bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of self-oscillation stability of a pump-turbine in the S-shaped regions of characteristic curves
Authors: Chen X W , Lai X , Chen H Y , Lin Y F , Liu K , Cheng Y G 
Published: June 2024

Abstract
The hydraulic oscillation of pumped-storage power station (PSPS) affects the safe and stable operation of the power station. The S-shaped characteristic curves of pump-turbine may sometimes result in instability in speed-no-load operation. To investigate the instability mechanisms and identify the main factors that affect stability, this paper used the overall matrix method to establish a self-excited oscillation calculation model of a PSPS and analyzed the stability characteristics and influencing factors of the S-shaped regions of the speed-no-load opening. The results show that when the slope of the characteristic curve is negative, the natural frequency attenuation factors of the system are negative, demonstrating stability. When the slope of the characteristic curve is positive, the system remains stable if the slope is large. However, if the slope of the characteristic curve is below a certain value, which may lead to instability. Increasing the inlet valve resistance and appropriately changing the valve layout position can enhance the stability of the system. The damping surge chamber fluctuations have no impact on system stability. The study also found that the stability regions of the S-shaped regions are related to the slope of the characteristic curve, the unit operating discharge, and the value resistance coefficient.
The Pump-turbine Hydraulic Performance Research, Model Test and Operation in Yangjiang Pumped Storage Power Station
Authors: Xiaolong Yang , Huanmao Wang , Ming Liu , Chao Wang 
Published: June 2024

Abstract
The Yangjiang Pumped Storage Power Station (PSP) is the largest unit rated output PSP that has been built in China, with a maximum water head of nearly 700m and a unit capacity of 400MW. The ultra high water head and its large range of the PSP means a significant difficulty during the dydraulic research and development of the pump-turbine. In this paper, it is introduced on model test and results in the EPFL and IWHR. It is studied on energy performance, cavitation, pressure pulsation and “S” characteristic of pump-turbine with splitter blade. The unit data analys after put into operaton indicat highly hydraulic stability and relative tiny vibration, which just verify the model test. As the model and prototype results show that Yangjiang pump-turbine is outstanding in various indexes and quite excellent in comprehensive hydaulic performance.
Analysis of flow characteristics of a pump turbine under the transient condition of 75% load rejection
Authors: Zhao Qiang , Jin Faye , Cao Jiali , Wu Huanyu , Luo Yongyao 
Published: June 2024

Abstract
In this study, the flow calculations for a pump turbine under the transient condition of 75% load rejection was conducted. The model incorporated a boundary layer on the surface of the guide vane, with the node coordinates of each element in the boundary layer region being updated. This approach ensured the stability of the boundary layer mesh. Experimental measurements provided parameter curves for inlet pressure, outlet pressure, runner speed, and guide vane opening over time. The pressure fluctuation at each monitoring point was compared with the experimental data, and a good agreement was found. Additionally, the variation curve of the axial hydraulic thrust of the head cover and the pressure distribution nephogram of the head cover at typical moments were analysed. The results of this study could be used as a reference for the safe and stable operation of pumped-storage power stations.
Numerical study on the performance characteristics of a high-head pump turbine based on the GEKO model
Authors: He L , Gao Z X , Zhao L C , He L , Wang W P , Meng L , Liao C L 
Published: June 2024

