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Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic...
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Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: 25 August 2024 | Viewed by 37725

Special Issue Editors

Dr. Lijian Shi

E-Mail Website
Guest Editor
School of Hydraulic Science and Engineering, Yangzhou University (YZU), Yangzhou 225000, China
Interests: multidiscipline and multicondition optimization design of pumps; pump station transition process; pumping station design; computational fluid dynamics (CFD); flow measurements and experimental techniques
Special Issues, Collections and Topics in MDPI journals
Dr. Kan Kan

E-Mail Website
Guest Editor
College of Energy and Electrical Engineering, Hohai University, Nanjing, China
Interests: optimization of hydraulic machinery; numerical calculation method of hydraulic machinery; hydraulic transients in pump systems
Dr. Fan Yang

E-Mail Website
Guest Editor
College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou 225000, China
Interests: fluid machinery; pump device; design and optimization; computational fluid dynamics; flow stability
Prof. Dr. Fangping Tang

E-Mail Website
Guest Editor
College of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225000, China
Interests: fluid machinery; axial-flow pump; hydraulic transient simulation; pump station
Dr. Wenjie Wang

E-Mail Website
Guest Editor
National Research Center of Pumps, Jiangsu University, Zhenjiang 212013, China
Interests: pumps; design and optimization; transient processes; pressure fluctuation; pump system
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Flow instability is one of the most important research topics in the field of hydraulic machinery. Advanced numerical simulation and experiment methods are important means to study the unstable flow characteristics of hydraulic machinery. Recently, there has been a number of works showing the flow instability characteristics of hydraulic machinery based on advanced numerical simulation and experimentation methods. These unstable flows are mainly characterized by performance changes, pressure pulsations, secondary reflux, etc. The unstable flow may cause undesirable phenomena such as pulsation, unit vibration, severe performance degradation, etc. Advanced numerical simulation methods and experimentation methods allow us to learn more about the unstable flow mechanism inside hydraulic machinery.

This Special Issue on “Advanced Simulation and Experimentation Methods of Flow Instability in Hydraulic Machinery” seeks high-quality works focusing on the latest simulation and experiment technology for hydraulic machinery. Topics include but are not limited to:

  • Flow instability phenomena in hydraulic machinery;
  • Advanced simulation and experimentation methods of hydraulic machinery;
  • Optimization design of pump;
  • Research on the transition process of hydraulic machinery;

Internal flow mechanism of hydraulic machinery.

Dr. Lijian Shi
Dr. Kan Kan
Dr. Fan Yang
Prof. Dr. Fangping Tang
Dr. Wenjie Wang
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. Processes 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 2400 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

  • hydraulic machinery
  • flow instability
  • CFD
  • experiment

Published Papers (28 papers)

