bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the modal response of a full-scale 200 MW Francis turbine runner
Authors: Roig R , Sánchez-Botello X , Wiborg E , Escaler X 
Published: June 2024

Abstract
Under off-design operating conditions, the flow through hydraulic turbines presents fluidodynamic disturbances that can excite a natural frequency and provoke a resonance. Determining with precision the modal properties of the runner is thus of paramount importance. The current article presents an experimental modal analysis of a 200 MW Francis runner located in the Oksla hydropower plant in Norway. During the test, the runner was bolted to the still shaft supported by the bearings and an instrumented hammer was used to excite it. Then, several accelerometers were fixed to the band and blades to measure its modal response. Subsequently, frequency response functions between the hammer impulsive force and the vibration acceleration signals were computed to determine the natural frequencies and mode shapes of the Oksla runner. Even though the main modes corresponded to nodal diameters, other more complex modes were also identified on the blades. Nevertheless, a significant disagreement was found when comparing the experimental results with the numerical predictions from a similar but not exactly equal Francis geometry, which confirms the need to scan the actual shapes and dimensions of the runner in order to obtain reliable simulated results.
Research on the Analysis Method of Measured Pressure Data during the Transient Process of Load Rejection in Hydropower Stations
Authors: Fan Jiayi , Ma Yanmei , Zhang Jian , Du Xuan , Lin Fangzhou 
Published: June 2024

Abstract
This paper proposes a method to analyze the measured pressure data in the transition process of hydropower station. The method first separates the measured pressure data to the mean pressure and pressure fluctuation data, then divides the pressure fluctuation data into different time domain grids, and performs the confidence probability processing on the pressure fluctuation data in each time grid, and finally obtains the credible measured pressure data of transient process. In this paper, the specific implementation steps of the method are introduced by taking the results of a load rejection test of a pumped storage power station as an example.
Study on On-Line Monitoring Technique and Case Study of Pump-Storage Turbine Headcover Bolt Axial Load
Authors: Zhang Meng , Wang Qifei , Xia Yushu , Tang Lei 
Published: June 2024

Abstract
This work is based on the principle of acoustoelasticity of metallic materials, systematically studied the headcover bolt axial load on-line monitoring, the method of calibration technique based on ultrasound transit time difference and temperature, and case study. By analytical calculation, test, and finite element analysis (FEA), derived the coefficients of acoustoelasticity and temperature, and investigated the bolt thermal stress and the temperature correction method. A scheme for the on-line monitoring of pump-storage turbine headcover bolt axial load is given, providing a reference for important bolt axial load monitoring of hydropower units.
Study on sensitivity evaluation of conveyance system to unit hydraulic transient characteristics in pumped storage plant
Authors: Zhou Shun , Fan Jiayi , Zhang Jian , Ma Yanmei , Chen Taiping 
Published: June 2024

Abstract
The minimum pressure of draft tube inlet under the condition of successive load rejection is the key factor restricting the unit hydraulic transient characteristics in pumped storage plant, and the layout of conveyance system is an important factor affecting the unit hydraulic transient characteristics. To explore the influence of the conveyance system layout on the unit hydraulic transient characteristics, the author proposed a new method to evaluate the sensitivity of conveyance system layout to the unit hydraulic transient characteristics. Furthermore, the simulation analysis of two case power stations is used to verify the new method.
Study of axial hydraulic thrust and radial force characteristics of a variable speed pump-turbine unit
Authors: Wang Lei , Yu Shuang , Shang Linmin , Cao Jingwei , Wang Zhengwei , Liu Xiaobing 
Published: June 2024

