linjuan Yuan, Yue Wang, Guang Feng and Ran Tao
J. Mar. Sci. Eng. 2024, 12(1), 148; https://doi.org/10.3390/jmse12010148 - 12 Jan 2024
Viewed by 587
Abstract
Predicting the flow situation of cavitation owing to its high-dimensional nonlinearity has posed great challenges. To address these challenges, this study presents a novel reduced order modeling (ROM) method to accurately analyze and predict cavitation flow fields under different conditions. The proposed ROM [...] Read more.
Predicting the flow situation of cavitation owing to its high-dimensional nonlinearity has posed great challenges. To address these challenges, this study presents a novel reduced order modeling (ROM) method to accurately analyze and predict cavitation flow fields under different conditions. The proposed ROM decomposes the flow field into linearized low-order modes while maintaining its accuracy and effectively reducing its dimensionality. Specifically, this study focuses on predicting cavitation on the Clark-Y hydrofoil using a combination of numerical simulation, proper orthogonal decomposition (POD), and neural networks. By analyzing different cavitation conditions, the results revealed that the POD method effectively reduces the order of the cavity flow field while achieving excellent flow field reconstruction. Notably, the zeroth- and first-order modes are associated with attachment cavitation, while the second-, third- and fourth-order modes correspond to cavitation shedding. Additionally, the fifth- and sixth-order modes along the hydrofoil surface are associated with the backward jet flow. To predict the conditions of high-energy modes, the neural network proved to be more effective, exhibiting excellent performance in stable attached cavitation. However, for cloud cavitation, the accuracy of the neural network model requires further improvement. This study not only introduces a novel approach for predicting cavitation flow fields but also highlights new challenges that will require continuous attention in future research endeavors. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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22 pages, 4576 KiB  
Article
Analysis of Stress–Strain Characteristics and Signal Coherence of Low-Specific-Speed Impeller Based on Fluid–Structure Interaction
by Fengquan Qiao, Yi Sun, Di Zhu, Mingkun Fang, Fangfang Zhang, Ran Tao and Ruofu Xiao
J. Mar. Sci. Eng. 2024, 12(1), 2; https://doi.org/10.3390/jmse12010002 - 19 Dec 2023
Viewed by 540
Abstract
In this study, an analysis of a low-specific-speed pump is carried out based on the methods of one-way and two-way fluid–structure interactions (FSIs). This study analyzes the influence of FSIs on the internal flow field and external characteristics of the pump. Utilizing a [...] Read more.
In this study, an analysis of a low-specific-speed pump is carried out based on the methods of one-way and two-way fluid–structure interactions (FSIs). This study analyzes the influence of FSIs on the internal flow field and external characteristics of the pump. Utilizing a two-way FSI, the signal coherence analysis method is employed to analyze the coherence of signals between the flow field and the structural field. Addressing the issue of a lack of a connection between the two signals, this study bridges a gap in the existing research. The results indicate that different interaction methods have certain influences on impeller stress and deformation. However, in both coupling modes, the maximum deformation and the maximum equivalent stress have the same distribution position. The head error obtained using the two-way coupling method is lower than that of the uncoupled results, which indicates that the two-way FSI calculation results are closer to the experimental results. The pressure pulsation signals at the interface of the impeller and volute exhibit strong coherence with the structural field signals. For low-specific-speed centrifugal pumps, establishing a clear connection between the flow field signals and structural field signals will help guide further optimization of their performance through design. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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14 pages, 3280 KiB  
Article
Comparative Study on Numerical Calculation of Modal Characteristics of Pump-Turbine Shaft System
by Xuyang Liu, Jiayang Pang, Lei Li, Weiqiang Zhao, Yupeng Wang, Dandan Yan, Lingjiu Zhou and Zhengwei Wang
J. Mar. Sci. Eng. 2023, 11(11), 2068; https://doi.org/10.3390/jmse11112068 - 29 Oct 2023
Cited by 1 | Viewed by 812
Abstract
Because a pump-turbine mainly undertakes the role of energy conversion and pumped storage in the field of hydropower engineering, the complex transition process and frequent conversion between different working conditions lead to the increase in the stress and strain of core components such [...] Read more.