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37 pages, 33787 KiB  
Article
Pulsation Stability Analysis of a Prototype Pump-Turbine during Pump Mode Startup: Field Test Observations and Insights
by Ming Xia, Weiqiang Zhao, Zhengwei Wang and Mu Qiao
Processes 2024, 12(4), 838; https://doi.org/10.3390/pr12040838 - 21 Apr 2024
Viewed by 195
Abstract
Pump-turbines experience complex flow phenomena and fluid–structure interactions during transient operations, which can significantly impact their stability and performance. This paper presents a comprehensive field test study of the pump mode startup process for a 150 MW prototype pump-turbine. By analyzing pressure fluctuations, [...] Read more.
Pump-turbines experience complex flow phenomena and fluid–structure interactions during transient operations, which can significantly impact their stability and performance. This paper presents a comprehensive field test study of the pump mode startup process for a 150 MW prototype pump-turbine. By analyzing pressure fluctuations, structural vibrations, and their short-time Fourier transform (STFT) results, multiple stages were identified, each exhibiting distinct characteristics. These characteristics were influenced by factors such as runner rotation, free surface sloshing in the draft tube, and rotor–stator interactions. The natural frequencies of the metallic components varied during the speed-up and water-filling stages, potentially due to gyroscopic effects or stress-stiffening phenomena. The opening of the guide vanes and dewatering valve inside the guide vanes significantly altered the amplitude of the rotor–stator interaction frequency, transitioning the vibration behavior from forced to self-excited regimes. Interestingly, the draft tube pressure fluctuations exhibited sloshing frequencies that deviated from existing prediction methods. The substantial phenomena observed in this study can help researchers in the field to deepen the understanding of the complex behavior of pump-turbines during transient operations and identify more meaningful research directions. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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21 pages, 10362 KiB  
Article
Influence of Partition Wall Length on Inlet Flow Regime of a Pumping Station Arranged in Parallel with a Sluice Gate
by Wei Shi, Fusheng Lv, Xianlei Yu, Xichen Wang, Chun Ni, Weigang Lu and Lei Xu
Processes 2024, 12(4), 699; https://doi.org/10.3390/pr12040699 - 29 Mar 2024
Viewed by 326
Abstract
When a sluice gate is arranged in parallel with pumping station units, biased flow occurs in the forebay when the units are operating. The transverse flow velocity in front of the channel inlet is relatively high, and, in severe cases, it may lead [...] Read more.
When a sluice gate is arranged in parallel with pumping station units, biased flow occurs in the forebay when the units are operating. The transverse flow velocity in front of the channel inlet is relatively high, and, in severe cases, it may lead to the formation of suction vortices, impacting the stable operation of pump units. Taking the Liushan Pumping Station project of the Eastern Route of the South-to-North Water Diversion Project as a case study, this paper investigates the effect of the partition wall length on the inlet flow regime of pumping station units arranged in parallel with the sluice gate to reduce the transverse flow velocity in front of the channel inlet. Using numerical simulations, the inlet flow regimes for different partition wall lengths were compared. Moreover, the flow field distributions in the forebay under different operating conditions were analyzed alongside the transverse flow velocity in front of the channel inlet and the uniformity of flow velocity distribution in the section behind the channel inlet. Hydraulic model tests were then conducted to validate the simulation results. The results indicate that in the original design, there existed a vortex zone in the forebay in front of the inlet of the channel where the transverse flow was relatively high. However, the introduction of partition walls significantly reduced the transverse flow velocity in front of the inlet of the channel in the forebay. The optimal effect was achieved when the length of the partition wall was twice the width of the inlet channel. Furthermore, the uniformity of velocity distribution at the inlet of the channel increased by an average of 7.4%, leading to a substantial improvement in the inlet flow regime of the pumping station. The addition of partition walls in the forebay effectively resolved the issues related to the flow regime in the forebay, providing valuable references for similar engineering studies in the future. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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24 pages, 8714 KiB  
Article
Study of the Optimization of Rail Pressure Characteristics in the High-Pressure Common Rail Injection System for Diesel Engines Based on the Response Surface Methodology
by Ruichuan Li, Wentao Yuan, Jikang Xu, Lin Wang, Feng Chi, Yong Wang, Shuqiang Liu, Jianghai Lin, Qingguang Zhang and Lanzheng Chen
Processes 2023, 11(9), 2626; https://doi.org/10.3390/pr11092626 - 03 Sep 2023
Cited by 1 | Viewed by 1048
Abstract
This paper establishes a mathematical model of the high-pressure common rail injection system used in diesel engines according to the parameters of its key components, and AMESim 2020 software was used to establish a simulation model of the common rail injection system used [...] Read more.
This paper establishes a mathematical model of the high-pressure common rail injection system used in diesel engines according to the parameters of its key components, and AMESim 2020 software was used to establish a simulation model of the common rail injection system used in diesel engines. The simulation model mainly includes a high-pressure oil pump model, a common rail pipe model, and a model of four injectors. This paper also describes an experimental analysis of the accuracy of the established simulation model. Through a simulation analysis of the system rail’s pressure fluctuation and pressure characteristics, it was concluded that the length of the common rail pipe, the diameter of the common rail pipe, and the inner diameter of the high-pressure fuel pipes are important influencing parameters for the rail pressure characteristics of the system. In this study, according to the original common rail pipe and high-pressure fuel pipe model, a response surface methodology was used to optimize and analyze the parameters of the common rail pipe and high-pressure fuel pipes, and the optimal size parameters for the common rail pipe and high-pressure fuel pipes were obtained with the minimum rail pressure fluctuations and the average rail pressure setpoint. After the optimization, the pressure for the common rail pipe of the high-pressure common rail system was increased by 0.82%, the pressure fluctuation was reduced by 21.66%, the injection pressure was increased by 1.15%, the single injection volume was increased by 0.86%, and its fuel injection characteristics were significantly improved. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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14 pages, 9658 KiB  
Article
Simulation Analysis of the Effect of Slit/Slot Pintle Geometry on Atomization of Bipropellant Engine
by Kun Cai, Zhen Zhang, Fengshan Wang, Yu Hu, Xudong Wang, Zhicheng Fang, Xiaofang Mao, Zhaopu Yao, Yusong Yu and Haiwang Li
Processes 2023, 11(8), 2471; https://doi.org/10.3390/pr11082471 - 17 Aug 2023
Viewed by 981
Abstract
In order to optimize the slit/slot geometry design of a bipropellant pintle injector, the impinging spray development of a pintle injector was numerically investigated. The VOF (volume of fluid) and LES (large eddy simulation) methods were employed for an analysis to capture the [...] Read more.
In order to optimize the slit/slot geometry design of a bipropellant pintle injector, the impinging spray development of a pintle injector was numerically investigated. The VOF (volume of fluid) and LES (large eddy simulation) methods were employed for an analysis to capture the gas–liquid interface by means of the AMR (adaptive mesh refinement) method. In those simulation cases, different flowrates, slot numbers, pintle diameters, slot thicknesses and slot shapes were compared for an analysis. In a comparison of visualization and quantification, a high flowrate and large pintle diameter were shown to be more positive features for improving the atomization quality and mixing effect. As for the slot parameters and shape, the spray development was mainly determined by the flow proportion between the slit jet and slot jet. The simulation results indicated that dominant slot jets cause a more dispersed spatial distribution, which is more conducive to the subsequent improvement of combustion efficiency in a limited space. However, an excessive increase in the number of slot jets can weaken the overall atomization quality and mixing effect, so it is suggested to ensure a balance for geometry design optimization. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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20 pages, 6918 KiB  
Article
Throttling Loss Energy-Regeneration System Based on Pressure Difference Pump Control for Electric Forklifts
by Yuanzheng Lin, Tianliang Lin, Zhihong Li, Haoling Ren, Qihuai Chen and Junyi Chen
Processes 2023, 11(8), 2459; https://doi.org/10.3390/pr11082459 - 16 Aug 2023
Cited by 1 | Viewed by 890
Abstract