Abstract
When the pump turbine does variable speed operation, it can improve the operation efficiency in the turbine mode, and it can improve the automatic frequency adjustment efficiency in the pump mode. However, the hydraulic thrust will also change when the speed changes, and the magnitude of the hydraulic thrust is crucial for the safe and stable operation of the unit. The work of this paper is to analyze the changes of the axial hydraulic force and radial force with the change of the speed by numerical simulation method. It is found that the fluctuation of axial hydraulic thrust can reach about 34 t at 398.57rpm speed, 37 t at 412.16rpm speed and 21 t at 428.6rpm speed. the fluctuation of radial force can reach about 13.78 t, 14.4 t and 12.4 t. The purpose of this paper is to use the simulation results to understand the hydraulic thrust characteristics and ensure the stability of the unit to select the appropriate speed range, provide the basis for stable operation of the unit under design conditions.
Evolution of Runner Forces during Simultaneous Pump-Trip Transient Process of Two Pump-Turbines
Authors: Ke Liu , Yongguang Cheng , Jinghuan Ding , Xi Wang 
Published: June 2024

Abstract
To ensure no cavitation and water column separation in pump-turbines, the suction heights of pump-turbines in high-head pumped-storage hydropower stations have to be decreased to about –100 m, which leads to high pressure in the draft-tube. During the pump-trip transient process of pump-turbines, the positive water hammer wave in draft-tube superposing the initial high pressure may cause an imbalance of rotating parts and even a lifting-up accident. To quantify the runner forces, two typical transient processes, with and without guide-vane closure after the simultaneous power-off of the two pump-turbines in one hydraulic system, were simulated by using the one-dimensional and three-dimensional coupled (1D-3D) computational fluid dynamics (CFD) method. The results show that the maximum upward axial force on the runner during the process without guide-vane closure (runaway) is significantly higher than that during the process with guide-vane closure. Two significant maximum upward axial forces were observed during the runaway process, and they were around the zero and the valley speed moments. The main causes are the pressure decrease in the runner’s high-pressure zone owing to high-speed bypass flows, and the spiral-case negative water-hammer wave and draft-tube positive water-hammer wave caused by discharge rise. However, the draft-tube positive water hammer wave superposing the high pressure did not cause the maximum axial force. The above two moments of highest axial forces during the runaway process and the proper guide-vane closure rule deserve special attention in the design and operation phases.
Numerical study of rotor-stator interaction in variable speed reversible pump-turbine in turbine mode at low head
Authors: Rode B R , Kumar A , Segoufin C , Laurant Y 
Published: June 2024

Abstract
Pumped storage hydropower (PSH) offers the cost-effective storage of large quantities of energy with high efficiency. Reversible pump-turbines (RPT) are used in PSPs having large head variations and where variable speed operation can enhance its efficiency and grid stability. The RPT may experience higher fatigue and vibrations due to hydraulic instabilities caused by pressure fluctuations in the vaneless space between runner blades and guide vane interaction, known as rotor-stator interaction (RSI). Because of this instability, the local components of the powerhouse vibrate severely. Therefore, there is a need to study the pressure fluctuations caused by RSI in the variable speed RPTs. The present numerical study focuses on the pressure fluctuations due to RSI in turbine mode conditions having low available head. The present study used a reduced scale high-head variable speed RPT model, and the SST k-ω turbulence model was used to carry out numerical calculations. The analysis was performed at the best efficiency point and low head operating conditions having optimized rotational speed. The analysis showed that the main source of pressure fluctuations in the RPT at all operating conditions is the RSI, where the dominant frequency is BPF and its harmonics.
Vibration and noise of a high head pump turbine: analysis and improvement
Authors: Guan Z W , Jia W B , Leng Z J , Chen J , Wang Z N , He Q Y , Liang Q W 
Published: June 2024