Because a pump-turbine mainly undertakes the role of energy conversion and pumped storage in the field of hydropower engineering, the complex transition process and frequent conversion between different working conditions lead to the increase in the stress and strain of core components such as the unit shaft system, and even cause resonance phenomena. Based on ANSYS finite element numerical calculation software, this paper adopts the acoustic fluid–structure coupling method to study the influence of the shaft of the pump-turbine on the dynamic characteristics of the runner. At the same time, the paper analyses the influence of different contact modes between the runner and the shaft on the modal characteristics of the shaft system. The numerical simulation results have shown that the runner is affected by the added mass of the water. The natural frequency reduction rate of each order of wet modal is ranged from 19% to 64%. The main shaft has a greater influence on the simplification of the shaft system calculation method. The type of contact surface between the main shaft and the runner has a smaller influence on the modal characteristics and the natural frequency of the shaft system. The research in this paper contributes an evaluation of the dynamic characteristics of the runner of a hydraulic turbine unit, which is of great significance for the optimization of the analysis algorithm of the runner structure for large pumped storage units. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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18 pages, 18697 KiB  
Article
A Numerical Study of the Hydrodynamic Noise of Podded Propulsors Based on Proper Orthogonal Decomposition
by Changsheng Chen, Guoping Li, Zhenlai Ma, Ziyi Mei, Bo Gao and Ning Zhang
J. Mar. Sci. Eng. 2023, 11(11), 2054; https://doi.org/10.3390/jmse11112054 - 27 Oct 2023
Viewed by 649
Abstract
Podded propulsors have become a focal point of research in the field of marine propulsion in recent years due to their high efficiency, low noise, and excellent maneuverability. To investigate the acoustic characteristics induced by the flow field of podded propulsors, a high-precision [...] Read more.
Podded propulsors have become a focal point of research in the field of marine propulsion in recent years due to their high efficiency, low noise, and excellent maneuverability. To investigate the acoustic characteristics induced by the flow field of podded propulsors, a high-precision unsteady numerical simulation was conducted using the Delayed Detached Eddy Simulation (DDES) coupled with Ffowcs Williams–Hawkings (FW-H) equations. Multiple spatial acoustic receiving arrays were employed, and analysis methods including Proper Orthogonal Decomposition (POD) and Fast Fourier Transform (FFT) were utilized to determine the spatial distribution of the acoustic field of the podded propulsor. The results show that the blade passing frequency and the shaft frequency consistently dominate as the primary characteristic frequencies. On the plane of the propeller disk, the distribution of sound pressure levels is uniform without distinct directivity. Across the space curved surface, approximately the first ten POD modes encompass 99.8% of the total energy, and their spatial distribution characteristics of sound pressure are closely related to the pod structure. Additionally, these modes exhibit characteristic frequencies such as the blade passing frequency and shaft frequency. The spatial distribution of sound pressure at a single frequency on the spatial surface corresponds well with the results obtained from the POD analysis. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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18 pages, 12743 KiB  
Article
Analysis of Flow and Runner Dynamic Response Characteristics under Pump Conditions of Variable-Speed Pump Turbine
by Linmin Shang, Jingwei Cao, Lei Wang, Shuang Yu, Sen Ding, Zichao Wei, Zhengwei Wang and Xiaobing Liu
J. Mar. Sci. Eng. 2023, 11(8), 1493; https://doi.org/10.3390/jmse11081493 - 26 Jul 2023
Cited by 1 | Viewed by 971
Abstract
Pumped storage power stations can ensure the safe operation of the grid, as well as utilize clean energy sources to establish a low-carbon, safe, and efficient energy system. As pump turbines, the core components of pumped storage power plants, become more and more [...] Read more.
Pumped storage power stations can ensure the safe operation of the grid, as well as utilize clean energy sources to establish a low-carbon, safe, and efficient energy system. As pump turbines, the core components of pumped storage power plants, become more and more popular, the technical requirements for hydraulic design begin to improve year by year. However, when the unit operates far beyond the optimal range, the variable-speed pump turbine can overcome the shortcomings of the fixed-speed unit and solve the problem of unstable operation under partial load. The pressure pulsation of the unit in the pump condition is investigated by numerical simulation, analyzing the hydraulic thrust, and studying the dynamic response characteristics of the runner at a maximum speed of 456.5 rpm. Comparing the pressure pulsation amplitude of various components in the entire flow passage, the highest values of pressure pulsation were found in the runner and vaneless space. The axial hydraulic thrust has a fluctuation range between 174t and 198t and 0t to 40t for radial force. As per the structural analysis, it has been observed that the runner demonstrates uneven patterns in both its axial and radial deformations, with deformation mainly concentrated in radial displacement and stress distribution mainly concentrated on the blades near the crown. The dynamic stress amplitude of the runner at monitoring point S1 (located on the runner blade near the crown) is 37 MPa. This stress has a dominant frequency of 4.8fn, while the monitoring point S2 (located on the runner blade near the band) is 4 MPa, and the dominant frequency is 1.8fn. Using these findings, the design of the variable-speed pump turbine’s runner can be optimized, and the unit’s stable and secure operation can be guided accordingly. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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16 pages, 10012 KiB  
Article
An Impeller Optimization Method for the High Specific Speed Mixed-Flow Reactor Coolant Pump Applied to Marine Nuclear Power
by Qiang Fu, Yun Zhao, Yonggang Lu, Weiqiang Zhao and Rongsheng Zhu
J. Mar. Sci. Eng. 2023, 11(7), 1301; https://doi.org/10.3390/jmse11071301 - 26 Jun 2023
Viewed by 1011
Abstract
The reactor coolant pump (RCP) is the only rotating equipment in the primary circuit system of a nuclear power plant and the “heart” of the nuclear reactor. The L formula is defined, and the L/himp is introduced to study the influence of [...] Read more.