At present, the hydraulic systems of electric forklifts and traditional internal combustion forklifts are mostly valve-controlled speed-regulation systems, which have large throttling losses and potential energy waste. To further improve the energy-saving ability of electric forklifts, the forklift’s common working conditions are analyzed [...] Read more.
At present, the hydraulic systems of electric forklifts and traditional internal combustion forklifts are mostly valve-controlled speed-regulation systems, which have large throttling losses and potential energy waste. To further improve the energy-saving ability of electric forklifts, the forklift’s common working conditions are analyzed in this paper. A throttling loss energy-regeneration system based on pressure difference pump control is designed, and the system’s working principle is described. Aiming to deal with the problem that the pump−valve compound speed regulation with constant pressure difference could not realize high controllability and energy saving at the same time, a control strategy for variable pressure difference pump−valve compound speed regulation based on pressure balance control is proposed. The handle signal is positively related to the target speed of the oil cylinder. In the low-speed stage, the closed-loop control of the actual output torque of the motor/generator keeps the pressure difference across the proportional throttle valve unchanged, and the speed adjustment is realized by changing the opening of the proportional throttle valve. In the high-speed stage, the valve opening area is kept unchanged and the target pressure difference is changed to achieve the target speed. Finally, the feasibility of the control strategy is verified through an AMESim simulation, and the minimum pressure difference switching point is determined through experiments. The experiments show that the system’s energy-saving efficiency can reach 21.5% under a 1 t load. With the increase in the load, the system’s energy-saving efficiency can be further improved. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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15 pages, 7731 KiB  
Article
Analysis of Vortex Evolution in the Runner Area of Water Pump Turbine under Runaway Conditions
by Feng Zhou, Qifei Li and Lu Xin
Processes 2023, 11(7), 2080; https://doi.org/10.3390/pr11072080 - 12 Jul 2023
Cited by 1 | Viewed by 671
Abstract
In order to study the evolution principle of the coherent structure in the low flow rate runaway condition, the pump turbine of a certain pumped storage power plant was employed. The transient dynamic stress of the runner was numerically simulated and examined in [...] Read more.
In order to study the evolution principle of the coherent structure in the low flow rate runaway condition, the pump turbine of a certain pumped storage power plant was employed. The transient dynamic stress of the runner was numerically simulated and examined in this study in order to analyze the coherent structure of the vortex and the stability of the grid connection during the transition process. Based on the realizable k-ε turbulent model, the unsteady flow of the whole pump turbine channels was calculated. The results show that the flow in the runner channels presents with a turbulence state, and with many different scales vortices. These vortex structures are mainly distributed in the inlet region of the blade, the area of the blade trailing edge and the middle section of the runner channels. These vortex structures affect the distribution of the blade pressure load. Moreover, the vortex structure at the inlet of the runner depends on the change in the attack angle. In the flow region formed at the outlet of the blade near the suction surface and the runner cone, the blade has a limited effect on the fluid; thus, the vortex structure depends on the Coriolis force and the centrifugal force joint action. The evolution of these vortex structures will have a greater impact on the grid connection of the power station. During the operation of the power station, it is necessary to reduce the time of transitional conditions so that the power station can operate efficiently. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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17 pages, 5946 KiB  
Article
A New Fast Calculating Method for Meshing Stiffness of Faulty Gears Based on Loaded Tooth Contact Analysis
by Zhe Liu, Haiwei Wang, Fengxia Lu, Cheng Wang, Jiachi Zhang and Mingjian Qin
Processes 2023, 11(7), 2003; https://doi.org/10.3390/pr11072003 - 03 Jul 2023
Viewed by 1001
Abstract
Gear transmission systems are widely used in various fields. The occurrence of gear cracks, tooth pitting, and other faults will lead to the dynamic characteristics deterioration of the transmission system. In order to calculate the meshing stiffness of faulty gear pairs more effectively [...] Read more.
Gear transmission systems are widely used in various fields. The occurrence of gear cracks, tooth pitting, and other faults will lead to the dynamic characteristics deterioration of the transmission system. In order to calculate the meshing stiffness of faulty gear pairs more effectively and precisely, this article improves the loaded tooth contact analysis (LTCA) method by analyzing the influence of different fault types on gear deformation, including bending-shearing deformation and contact deformation, which combines the accuracy of the finite element method (FEM) and the rapidity of the analytical method (AM). The improved LTCA method can model the fault areas accurately and optimize the deformation coordination equation under the actual meshing situation of the faulty gear tooth, making it suitable for calculating the meshing stiffness of faulty gears. Based on the calculation results of the finite element method, the accuracy of the improved meshing stiffness calculation method has been verified, and the sensitivity of different fault type parameters on meshing stiffness has been studied. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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20 pages, 9113 KiB  
Article
Research on the Strength Calculation Method and Effects of Gear Parameters for High-Coincidence High-Tooth Gears
by Jiachi Zhang, Haiwei Wang, Yi Liu, Shengwen Hou, Zhe Liu and Huan Wang
Processes 2023, 11(6), 1807; https://doi.org/10.3390/pr11061807 - 14 Jun 2023
Viewed by 1401
Abstract
This article studies the calculation method for the tooth root bending stress of a high-tooth gear pair with a high contact ratio. The boundary point of the double-tooth meshing zone of the high-tooth gear pair is used as the loading point for the [...] Read more.
This article studies the calculation method for the tooth root bending stress of a high-tooth gear pair with a high contact ratio. The boundary point of the double-tooth meshing zone of the high-tooth gear pair is used as the loading point for the load, and the calculation formula for the bending stress at the dangerous section of the tooth root is obtained. By using ANSYS finite element simulation, the effect of the addendum coefficient, pressure angle, and other gear parameters on the bending stress of the tooth root is studied. The analysis shows that increasing the pressure angle will reduce the bending strength of the tooth root. Increasing the coefficient of a tooth’s top height will lead to an increase in the bending strength of the tooth root. Comparing the finite element analysis (FEA) results with the theoretical calculation results, the analysis shows that under low loads, the maximum error of the theoretical calculation values of the driving toothed gear and driven gear shall not exceed 13.53% and 15.42%, respectively. Under high loads, the maximum theoretical errors of the driving toothed gear and driven gear shall not exceed 8.78% and 10.91%, respectively. This verifies the correctness of the calculation method, which is of great significance for improving the load-bearing capacity of high-tooth gears and for guiding tooth shape design. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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12 pages, 24101 KiB  
Article
Study on the Dynamic Characteristics of the Impact Loads in a Near-Wall Double-Cavitation Bubble Collapse
by Wei Han, Zitian Xu, Yingjian Hao, Jiale Ren, Wangxu Li and Zhenye Gu
Processes 2023, 11(6), 1805; https://doi.org/10.3390/pr11061805 - 14 Jun 2023
Viewed by 910
Abstract
Cavitation and cavitation erosion are complex hydrodynamic behaviors that significantly influence the stability and reliability of pumping units in aerospace and navigation power systems, hydraulic engineering, and other fields. Studies on cavitation have primarily and heavily focused on the collapse of multiple cavitation [...] Read more.
Cavitation and cavitation erosion are complex hydrodynamic behaviors that significantly influence the stability and reliability of pumping units in aerospace and navigation power systems, hydraulic engineering, and other fields. Studies on cavitation have primarily and heavily focused on the collapse of multiple cavitation bubbles; understanding the movement of multiple cavitation bubbles is important for cavitation research. In this study, the collapse process of near-wall double-cavitation bubbles was numerically simulated and experimentally verified, and the evolution of the near-wall double-cavitation bubble collapse was investigated. Two different distances were altered in the study. The distance between the double-cavitation bubble and the distance between the cavitation bubbles and the wall, the effects of dimensionless parameters, such as the near-wall coefficient and the cavitation bubble spacing coefficient, the collapse time, jet angle, and impact load on the wall can be determined. It was found that the collapse time of the double-cavitation bubbles decreased in a negative exponential distribution with an increase in the cavitation bubble spacing coefficient, along with decreases in a negative exponential distribution with an increase in the near-wall coefficient. The jet angle increased in a negative exponential distribution with an increase in the cavitation bubble spacing coefficient and decreased in a negative exponential distribution with an increase in the near-wall coefficient. The impact load on the wall initially increased and then decreased in the form of a quadratic function, with an increase observed in the cavitation bubble spacing coefficient. With an increase in the near-wall coefficient, the impact load on the wall first decreased, then increased, and finally decreased in the form of a cubic function. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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18 pages, 5460 KiB  