Abstract
As the most mature large-scale energy storage facility in the world, the core equipment of pumped storage power stations, the pump-turbine, is currently developing towards high head and large capacity. And the computational fluid dynamics method (CFD) is one of the most important means to research the internal flow mechanism of pump turbines and optimize the hydraulic performance. Turbulence models play an important role in the study of the flow field. Many high-performance RANS turbulence models (such as SST) cleverly combine the advantages of various models to achieve high precision, but they are not universal and their applicability and accuracy for complex flows are still limited. The Generalized k-ω (GEKO) model model may be a good choice among eddy viscosity models as users can adjust the free parameters according to their specific applications. In this study, the internal flow field of pump turbine is numerically simulated by GEKO model with various values of the separation parameter C
SEP and the curvature correction parameter C
CURV compared with experimental results. The calculation results show that the parameter settings of C
SEP and CCURV in GEKO model have a direct impact on the numerical calculation results. The parameter modification of GEKO model has the potential to improve the adaptability and accuracy of turbulence model, and is useful for improving the engineering application of turbulence model.
A Review of the Recent Research on Hydraulic Excitation-induced Vibration in Hydropower Plants
Authors: Yu Xianhao , Zhang Shaozheng , Zhang Xianyu , Yin Xilong , Qiu Wei , Wang Zhengwei , Lin Qianqian 
Published: June 2024

Abstract
Hydraulic excitation force has an important influence on the operation of pumped storage power station. The hydraulic excitation force acting on the structural components of the unit will not only cause the vibration of the unit and affect the stability of unit operation, also cause the vibration of the power plant and the geological structure, resulting in adverse effects such as noise. Based on the research on the unit and geological vibration caused by hydraulic excitation of pumped storage power station, the causes, classification methods and examples of the influence on the operation of pumped storage power station are analysed. The mechanism of hydraulic excitation force acting on different operating conditions of the unit is compared, then the research progress on the vibration of power house considering loading hydraulic excitation force is summarized. The study on geological vibration of pumped storage power station is listed. Meanwhile, it is pointed out that the development of the method of taking the unit, plant and geological structure as the overall research object has an important impact on the construction of pumped storage power station.
The Influence of Blade Wrap Angle on the Internal Flow Field and Hydraulic Performance of Double-Suction Pump for Yellow River Pumping
Authors: Yan L M , Han W , Tian Y P , Yang X , Zhou J P 
Published: June 2024

Abstract
Analyzing the influence of blade wrap angle on the internal flow field and hydraulic performance of the pump, five different blade wrap angles were designed. Based on RNG k-ε and DPM were used to conduct a steady-state numerical simulation of impellers under the same conditions and different sand volume fractions, respectively. The results show that as the blade wrap angle increases, the flow separation and vortices in the impeller flow passage also decrease, and the flow is closer to the blade profile, but the friction loss in the impeller flow passage also increases. There is an optimal blade wrap angle to maximize the pump head and efficiency. By increasing the wrap angle of blade, the low-pressure zone at the blade inlet area increases, the high-pressure zone at the outlet decreases, and the low-speed zone within the impeller decreases, increasing the outlet velocity. When the sand volume fraction is less than 5%, the effect of sand volume fraction on the hydraulic performance of the pump is not obvious. When the sand volume fraction is more than 5%, the change of wrap angle of blade has a significant effect on the hydraulic performance of the pump.
Rotor-dynamic study for high pressure multistage centrifugal pump
Authors: Liu X F , Ma W S , Chen Y , Xiao F , Su J D 
Published: June 2024

Abstract
Rotor-Dynamic behavior were closely related to the reliability, operability and cost effective for high pressure multistage centrifugal pump. The middle sealing sleeve, high-pressure sealing sleeve, front and rear rings of the impeller of the pump set were studied in this paper, by establishing a theoretical calculation model, numerical calculation methods. The leakage, radial force and tangential force of those seals under different working media and different sealing gaps were ccalculated in detail. The results showed that the sealing performance and dynamic characteristics were influenced by working medium and the sealing gap. The working medium had little effect on the radial force and tangential force of the middle sealing sleeve and high-pressure sealing sleeve, while with a greater effect on the front and rear rings of the impeller. The radial force of the middle shaft sleeve was closed with the sealing clearance. As the seal gap was 0.5mm, negative stiffness at low and high frequency whirlpools was more easily occured. With the gap increasing, the unbalanced response of the rotor increased significantly.
Effect of Blade Thickening Law on the Internal Flow Field and Hydraulic Performance of Double Suction Pumps for Yellow River Pumping
Authors: Yang Xiang , Rennian Li , Tian Yaping , Zhou Juping , Yang Shiqi 
Published: June 2024