Abstract
In a high head pumped storage power plant with 9 blades and 20 guide vanes, vibration and noise problems occurred with characteristic frequency of 2 times the blade passing frequency (BPF). It is found that the first main frequency of pressure pulsation in the vaneless zone is also 2BPF with a two-nodal diameter mode by using three dimensional unsteady numerical method, which indicates that the main cause of vibration and noise is rotor stator interaction (RSI). By increasing the radial gap of the vaneless zone, the amplitude of pressure pulsation in the vaneless zone is reduced by 40%-50% according numerical results. One unit in the power station was refurbished. It was shown that the pressure pulsation in the vaneless zone was reduced by 40%, and the head cover vibration was also reduced, and the noise in the turbine pit was reduced by 6 dB according the field test results. So the numerical analysis and prediction here are very accurate, and the vibration and noise problems of this power station are caused by RSI.
Simulation analysis of runaway process of tubular pump and comparison of site test
Authors: Zhongwei He , Linfeng Shu , Chengjun Li 
Published: June 2024

Abstract
To investigate the transient characteristics of tubular pumps during runaway, we developed a three-dimensional model of the pump and its flow channel. Using this model, we conducted a CFD simulation to analyse the three-dimensional transient process of the tubular pump’s runaway, and obtained the internal and external characteristic parameters of the pump. By comparing the results of the site test and the numerical simulation, we verified the correctness of the speed, flow, pressure pulsation, and eccentric zone during the runaway process of the numerical simulation. This verification provides technical support for the subsequent pump station operation.
Numerical investigation on slip velocity characteristics of gas-liquid two-phase flow in a multiphase pump under different blade tip clearance
Authors: Li Chenhao , Wu Xitong , Luo Xingqi , Feng Jianjun , Zhu Guojun , Wang Xiaohang 
Published: June 2024

Abstract
It is significant to explore the slip velocity characteristics of two-phase in blade tip clearance (BTC) of multiphase pump for improving semi-open mixed-flow pump performance. On the ground of the Euler-Euler inhomogeneous model, a gas-liquid mixed-flow pump was taken as the research object. Using CFX software to simulate the flow field in the multiphase pump with conditions of the inlet gas void fraction (IGVF) are 10%, 20% and 30%. The slip velocity characteristics of gas-liquid two-phase in mixed-flow multiphase pump with different blade tip clearance sizes (BTCS) were analyzed. The results show that there is obvious slip velocity on blade leading edge (L.E.), trailing edge (T.E.) and pressure side (PS) of BTC of mixed-flow pump impeller. When BTCS is small, the slip velocity on the tip pressure side has little change along flow direction, but with the increase of BTCS, slip velocity on the tip pressure side will gradually increase. There is a positive correlation between slip velocity and the pressure gradient. The research results can provide significant guidance for optimization design of semi-open mixed-flow multiphase pump.
Coherent structures decomposition of internal flow in the double-suction centrifugal pump impeller
Authors: Zhang Wenlu , Deng Shuwen , Wang Tao , Jiang Bo , Wang Yuchuan 
Published: June 2024

Abstract
In order to understand the unsteady flow phenomenon of the centrifugal pump, the dynamic mode decomposition method (DMD) is introduced to extract the three-dimensional coherent structure of the rotating flow field in the impeller passage under three different working conditions of the double-suction centrifugal pump. The time series collection of flow field is constructed by CFD numerical simulation, and the approximate matrix characteristic parameters and different modal data are solved. The analysis results show that the position, form and spatial-temporal evolution of the coherent structure can be accurately captured by DMD method corresponding to a single frequency in the double suction pump. For the temporal evolution, the coherent structure corresponding to low frequency is the most stable and dominate the unsteady flow. For the spatial evolution, the coherent structure corresponding to even-fold rotational frequency mostly occurs near the pressure side of the blade at the outlet of the impeller, and the coherent structure corresponding to odd-fold rotational frequency is mostly located in the flow field inside the impeller or near the blade surface.
Transient vortical structure evolution under part-load condition in a high-power double-suction centrifugal pump based on Liutex method
Authors: Deng Qifan , Pei Ji , Wang Wenjie 
Published: June 2024