Article
Comparative Analysis of the Hydrodynamic Performance of Arc and Linear Flapping Hydrofoils
by Ertian Hua, Wenchao Zhu, Rongsheng Xie, Zhongxin Su, Haitao Luo and Linfeng Qiu
Processes 2023, 11(5), 1579; https://doi.org/10.3390/pr11051579 - 22 May 2023
Cited by 2 | Viewed by 1019
Abstract
In order to improve the hydrodynamic performance of flapping hydrofoils and solve the problem of insufficient hydrodynamic force in plain river network areas, in this study, we consider the more realistic swing of fish tails and propose an arc flapping method, the coupled [...] Read more.
In order to improve the hydrodynamic performance of flapping hydrofoils and solve the problem of insufficient hydrodynamic force in plain river network areas, in this study, we consider the more realistic swing of fish tails and propose an arc flapping method, the coupled motion of which has three degrees of freedom: heave, pitch, and lateral displacement. Two flapping methods, positive arcs and negative arcs, were derived on the basis of the lateral displacement direction. By using the finite volume method (FVM) and overlapping grid technology, a numerical simulation was conducted to compare and analyze the pumping performance of three types of flapping hydrofoil, namely, linear, positive arcs, and negative arcs, in order to further provide guidance for the structural optimization of bionic pumping devices. The results showed that the wake vortex structures of the three flapping modes all had anti-Kármán vortex streets, but the wake vortex of linear flapping deflected upward, and the wake vortex of positive arc flapping tended to be further away in the flow field. In one cycle, thrust was always generated by the positive arc flapping hydrofoil and the linear flapping hydrofoil, but the thrust coefficient curve of the positive arc flapping hydrofoil was more stable than that of the linear flapping hydrofoil, and the peak value was reduced by 46.5%. In addition, under the conditions of a flow rate of 750 L·s−1 and an average head of 0.006 m, the pumping efficiency of the positive arc flapping hydrofoil reached 35%, thus showing better pumping performance than the traditional linear flapping hydrofoil under conditions with ultra-low head. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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29 pages, 16193 KiB  
Article
Optimal Design of Perforated Diversion Wall Based on Comprehensive Evaluation Indicator and Response Surface Method: A Case Study
by Bo Xu, Shuaipeng Xu, Hui Xia, Jianfeng Liu, Yiyun Shen, Lei Xu, Wang Xi and Weigang Lu
Processes 2023, 11(5), 1539; https://doi.org/10.3390/pr11051539 - 17 May 2023
Viewed by 769
Abstract
To investigate the impact of parameters of diversion wall holes on the flow state in the forebay of a combined sluice-pumping station project and optimize the relevant parameters, a total of 50 numerical simulations based on the CFD technique were performed, adopting the [...] Read more.
To investigate the impact of parameters of diversion wall holes on the flow state in the forebay of a combined sluice-pumping station project and optimize the relevant parameters, a total of 50 numerical simulations based on the CFD technique were performed, adopting the design of orthogonal experiments with 25 schemes under self-draining conditions and pumping conditions, respectively. For synthesizing flow state evaluation indicators under self-draining and pumping conditions, the variation coefficient method was used, and the results were analyzed through the response surface method. Thus, the relationship between the parameters of the diversion wall holes and the comprehensive evaluation indicator was established. The steepest ascent method was used to obtain the optimal parameters, and the results showed that the optimized holes can balance the flow state under self-draining and pumping conditions in the combined sluice-pumping station project. Compared to the case with the diversion wall unperforated, the uniformity of axial velocity distribution in the 6# inlet channel and 7# sluice chamber increased by 6.6% and 5.2%, respectively, and the maximum transverse velocity decreased from 0.32 m/s to 0.21 m/s, with a fall of 34.4%. This study provides reference and technical support for the hydraulic characteristic analysis, optimization design and rectifying measures selection of the combined sluice-pumping station project. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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19 pages, 7018 KiB  
Article
Vibration Characteristics of Concrete Pump Trucks with Multiple Postures and Multiple Conditions Based on the Secondary Development of HyperWorks
by Yafeng Ren, Weifeng Yang, Xiaohui Sun, Jinning Zhi, Jie Li and Haiwei Wang
Processes 2023, 11(5), 1483; https://doi.org/10.3390/pr11051483 - 13 May 2023
Cited by 2 | Viewed by 1234
Abstract
Due to the excitation generated by the periodically alternate pumping of dual-hydraulic cylinders, vibration of concrete pump trucks (CPT) occurs. Excessive boom vibration will seriously affect the service life and operation safety of CPT. At the same time, the long boom structure of [...] Read more.
Due to the excitation generated by the periodically alternate pumping of dual-hydraulic cylinders, vibration of concrete pump trucks (CPT) occurs. Excessive boom vibration will seriously affect the service life and operation safety of CPT. At the same time, the long boom structure of a CPT makes it very sensitive to the posture and pumping conditions, which directly affect the vibration characteristics of CPT in different postures and different working conditions. This paper establishes a finite element model of a type of CPT. Through force analysis of concrete in the straight pipe and elbow pipe during the pumping and reversing stages, an excitation model of the conveying pipe is established. Based on the secondary development of HyperWorks, a finite element model of CPT with multiple postures is built, and the dynamic response under multiple conditions is analyzed. Finally, the accuracy of the finite element model of CPT and the excitation model of the conveying pipe is verified by experiment. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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20 pages, 8290 KiB  
Article
Study on Flow Characteristics of Hydraulic Suction of Seabed Ore Particles
by Qiu Xia, Hao Jia, Jiuchun Sun, Xiaoguang Xi and Jingyu Cui
Processes 2023, 11(5), 1376; https://doi.org/10.3390/pr11051376 - 02 May 2023
Viewed by 1313
Abstract
Efficient and environmentally friendly ore collecting operation requires that the ore collecting head can provide just enough suction to start the ore particles in different working conditions. In this work, computational fluid dynamics and discrete element method (CFD-DEM) is used to simulate the [...] Read more.
Efficient and environmentally friendly ore collecting operation requires that the ore collecting head can provide just enough suction to start the ore particles in different working conditions. In this work, computational fluid dynamics and discrete element method (CFD-DEM) is used to simulate the hydraulic suction process of ore particles. After analyzing the pressure and velocity characteristics of the flow field, the effects of different suction velocities on the lateral displacement offset, drag coefficient Cd and Reynolds number Rep of particles are studied. It is determined that the lifting force is caused by the different flow velocities of the upper and lower flow fields; particle start-up time and the lateral offset are inversely proportional to suction speed. When h/d ≥ 2.25, the vertical force on particles is no longer affected by h/d. When S/d = 2.5, FZ decreases to 0 N; when h/d increases from 1.5 to 1.75, FZ decreases by nearly half. Three empirical equations for FZ represented by D/d, h/d, and S/d are obtained. After integrating the above three equations, the functional relationship of FZ with D/d, h/d and S/d is finally obtained within a certain range. The errors of the equations are within 6%. The particle stress characteristics obtained in this paper can be applied to the establishment of ore collecting performance prediction model and provide data support for the research and development of intelligent ore collecting equipment. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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18 pages, 4600 KiB  
Article
Layering Vibration Transfer Path Analysis of a Flexible Supported Gear System Based on the Vibration Power Flow Theory
by Yafeng Ren, Xiaohui Sun, Yusheng Luo, Wenwen Lu and Haiwei Wang
Processes 2023, 11(4), 1233; https://doi.org/10.3390/pr11041233 - 16 Apr 2023
Cited by 1 | Viewed by 1335
Abstract