Abstract
The thickness of the blades is a fundamental parameter of the impeller and has a substantial impact on the performance of the pump. With the other geometric parameters of a centrifugal pump fixed, six kinds of impellers with different blade thickness were designed. Numerical simulations of the pumps were performed with Fluent under six different operating conditions based on the RNG k-epsilon equation and the SIMPLE algorithm. The hydraulic performance of the pump and its external characteristics were analysed based on the internal flow field to understand the relationship between blade thickness and performance. The results have showed that the hydraulic performance of the pump increases with the backward movement of the maximum thickness of the blade; Under the same sand concentration, the efficiency increases slightly with the increase of blade thickness within a certain range;With the increase of blade thickness, the turbulent kinetic energy loss of the pump under design operating conditions increases continuously; The thickening rules of schemes A1 and B can improve the hydraulic performance of the pump and the transport capacity of the sediment laden two-phase flow. That is, on the premise of meeting the structural strength of the blades, selecting a reasonable blade thickness can ensure that the double suction pump has good hydraulic performance.
Analysis of pressure pulsation in a multi-stage double suction centrifugal pump
Authors: Peng Wenjie , Pei Ji , Yuan Shouqi , Wang Wenjie 
Published: June 2024

Abstract
Pressure pulsation is a common phenomenon, which results from different causes. The intenser pressure pulsation occurs in the pump, the severer the damage to the pump. In the paper, with the assistance of detached eddy simulation method, the characteristic of pressure pulsation in the multi-stage double suction centrifugal pump is studied to understanding the internal flow circumstance. The results reveal that the pressure pulsation intensity reaches the maximum at blade trailing edge, which propagates to the tongue region of forward flow channel and double-volute under the low rates. Furthermore, it can be concluded that the pressure pulsation of region with obvious rotor–stator interaction between rotating impeller and stationary volute is generally larger at low flow rates. The pressure pulsation near the suction side of blade trailing edge shows the feature of broadband frequency and with increasing flow rate the bandwidth of broadband decreases drops rapidly except BP1. Due to the influence of the number of impeller blades, the dominant frequency of monitoring points in the inter-stage flow channel and the volute is basically located at a frequency that is twice the blade frequency. Meanwhile, because of the symmetry of the geometric structure of the reverse flow channel, the pressure pulsation curve changes of its internal monitoring points are similar under the same flow rate.
Analysis of Flow Fluctuation of Confined Backward-Facing Step Based on Pulsation Tracking Network Method
Authors: Liu Qiang , Lu Jiahao , Pan Jiale , Guang Weilong , Tao Ran , Zhu Di , Xiao Ruofu 
Published: June 2024

Abstract
Backward-facing step is a common flow model in hydraulic machinery. Its main feature is that there is a sudden expansion structure at the downstream of the flow channel, which causes the flow instability and is easy to form a vortex behind the sudden expansion section. At present, there are many studies on backstage step flow, but the dominant frequency fluctuation of its flow information has not been noticed. Based on the pulsation tracking network (PTN) method, the numerical simulation of a typical backstage step flow is carried out in this paper. The numerical simulation results are in good agreement with the experimental results. The results of numerical simulation are analyzed in frequency domain by using FFT to obtain the main frequency distribution of flow information on the typical section of the backstage step flow and the distribution of pulsation amplitude at each frequency. It explores a new direction for future research.
Investigation of flow-induced sound source generation in a centrifugal pump
Authors: Yuan Zhiyi , Zhang Yongxue , Zhou Wenbo , Zhang Jinya , Zhu Jianjun 
Published: June 2024