The reactor coolant pump (RCP) is the only rotating equipment in the primary circuit system of a nuclear power plant and the “heart” of the nuclear reactor. The L formula is defined, and the L/himp is introduced to study the influence of impeller blade type on the performance of the RCP. Twenty groups of models are designed, the concept of arc height ratio is proposed from the perspective of himp and L, and the distribution of internal entropy production within the impeller of the RCP under different Ls and himps of the impeller blade type is analyzed. The results show that when himp remains un-changed and L increases, the low-pressure area at the inlet of the impeller expands while the high-pressure area at the outlet decreases under the design flow or large flow conditions. The smoother blade profile reduces the occurrence of secondary flow phenomena and makes the RCP pressure distribution more uniform. Under design flow and large flow conditions, smaller L/himp and higher himp lead to higher efficiency and head performance. However, higher efficiency and lower head performance can be achieved under small flow conditions with larger L/himp and lower himp. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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16 pages, 7302 KiB  
Article
Influence of Guide Vane Opening on the Runaway Stability of a Pump-Turbine Used for Hydropower and Ocean Power
by Di Zhu, Wei Yan, Weilong Guang, Zhengwei Wang and Ran Tao
J. Mar. Sci. Eng. 2023, 11(6), 1218; https://doi.org/10.3390/jmse11061218 - 13 Jun 2023
Cited by 3 | Viewed by 1133
Abstract
Runaway is a common phenomenon in pump-turbines for hydropower and ocean power, accompanied by strong instability, which can easily lead to accidents. This study reveals the stability during the runaway process of a pump-turbine, mainly exploring the phenomenon of guide vane rejection happening [...] Read more.
Runaway is a common phenomenon in pump-turbines for hydropower and ocean power, accompanied by strong instability, which can easily lead to accidents. This study reveals the stability during the runaway process of a pump-turbine, mainly exploring the phenomenon of guide vane rejection happening in transition conditions when dealing with hydropower or ocean power. Through model experiments and computational fluid dynamics numerical simulations, the pressure pulsation when reaching runaway was compared under different guide vane opening angles. The amplitude of pressure pulsation measured in the experiment increases with the increase in guide vane opening, but there are also local changes in size and peak. The simulation results show that when the guide vane opening angle is 12 degrees, the vortex flow in the area between the guide vane and the runner of the unit increases, leading to instability. When the opening angle of the guide vane is between 12 and 20 degrees, the vortex flow intensity does not change much and the distribution becomes uniform, resulting in a decrease in the amplitude of pressure fluctuations. The pulsation of the flow field causes a dissipation of flow energy. Relationships can be found among velocity field, vortex intensity, and entropy production. This study is of great significance for ensuring the stable operation of pump-turbines. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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19 pages, 10349 KiB  
Article
Exploring the Mechanism of Strong-Pressure Fluctuation under Partial Load in the Turbine Mode of Pump Turbines for Hydro and Marine Power Storage
by Jiahao Lu, Wei Yan, Ran Tao, Zhengwei Wang and Di Zhu
J. Mar. Sci. Eng. 2023, 11(5), 1089; https://doi.org/10.3390/jmse11051089 - 22 May 2023
Viewed by 1054
Abstract
As a core component of pumped storage power plants for hydro and marine power storage, this paper investigates the mechanism of pressure pulsation fluctuations under different load conditions to improve the efficiency and operational stability of the storage units. The results of a [...] Read more.
As a core component of pumped storage power plants for hydro and marine power storage, this paper investigates the mechanism of pressure pulsation fluctuations under different load conditions to improve the efficiency and operational stability of the storage units. The results of a combination of experiments and numerical simulations showed that the pressure pulsation fluctuations in the pump turbine under strong and weak loads were significantly different at different monitoring points. The three-dimensional flow lines diagram of the pump turbine unit from the CFD numerical simulation showed that the flow line of the pump turbine was relatively chaotic and the vortex existed under weak load conditions. Pressure clouds and flow lines in the cross-section and longitudinal section of the pump turbine are shown. Both showed high-pressure values and a chaotic flow line with a vortex under weak load conditions. To a certain extent, it revealed the pressure pulsation fluctuation mechanism of the pump turbine and provides some guidance for solving practical problems in engineering. Full article
(This article belongs to the Special Issue Advancement in the Multiphase Flow in Fluid Machinery)
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