In the marine gear system, the vibration of gears is transmitted to the ship foundation through shafts, bearings, housing, and isolators, and then the underwater noise is generated. Analyzing the vibration transfer properties and identifying the critical path can provide guidance to the [...] Read more.
In the marine gear system, the vibration of gears is transmitted to the ship foundation through shafts, bearings, housing, and isolators, and then the underwater noise is generated. Analyzing the vibration transfer properties and identifying the critical path can provide guidance to the low-noise design of the gear system. In this paper, a coupled gear-housing-foundation dynamic model is proposed for a flexible supported gear system, in which the flexibility of each subsystem and the coupling relationship between them are taken into account. The transferring process of gear vibration is divided into different layers between gears, shafts, bearings, housing, isolators, and ship foundation. Based on the vibration power flow (VPF) theory, detailed layering vibration transfer path analyses of the gear isolation coupled system are carried out for both location path and direction path, and the main paths are identified in a broad speed range. The results indicate that though the gear vibration transferred to the foundation attenuate layer by layer, there may be reverse VPF in some special location path and direction path under resonance conditions. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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18 pages, 6988 KiB  
Article
Analysis of Inner Flow in a Multi-Stage Double-Suction Centrifugal Pump Using the Detached Eddy Simulation Method
by Wenjie Peng, Ji Pei, Shouqi Yuan, Jiabin Wang, Benying Zhang, Wenjie Wang and Jiaxing Lu
Processes 2023, 11(4), 1026; https://doi.org/10.3390/pr11041026 - 28 Mar 2023
Cited by 2 | Viewed by 1245
Abstract
In order to analyze the inner flow in a multi-stage double-suction centrifugal pump, which is regarded as a common way of knowing the current characteristics of the pump and as the basis of optimization for better performance, a numerical simulation considering the velocity [...] Read more.
In order to analyze the inner flow in a multi-stage double-suction centrifugal pump, which is regarded as a common way of knowing the current characteristics of the pump and as the basis of optimization for better performance, a numerical simulation considering the velocity field distribution characteristics and pressure fluctuation propagation law using the detached eddy simulation method was conducted. Additionally, the principle of entropy generation was put to use to quantify and compare the energy loss of different components. The results reveal that the existence of unstable flow structures in the first-stage impeller and a large number of vortical structures in the back-channel result in reduced operational efficiency of the pump. Furthermore, the pressure fluctuation intensity reaches its maximum with 0.15 at the blade trailing edge, which propagates to the tongue region of the forward flow channel and the double-volute under the low rates condition. Additionally, the main frequency of the monitoring points in the inter-stage flow channel and volute is basically located at a frequency of 198.667 Hz, which is twice the blade frequency. Consequently, the wall entropy production accounting for nearly 25% cannot be ignored and that the loss mainly occurs in the double-volute and the inter-stage flow channel due to the occurrence of irregular flow in the above components with more than 50%. The outcomes of this research present a valuable point of reference for the optimization of structural design in multistage turbomachines with various applications. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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10 pages, 1578 KiB  
Article
Liquid Loading of Horizontal Gas Wells in Changbei Gas Field
by Zhimin Huang, Wenbin Cai, Huiren Zhang and Xiangyang Mo
Processes 2023, 11(1), 134; https://doi.org/10.3390/pr11010134 - 02 Jan 2023
Cited by 2 | Viewed by 1951
Abstract
The Changbei gas field, which initially exhibited high gas-production performance, is dominated by large-displacement horizontal wells. With the decrease in reservoir pressure, the liquid loading in the gas well is currently severe, and production has been rapidly decreasing. Thus, recognizing the gas-well liquid [...] Read more.
The Changbei gas field, which initially exhibited high gas-production performance, is dominated by large-displacement horizontal wells. With the decrease in reservoir pressure, the liquid loading in the gas well is currently severe, and production has been rapidly decreasing. Thus, recognizing the gas-well liquid loading to maintain stable gas-well production is necessary. A method was established to identify the water source of the liquid loading in the Changbei gas field. First, formation water and condensate water were identified based on the mineralization of the recovered water and the mass concentration of Cl− and K+ + Na+, and then the condensate content of the water produced in the gas well was qualitatively evaluated. The water–gas ratio curve for the gas well was plotted to determine whether the produced water was edge-bottom water, pore water, or condensate. Then a method was established to distinguish the start time of liquid loading in the gas well using a curve depicting a decrease in production; the method was also used to estimate the depth of the gas well where liquid loading occurs, according to the bottomhole pressure. First, based on the available production data, the Arps decline model was applied to fit the production curve for the entire production phase; the resulting curve was compared with the actual production curve of the gas well, and the two curves diverged when fluid accumulation began in the gas well. Finally, the liquid-loading depth of the gas well was estimated based on the bottomhole pressure. This method can be used to determine the fluid accumulation and calculate the liquid-loading depth of gas wells with unconnected oil jackets. The analysis revealed that in the Changbei gas field, condensate was the type of water primarily produced in 35 gas wells, accounting for 62.5% of the total number of gas wells. Edge-bottom water was the type of water primarily produced in 16 gas wells, accounting for 28.6% of the total number of gas wells. In the remainder of the gas wells, pore water was the water primarily produced; the calculations of accumulation time and accumulation volume of typical gas wells in the block revealed that some gas wells started to accumulate liquid after 45–50 months, and the amount of accumulation could reach several tens of meters, while others were in good production condition. The method established in this paper could enhance our understanding of liquid loading in gas wells in the Changbei gas field and lay a foundation for the development of gas-well deliquification techniques. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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20 pages, 8671 KiB  
Article
Analysis of the Flow Field at the Tip of an Axial Flow Compressor during Rotating Stall Process Based on the POD Method
by Yueheng Wang, Moru Song, Jiali Xin and Bo Yang
Processes 2023, 11(1), 69; https://doi.org/10.3390/pr11010069 - 27 Dec 2022
Cited by 2 | Viewed by 2182
Abstract
Rotating stalls are one of the most dangerous phenomena to be avoided in the designing and operating of axial flow compressors. An understanding of the evolution of the flow characteristics around the rotor tip region is important to study the process of stall [...] Read more.
Rotating stalls are one of the most dangerous phenomena to be avoided in the designing and operating of axial flow compressors. An understanding of the evolution of the flow characteristics around the rotor tip region is important to study the process of stall development. In this paper, some critical characteristics of the stall-related structures, which could not be observed by the traditional analysis methods, are understood by using the proper orthogonal decomposition (POD) method. The detailed unsteady flow fields in a typical transonic axial flow compressor during the stall process are obtained by the validated numerical simulation. Thereafter, the proper orthogonal decomposition method, as a method for model reduction and decomposition, is adopted to extract the flow characteristics from the numerical results of the stall process. It is found that the flow characteristics during the stall process can be well decomposed by the POD method. The pre-stall POD results show that the important flow features can be extracted and revealed in the low-order modes, which are not obvious in the original flow field. When the stall cells are formed and developed, the flow characteristics are gradually determined by the modes, which are related to the features of the stall cells. When the compressor is operated under stable stall conditions, the low-order POD modes are composed of a series of harmonic modes, which are sinusoid-like in space and time with the frequency of the stall cell rotation. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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11 pages, 2597 KiB  
Article
Velocity String Drainage Technology for Horizontal Gas Wells in Changbei
by Wenbin Cai, Zhimin Huang, Xiangyang Mo and Huiren Zhang
Processes 2022, 10(12), 2640; https://doi.org/10.3390/pr10122640 - 08 Dec 2022
Cited by 2 | Viewed by 1798
Abstract
The Changbei gas field is dominated by wells with large horizontal displacement, which have exhibited high gas production performance at an early stage of development. With the decrease in reservoir pressure, the liquid loading in the gas well is relatively high and gas [...] Read more.