Abstract
This study investigates the mechanism of sound source generation in a centrifugal pump under different flow conditions. The calculated results are in good agreement with experimental data by employing the delayed detached eddy simulation and flow-acoustic coupling method to compute the flow-induced noise. Based on the vortex sound theory and vorticity binary decomposition, the sound source (STA) is divided into a shear-induced source (STS) and a rigid rotation-induced source (STR). The results show that the sound source induced by shear is the main factor. The fluctuation amplitude of STS can be nine times larger than STR at monitor point near the tongue under the design flow rate condition. There is a mutual cancellation effect between the STS and STR. The fluctuation amplitude of STA at the blade passing frequency is 86% of STS at monitor point near the tongue under high flow rate conditions, indicating that sometimes rigid rotation can suppress noise generation.
Design and Performance Prediction of a Vortex Pump Based on CFD for High Concentration Sludge Dredging
Authors: Zhuang H F , Liu M M , Cao L 
Published: June 2024

Abstract
Aiming at solving the problems of clogging and severe wear of the delivery pump in the sludge dredging project, a design method for a vortex pump was summarized. An open impeller and a cross shaped blade was designed with good passing ability, simple structure, and easy maintenance. The volute flow path profile of the vortex pump was designed as a spiral, and the relationship between the width of the vaneless cavity and the diameter of the impeller was established. Based on CFD, the external characteristics of the DRC45-200-VLS vortex pump were simulated and predicted, with a flow rate of 600 m3/h, a head of 20 m, and a water efficiency of 50%. The effects of medium viscosity, solid phase distribution, and gas phase distribution on the flow field of the vortex pump were analyzed. The results showed that the designed vortex pump had good adaptability to transport high concentration sludge and aerated sludge. Combined with a municipal sludge dredging project, a vortex pump transportation scheme for high concentration sludge dredging was formed.
Numerical Simulation of Solid-Liquid Two-Phase Flow in Pump
Authors: Xia Guosheng , Zhang Haili , Zhang Yang , Jiang Wei , Fan Honggang 
Published: June 2024

Abstract
This paper is based on EDEM-FLUENT coupling calculation, the solid-liquid two-phase flow at pump is analyzed. Three kinds of solid phase volume concentration and three solid phase particle diameters are given respectively, and the solid-liquid two-phase flow numerical simulation of the internal flow field of the pump is carried out. The position distribution of solid particles in the flow field and the change of particle average velocity with time and the distribution of particle velocity are analyzed. The results show that the inlet of the runner and the pressure surface of the blade are the concentrated distribution areas of particles. With the increase in particle concentration, the particle distribution at the outlet of the volute is more uniform. The average velocity of particles at different particle concentrations varies similarly with time, but the average velocity of particles increases with the increase of concentration. With the increase in particle size, the average velocity of particles decreases, but the velocity value with the largest proportion of particles becomes larger.
Study on the coupling vibration characteristics of vertical unit and plant of large underground pumping station for water transfer project
Authors: Lu Shaopeng , Wang Tao , Zhang Haili , Wang Yuchuan , Fan Honggang 
Published: June 2024

Abstract
To investigate the coupled vibration characteristics of vertical pumping unit and plant structure of large underground pumping station for water transfer project, the coupled vibration differential equations are established. The structure nodes of are simplified from horizontal direction and vertical direction respectively by force. The structural parameters and load parameters of the model are analyzed and calculated, and the vibration response of each node are calculated by solving the vibration differential equations. A spectral analysis of white noise is applied to the coupled model, and the natural frequencies and vibration structures of dominant vibration modals are obtained. Research indicates that the vertical vibration modes of the system exhibit a relatively low coupling degree with the plant structure. The shaft system and the plant structure mainly display combined vertical vibrations, while the plant structure predominantly exhibits independent vertical vibrations. This implies that vertical vibrations are jointly influenced by shaft system stiffness and plant structure properties. In horizontal vibration modes, a strong coupling characteristic is observed between the upper structure of the pump station unit and the plant structure. This is primarily manifested as coupled vibrations between the support and the plant structure, which are collectively influenced by support constraints, shaft system stiffness, and plant structural properties.
Validation of the steady and unsteady simulation based on an axial-flow pump
Authors: Nguyen Duc-Anh , Kim Sung , Jeong Soon-Young , Kim Jin-Hyuk 
Published: June 2024