Abstract
In order to investigate the evolution of vortical structures inside a high-power double-suction centrifugal pump, the flow fields were solved numerically by the SST k-ω turbulence mode. After experimental validation, the Liutex/Rortex method was adopted for identifying vortices for each step from the numerical results, and the enstrophy was adopted to present the kinetic energy that vortical structures contained. The vortical structures at different seconds were obtained, and the vortices evolution was figured out. The results indicate that: the wake vortex was the dominant type inside the volute. Vortical structures at the impeller inlet evolve periodically. The interactions between the impeller leading edge with suction ribs and the blade trailing edge and volute tongues were critical factors for vortex evolution. Vortical structures mainly formed at the impeller inlet near the blade suction side. The suction rib would decrease the absolute rotational intensity around it, but the relative local rigid vortex would keep a high intensity. Due to the suction rib and volute tongues, the vortices variated with a period of 1/2T.
Effect of airfoil trailing edge up on the performance of gas-liquid multiphase pumps
Authors: Nan Haozhi , Han Wei , Li Rennian 
Published: June 2024

Abstract
In this study, the impact of blade trailing edge structure on the performance of multiphase pumps was investigated. The modification parameters of the impeller blade airfoil were characterized by defining and adjusting the chord length ratio l/l
0 and deflection k, based on the design methodology employed for wing flap lifting devices. The impeller blade airfoil was modified using the trailing edge up design approach. Comparative analysis was conducted to evaluate the effectiveness of elevating the trailing edge of the airfoil in improving flow channel blockage, reducing turbulent energy at the impeller outlet, minimizing energy dissipation, and ultimately enhancing the efficiency of multiphase pumps. Remarkably, a maximum efficiency improvement of up to 3.04% was observed when the inlet gas content reached 70%.
Numerical study on the flow-induced vibration of a high-pressure-jet pump on a dredger and corresponding impeller optimization
Authors: Hu Jingzhao , Cao Lei , Zhuang Haifei 
Published: June 2024

Abstract
Trailing suction hopper dredgers are usually equipped with high-pressure-jet pumps, which provide high pressure water to improve dredging efficiency. In a newly built trailing suction hopper dredger, the high-pressure-jet pump encountered serious vibration problem. In this study, unsteady Reynolds-averaged Navier-Stokes equations were solved with Shear Stress Transport k-ω turbulence model to carry out pump-pipeline matching analysis, and the causes of flow-induced vibration were discussed. The impeller was correspondingly optimized by increasing the blade number and moderately decreasing the blade inlet setting angle and wrap angle. The optimization results show that the high-pressure-jet pump works in the high-efficiency zone both for the high-speed dredging process and low-speed hopper discharging process, and the time-average value and amplitude of the hydraulic radial force drops by more than 30% under the required working condition, which effectively mitigates the flow-induced vibration.
Numerical Simulation of Unsteady Cavitation at the Tongue of a Centrifugal Pump
Authors: Zhou Wenbo , Zhang Yongxue , Yuan Zhiyi , Zhu Jianjun , Tan Zheng 
Published: June 2024

Abstract
The flow separation at the tongue of the centrifugal pump will cause a sharp reduction of local pressure, thus inducing the cavitation phenomenon, which hurts the stable operation of the pump. This article focuses on the centrifugal pump as the research object. The Delayed Detached Eddy Simulation (DDES) method based on the SST turbulence model was employed to numerically simulate the cavitation at the tongue of the centrifugal pump. The typical characteristics and unsteady changes of cavitation were observed and studied, and the pressure at the tongue position was monitored for flow rates of 1.36 Q
0 and 1.54 Q
0. The results show that, in the cloud cavitation stage, the area of the cavitation bubble presents periodic changes, the main frequency of the cavitation area pulsation is twice the axial frequency, the periodic shedding of the cavitation bubble is caused by the attached vortex (re-entrant jet) and the pressure gradient, and the wall attached vortex will periodically shed and break. The high intensity vortices generated by flow separation at the tongue will change periodically with the rotation of the blade. With the increase of inlet flow, the pressure pulsation at the tongue increases, and the shedding and collapse of the cavitation bubble will enhance the pressure pulsation.
The influence of the gap width of the blade on the performance of the mixing pump
Authors: Li R N , Xing Y F , Zhang W Y , Xue T Q , Hou Y Y , Zhao L L , Bai L , Yang T , Yang Y B , Dong Y F 
Published: June 2024