The Changbei gas field is dominated by wells with large horizontal displacement, which have exhibited high gas production performance at an early stage of development. With the decrease in reservoir pressure, the liquid loading in the gas well is relatively high and gas production rapidly decreases. Therefore, suitable drainage measures are required to maintain stable gas production. Based on the characteristics of the unconnected oil jacket of gas wells in Changbei, a velocity string was used for drainage. A critical liquid-carrying model was established to determine the location of liquid loading in horizontal gas wells in Changbei. First, the coefficients of the liquid-carrying model were determined through theoretical analysis of the characteristics of the gas well formation. Then, the depth setting of the velocity string was analyzed. The critical liquid-carrying model was employed to calculate the liquid-carrying flow rate of each section; the calculated flow rates were compared with the actual flow rates to determine whether fluid accumulation occurred in each section of the gas well. Thereafter, with the help of the oil and casing position, the suitable setting position of the velocity string was determined. The formation fluid was driven from the tubing into the casing owing to the increase in the overflow area, based on the principle of reducer fluid mechanics. The fluid velocity in the larger overflow cross-section decreased, thereby reducing the drainage capacity of the gas well and resulting in liquid loading. Finally, a timing analysis was performed. After the formation pressure decreased, the well production and flow rate changes were analyzed by placing two velocity strings of different sizes at different wellhead pressures in the gas well with fluid accumulation. The results indicated that although the velocity string was set at a position suitable for fluid drainage, fluid accumulation still occurred after a production period, thus necessitating replacement deliquification. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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17 pages, 6736 KiB  
Article
Investigation on the Influence of Flow Passage Structure on the Performance of Bionic Pumps
by Ertian Hua, Haitao Luo, Rongsheng Xie, Wanqian Chen, Shouwei Tang and Dongyang Jin
Processes 2022, 10(12), 2569; https://doi.org/10.3390/pr10122569 - 02 Dec 2022
Cited by 3 | Viewed by 1185
Abstract
The flapping hydrofoil bionic pump drives the hydrofoil to make simple harmonic motion and completes one-way water pumping in the flow passage. As a new pump device that can realize ultra-low head water delivery, the flapping hydrofoil device can effectively enrich the drainage [...] Read more.
The flapping hydrofoil bionic pump drives the hydrofoil to make simple harmonic motion and completes one-way water pumping in the flow passage. As a new pump device that can realize ultra-low head water delivery, the flapping hydrofoil device can effectively enrich the drainage methods of plain rivers and improve water delivery efficiency, and the passage structure is the key factor of ultra-low head devices. In this paper, the two-dimensional flow passage models are established, and the flapping of the airfoil is realized by using the dynamic grid technology. Based on the continuity equation, k-ε turbulence model, and Reynolds time-averaged equation, the flapping hydrofoil device is simulated by transient calculation. The hydraulic performance characteristics of various passages with different widths, such as square passages, micro-arc passages, and convergent–divergent passages, are calculated and simulated. The results show that, under the fixed motion parameters, the narrower the passage width, the higher the outlet velocity, lift, and efficiency of the device, the lower the flow rate. The contraction–expansion pipe can effectively improve the efficiency and flow rate of the device, and, before the wake is stable, the longer the contraction section the better the lifting effect. However, the micro-arc pipeline will affect the formation of a double-row anti-Karman vortex street, resulting in greater energy loss and in its hydraulic performance being inferior to that of the square passage. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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24 pages, 19356 KiB  
Article
Flow Characteristics and Anti-Vortex in a Pump Station with Laterally Asymmetric Inflow
by Can Luo, Yufan He, Yinan Shang, Xiao Cong, Chao Ding, Li Cheng and Shuaihao Lei
Processes 2022, 10(11), 2398; https://doi.org/10.3390/pr10112398 - 14 Nov 2022
Cited by 3 | Viewed by 1400
Abstract
In a laterally asymmetric intake pumping station, the flow direction in the forebay is not consistent with flow in the intake channel. Thus, the adverse flow patterns, such as bias flow, large-scale vortex and asymmetric flow occur frequently in the forebay and sump. [...] Read more.
In a laterally asymmetric intake pumping station, the flow direction in the forebay is not consistent with flow in the intake channel. Thus, the adverse flow patterns, such as bias flow, large-scale vortex and asymmetric flow occur frequently in the forebay and sump. Based on the Reynolds-averaged Navier-Stokes (RANS) equation and the RNG k-ε turbulence model, a recent flow pattern in a laterally asymmetric intake pumping station was numerically simulated and analyzed, and effective vortex elimination measures were proposed. For the original scheme, seriously biased flow combined with large-scale vortices were observed in the forebay and several vortices occurred in the sump. To suppress the clash inflow in the south and north intake channel, the “straight diversion pier + curved wing wall” and “straight diversion pier + curved wing wall + V-shaped diversion pier” were installed separately. The” symmetrical 川-shaped diversion pier” and “symmetrical 川-shaped diversion pier + circular column” was utilized to eliminate the bias flow and large-scale vortices in the forebay. Finally, the “three- sectional diversion pier”, “three- sectional diversion pier + triangle column” and “three- sectional diversion pier + triangle column + straight back baffle” was applied to decrease the vortex and asymmetric flow near the suction pipe of the sump. By attaching the rectification measure schemes in the intake channel and the forebay, the bias flow and large-scale vortex in the forebay were suppressed to varying degrees. The schemes significantly reduced the recirculation coefficient and greatly reduced the recirculation volume. By utilizing the vortex elimination measures in the sump, the vortex and asymmetric flow basically disappeared, the velocity distribution tended to become more uniform, and the flow rate distinction of each pump was smaller. The outcome can be used to provide a reference and basis for the improvement of flow pattern in similar laterally asymmetric intake pump stations. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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17 pages, 8648 KiB  
Article
Investigation of Flow-Induced Noise Characteristics in the Oblique Flow Pump
by Zhengxuan Xu, Feifei Zhao, Jia Liu, Fan Zhang, Jinfeng Zhang and Mengbin Song
Processes 2022, 10(11), 2221; https://doi.org/10.3390/pr10112221 - 28 Oct 2022
Cited by 1 | Viewed by 914
Abstract
An oblique flow pump is widely used in farmland irrigation and drainage, water transfer projects, thermal power generation, and other fields. However, unstable flow factors in the oblique flow pump easily lead to pump vibration and noise. To improve the stability of pump [...] Read more.
An oblique flow pump is widely used in farmland irrigation and drainage, water transfer projects, thermal power generation, and other fields. However, unstable flow factors in the oblique flow pump easily lead to pump vibration and noise. To improve the stability of pump operation and optimize the operating environment, it is necessary to study the flow-induced noise characteristics of oblique flow pumps. In this paper, CFD and noise simulation software are used to calculate the flow field and sound field of the oblique flow pump. The internal flow characteristics and flow-induced noise characteristics of the oblique flow pump were studied. The results show that when the flow rate of the oblique flow pump deviates from the optimal operating point, especially in the small flow rate, due to the phenomena of backflow and flow separation, more high-energy vortices are produced in the flow channel, and the vortices are distributed in a wide area, which will cause greater flow-induced noise. It is found that with the increase in flow rate, the sound pressure level of flow noise in the inlet channel gradually decreases, the sound pressure level in the guide vane region first decreases and then increases, and the sound pressure level is the lowest at 1.0Q. Generally speaking, the noise sound pressure level in the outlet channel region of the pump also gradually decreases. In addition, at the blade frequency, the radiated noise of the oblique flow pump can show dipole characteristics under various flow conditions, and the radiation level of sound pressure increases with the increase in flow rate. This paper can provide a theoretical basis for the mechanism research and control strategy of flow-induced noise in oblique flow pumps. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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18 pages, 4112 KiB  
Article
Entropy Production Evaluation within a Prototype Pump-Turbine Operated in Pump Mode for a Wide Range of Flow Conditions
by Xiaotong Yan, Kan Kan, Yuan Zheng, Huixiang Chen and Maxime Binama