Abstract
An axial-flow pump offers high flow rates and efficiency with low power consumption, making it ideal for applications that require transferring the large volume of fluid. Applying the numerical simulation in predicting hydraulic performance, analyzing the phenomena, and optimizing the design of the axial flow pump is very cost-effective and flexible. This study is performed to clarify the difference between steady and unsteady simulations based on the axial flow pump. Numerical simulations are carried out using the steady and unsteady Reynolds-averaged Navier-Stokes (RANS and URANS) equations and a shear stress transport reattachment modification turbulence model with small y+ values at all wall surfaces. To show the accuracy, numerical simulations are analyzed and compared with testing results. The difference in steady and unsteady simulations is presented by a detailed analysis of the flow field under the deep stall condition. The result shows that the numerical and testing results are in good agreement with each other. However, the unsteady results are more accurate than the steady results, especially in the saddle zone. Under deep stall condition, it is difficult to accurately predict the hydraulic performance and fluid flow characteristics inside the axial flow pump through steady simulation because of the time-dependent flow.
Research on hump characteristics improvement of low-mid specific speed high-power centrifugal pump
Authors: Zheng Yang , Meng Long , Tian Yajuan , Wang Xin , Zhang Chiye , Chen Yuhang 
Published: June 2024

Abstract
The hump phenomenon is a typical hydraulic instability of centrifugal pump. The hump curve is easily found on H-Q characteristic curves of centrifugal pump at low flow conditions. Hump phenomenon causes large vibration and noise and affects the unit stability of star-up process. The impeller model with specific speed ns=100 was used an initial impeller for the high-power centrifugal pump to be developed, and the meridian flow channel keep unchanged. The impeller geometry, the blade profile, blade exit edge, wrap angle, inlet blade angle were optimized to improve hump characteristics. The 3D pump model with the initial and optimized impeller were simulated to obtain the H-Q characteristic curve. The numerical simulation results show that the inlet secondary reflux is significantly weakened, energy characteristics and hump margin of the optimized impeller are obviously improved compared with the initial impeller. The optimized impeller was also tested on the model test system to verify the hump margin. The test results demonstrate that the optimized design considerably improve the centrifugal pump’s hump margin. The results of simulations and model tests verified that impeller optimization was a suitable and efficient way to enhance the hump characteristics. The result provides design reference for long-term safe and stable operation of low-mid specific speed high-power centrifugal pump.
The Study of Using the Inducer to Improve the Cavitation Performance of a Centrifugal Pump
Authors: Ma L L , Wang C , Chen Y , Wang B H , Yu D H , Yang Y C 
Published: June 2024

Abstract
To improve the cavitation performance of a single-stage, single-suction centrifugal pump, this study compared the effects of an equal-pitch inducer and a variable-pitch inducer. Experimental results revealed that the NPSH3 of the pump without an inducer is 4.6m for operation at Q=80m3/h, while with an equal-pitch inducer and a variable-pitch inducer are respectively 2.6m and 2.2m. Both two inducers significantly increase the shut-off heads, while the BEP shift towards smaller flow rates, with the maximum efficiency value reduced by about 3%. The CFD simulation analysis show that when the inlet total pressure is greater than 4m, the equal-pitch inducer has better anti-cavitation performance, while the variable-pitch angle inducer has a better inhibitory effect on cavitation development which the inlet total pressure is less than 4m. To further enhance the pump’s cavitation performance, filing blade inlet suction side of the variable-pitchinducer is necessary to reduce the NPSH3 from 2.2m to 1.7m, resulting in a 22% improvement in cavitation performance.