Processes 2022, 10(10), 2058; https://doi.org/10.3390/pr10102058 - 12 Oct 2022
Cited by 10 | Viewed by 1160
Abstract
Inside the pump-turbine, energy is irreversibly lost due to turbulent pulsations in the high Reynolds number zone and actions of viscous forces close to the wall. The conventional differential pressure method cannot obtain specific details of the hydraulic loss within the machine’s flow [...] Read more.
Inside the pump-turbine, energy is irreversibly lost due to turbulent pulsations in the high Reynolds number zone and actions of viscous forces close to the wall. The conventional differential pressure method cannot obtain specific details of the hydraulic loss within the machine’s flow passages; on the other hand, the entropy production method can provide accurate information on the location of irreversible losses and the spatial distribution of energy dissipation. Therefore, based on the entropy production theory, this study investigates the composition and distribution of hydraulic losses under different flow conditions for a prototype pump-turbine in pump mode. Study results indicated that total hydraulic losses significantly decreased, then slowly increased with an increase in flow rate. The entropy production rate caused by turbulence dissipation (EPTD), direct dissipation (EPDD), and wall shear stress (EPWS) displayed the same variation patterns as that of total hydraulic losses, with EPTD and EPDD being the most dominating. The location of hydraulic loss within the pump-turbine’s flow domain strongly depended on flow conditions. High hydraulic losses primarily occurred in the guide vanes (GV) and draft tube under low flow rates. Under high flow conditions, however, high hydraulic losses were mostly concentrated in the stay vanes (SV), spiral casing, and GV. Hydraulic losses at low flow rates were primarily caused by flow separation within the GV flow channels, vortices in the vaneless region, and inlet flow impacts on the runner blade’s leading edge. On the other hand, large vortices within the GV and SV flow channels, GV wake flow, and unsteady flow at the spiral casing were the main contributors to hydraulic loss under high flow conditions. EPDD was mainly caused by strain rate, so it was closer to the main vortex regions, whereas EPTD was affected by turbulence intensity and had a wider distribution range in the unsteady flow. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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22 pages, 12564 KiB  
Article
Transient Characteristics of Three-Dimensional Flow in a Centrifugal Impeller Perturbed by Simple Pre-Swirl Inflow
by Ze Wang and Wei Zhang
Processes 2022, 10(10), 2007; https://doi.org/10.3390/pr10102007 - 05 Oct 2022
Cited by 1 | Viewed by 1520
Abstract
The pre-swirl inflow generated by guide vanes could improve the hydrodynamic performances of centrifugal pumps as long as the inflow matches the patterns of internal flow of the impeller. In this work, we present a numerical investigation on the internal flow in a [...] Read more.
The pre-swirl inflow generated by guide vanes could improve the hydrodynamic performances of centrifugal pumps as long as the inflow matches the patterns of internal flow of the impeller. In this work, we present a numerical investigation on the internal flow in a centrifugal impeller subjected to inflow artificially constructed with simple pre-swirling; unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations are performed at the designed flow rate with five values of rotating velocity of the inflow, i.e., Urot/Uref = −0.5, −0.3, 0.0, 0.3 and 0.5, where Urot and Uref denote the rotating and normal velocity component at the entrance of the inflow tube, respectively. The primary objective of this work is to reveal the three-dimensional characteristics of internal flow of the impeller as influenced by the superimposed pre-swirl inflow, and to identify the propagation of inflow within the impeller. The numerical data are presented and analyzed in terms of the streamline fields, the distributions of various velocity components along the circumferential and axial directions, the pressure distribution and limiting streamlines on the surfaces of a blade. Numerical results reveal that separation occurs around the leading edge of the blades and occasionally at the trailing edge, and the internal flow is more uniform in the central region of the channels. A noticeable fluctuation of both radial and circumferential velocities is observed at the outlet of the impeller as it is subjected to counter-rotating inflow, and the greatest fluctuation is close to the hub instead of the middle channel and shroud as for the co-rotating inflow. The boundary layer flow of suction surface is more sensitive to the inflow; occasional small-scale separation bubble occurs on the suction surface around the leading edge for some blades, and reattachment of separated flow is reduced for the counter-rotating inflow. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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15 pages, 2129 KiB  
Article
The Optimal Operation of Parallel Pumping Stations for Inter-Basin Water Transfer Based on the Multi-Objective Optimization of a Single Pumping Station
by Yi Gong and Bowen Zhu
Processes 2022, 10(10), 1935; https://doi.org/10.3390/pr10101935 - 26 Sep 2022
Cited by 4 | Viewed by 1437
Abstract
A nonlinear mathematical model for the optimal operation of a parallel pumping station group was established with the objective of minimizing the operation costs of the station group considering the target quantity of water extraction and flow unevenness between units of each station [...] Read more.
A nonlinear mathematical model for the optimal operation of a parallel pumping station group was established with the objective of minimizing the operation costs of the station group considering the target quantity of water extraction and flow unevenness between units of each station as constraints. The original model is decomposed into several sub-models with a single station multi-objective optimization operation with the target water lifting capacity of a single pump station as the coordinating variable. This constructed model was solved using a large-scale system decomposition dynamic programming aggregation method based on sub-system multi-objective genetic algorithm optimization. Taking the Jiangdu parallel pumping station group in the Chinese East Route of the South-to-North Water Diversion Project as a case study, the results show that under the condition of 80% water lifting load of parallel stations and 7.8 m daily average lift, the unit water lifting cost of the optimal operation of each station decreases by 4.81%, 4.81%, 19.83% and 11.06% compared with the constant speed operation at the specified angle. The unevenness of the flow of each station is 2.16 m3/s, 2.16 m3/s, 0.60 m3/s and 14.10 m3/s. The erosion of the outlet pool is small. This article provides theoretical reference for the optimal operation of the same type of large-scale inter-basin water transfer parallel pumping station groups. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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23 pages, 26276 KiB  
Article
Design and Development of Explosion-Proof Cavity of Hydraulic System Power Unit Applied in Explosion-Proof Area
by Hanzhe Chen, Dingxuan Zhao, Zhuxin Zhang, Tuo Jia, Ruoyu Zhao and Zhengkun Qu
Processes 2022, 10(9), 1824; https://doi.org/10.3390/pr10091824 - 09 Sep 2022
Viewed by 1515
Abstract
The construction machinery and vehicles, especially the explosion-proof and explosion-isolation ability of the vehicles are playing an increasingly important role in the complex and unpredictable emergency rescue field. In this paper, the explosion-proof housing of hydraulic system power unit applied in engineering machinery [...] Read more.
The construction machinery and vehicles, especially the explosion-proof and explosion-isolation ability of the vehicles are playing an increasingly important role in the complex and unpredictable emergency rescue field. In this paper, the explosion-proof housing of hydraulic system power unit applied in engineering machinery is investigated, wherein the power unit includes motor, power supply and control element. Motor-driven hydraulic pump provides the necessary power for the hydraulic system. The gas explosion process, basic parameters, flame acceleration mechanism and the theory model of gas explosion in finite space are analyzed. Relevant mathematical models of the experimental gas explosion for explosion-proof cavity are established. Furthermore, the models are analyzed by numerical method. We simulate the dynamic process of explosion by software. The analysis, examination and simulation of structural strength are conducted on the explosion-proof cavity according to the maximum explosion pressure obtained from the simulation results. The reasonable design parameters satisfying the explosion-proof requirements are obtained. The explosion-proof cavity which is processed according to the design parameters is tested. The explosion-proof performance is verified by analyzing the experimental results. According to the test standard, the impact test, thermal test, pressure test, overpressure test and propagation test under internal ignition for the cavity are conducted. The results show that the pressure test coincides with the simulation results. The remaining test results also satisfy the experimental purpose. The reasonableness of the design of the explosion-proof cavity is verified, which can meet the actual requirements of the equipment. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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Review

Jump to: Research

22 pages, 1843 KiB  
Review
Review of the Progress of Energy Saving of Hydraulic Control Systems
by Ruichuan Li, Yisheng Zhang, Zhen Feng, Jikang Xu, Xiaowei Wu, Mengnan Liu, Yuhai Xia, Qiyou Sun and Wentao Yuan
Processes 2023, 11(12), 3304; https://doi.org/10.3390/pr11123304 - 27 Nov 2023
Viewed by 1051
Abstract
In many different industrial domains, hydraulic control systems are extensively utilized. This paper examines the current state of research and the trajectory of energy-efficient hydraulic control system development. Initially, a quick introduction to the control principles of hydraulic control systems is given. Secondly, [...] Read more.
In many different industrial domains, hydraulic control systems are extensively utilized. This paper examines the current state of research and the trajectory of energy-efficient hydraulic control system development. Initially, a quick introduction to the control principles of hydraulic control systems is given. Secondly, hydraulic control systems are classified, the factors affecting the energy consumption of hydraulic control systems are analyzed, and the method of reducing its influence on hydraulic control systems is given. Subsequently, research concerning energy conservation is compiled based on the classification of hydraulic control systems. In this paper, the circuit structure of two control modes of a hydraulic control system (valve control system and pump control system) and their related control algorithms (fuzzy PID control, adaptive robust control) for reducing system energy consumption are studied. In summary, the evolution of energy-efficient hydraulic control system approaches is forecasted and projected, offering some pointers for advancing hydraulic control system study and implementation in the industrial future. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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21 pages, 4949 KiB  
Review
Review of the Research on and Optimization of the Flow Force of Hydraulic Spool Valves
by Ruichuan Li, Yuhang Sun, Xiaowei Wu, Peng Zhang, Defang Li, Jianghai Lin, Yuhai Xia and Qiyou Sun
Processes 2023, 11(7), 2183; https://doi.org/10.3390/pr11072183 - 21 Jul 2023
Cited by 3 | Viewed by 1424
Abstract
As one of the important factors affecting the stability of slide valves, the analysis and research of flow force are of great significance. In recent years, more and more experts and scholars have conducted research in this field, attempting to find methods to [...] Read more.
As one of the important factors affecting the stability of slide valves, the analysis and research of flow force are of great significance. In recent years, more and more experts and scholars have conducted research in this field, attempting to find methods to reduce or utilize the flow force of hydraulic spool valves. Flow force includes steady-state flow force and transient flow force, with steady-state flow force having the most significant impact on spool valves. The influencing factors of flow force are complex and diverse, including the cavitation phenomenon, shape of the throttling groove, and jet angle. At present, the main ways to reduce flow force are to design the structure of the spool valve, the structure of the valve sleeve, and the flow channel of the valve body. This article mainly reviews the definition, calculation methods, influencing factors, and methods for reducing the flow force of slide valves. This provides a new approach to reducing the flow force in hydraulic spool valves. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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19 pages, 2456 KiB  
Review
Review of Flow-Matching Technology for Hydraulic Systems
by Ruichuan Li, Qiyou Sun, Xinkai Ding, Yisheng Zhang, Wentao Yuan and Tong Wu
Processes 2022, 10(12), 2482; https://doi.org/10.3390/pr10122482 - 23 Nov 2022
Cited by 4 | Viewed by 3966
Abstract
The flow-matching problem of hydraulic systems is an important factor affecting the working performance and energy saving of hydraulic systems. According to the different flow-matching mechanisms, the flow-matching technology of hydraulic systems can be divided into three categories: positive flow-control technology, negative flow-control [...] Read more.
The flow-matching problem of hydraulic systems is an important factor affecting the working performance and energy saving of hydraulic systems. According to the different flow-matching mechanisms, the flow-matching technology of hydraulic systems can be divided into three categories: positive flow-control technology, negative flow-control technology, and load-sensitive control technology. In this paper, the working mechanism of flow-matching technology and the cause of energy loss are analyzed, and the research results of flow matching are introduced from two aspects of energy saving and consumption reduction and system performance improvement. In the direction of energy saving and consumption reduction, the purposes of energy saving and consumption reduction are achieved by means of multi-way valve commutation, independent inlet and outlet control, parallel replacement of shuttle valve by a cylinder piston rod controlled by pilot pressure, change of hydraulic resistance of a pressure compensating valve, improvement of the power regulation range of a hydraulic pump, and potential energy recovery. In the direction of system performance, by means of flow-forecasting system pressure change, applying flow unsaturation real-time control idea, and combining electronic control technology with load-sensitive technology, the pressure drop during transmission process and the transmission signal lag are reduced, the speed regulation interval is enlarged, fine-tuning characteristics are improved, and the response speed is increased. The research results indicate that improving the structure and the control strategy of hydraulic systems and improving the flow-matching degree of a system to achieve global matching will be a future development trend. Full article
(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)
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