Abstract
The spiral axial flow gas-liquid mixed pump has some problems, such as unsteady flow and sharp decline in performance, when it runs in the biased condition with high gas content. Based on the principle of fluid flow and the design concept of slot drainage, a slit blade is proposed in this study to improve the degree of gas-liquid separation inside the mixing pump. The slit connects the pressure surface of the blade of the mixing pump with the suction surface. The pressure difference between the pressure surface and the suction surface leads to the generation of slit jet, which plays a “blowing” role in the adhesion of the gas phase on the suction surface inside the mixing pump. And make the stagnant air mass in the flow passage move again, so as to slow down the gas-liquid separation in the mixed transport pump. This study provides theoretical reference for the design and optimization of spiral axial flow gas-liquid mixed pump.
Influence of offset blade on pressure fluctuation in a centrifugal pump under different conditions
Authors: Zhang Yi , Li Guoping , Chen Changsheng , Ma Zhenlai , Chen Biwen , Gao Bo , Lu Yangping , Gao Yuhan , Tan Lei 
Published: June 2024

Abstract
In this paper, the pressure fluctuation under different working conditions of hydrofoil blade impeller (AF), offset blade impeller (SP) and offset winglet impeller (DAF) were measured and the influence of different structures on pressure fluctuation was analyzed. The results show that the discrete frequency caused by rotor-stator interaction (RSI) between impeller and tongue is the blade passing frequency (fBPF
) and its harmonic frequency. Pressure fluctuation amplitude of blade passing frequency is obviously suppressed by offset blade. The value of pressure fluctuation of DAF is small near the tongue under small flow rate, and the energy suppression effect is obvious. With the increase of flow rate, the fluctuation energy of DAF increases gradually, and that of SP decreases gradually.
Practice of first water filling operation of super-high head diversion channel in YangJiang storage power station
Authors: Zhen Peijiang , Cai Mingzhi , Yan Liang , Le Wang 
Published: June 2024

Abstract
In order to summarize the key points of the first water filling operation of 800-meter-class reinforced concrete waterway, and provide reference for the water filling operation of similar pumped storage power stations in subsequent power stations, this paper summarizes and analyzes the first water filling operation of Yangjiang pumped storage power station from the aspects of waterway characteristics, water filling procedure, operation key points and risk control, and explores the standardized flow of the first water filling operation of the pumped storage power station combined with practice to ensure the first success of water filling. This paper focuses on the optimization and implementation of the reverse water filling scheme of the lower adit in the upstream waterway. At the same time, the problems in the process of water filling operation are analyzed, and improvements and suggestions are put forward.
Anti-seepage measures for the upper reservoir of one pumped-storage power station
Authors: Cheng Yanan , Wang Jue , Zhao Long 
Published: June 2024

Abstract
Seepage control plays an important role in the design of pumped storage power station. In this paper, the seepage characteristics and geological conditions of the upper reservoir of a pumped storage power station are analyzed, and the natural seepage of the upper reservoir is calculated. According to the characteristics and amount of leakage, the upper reservoir can be controlled by local seepage control scheme, and the anti-seepage treatment scheme of the south reservoir bank is compared and analyzed. After the local anti-seepage treatment of upper reservoir, the daily seepage volume decreased from 5585m3/d to 2304m3/d, which indicates that the selected anti-seepage scheme is suitable. This paper can provide useful reference for similar projects in the future.
Research on hydraulic variable pressure pumped compressed air energy storage system
Authors: Yang Biao , Li Deyou , Fu Xiaolong , Liu Haibo , Wang Hongjie 
Published: June 2024

Abstract
To cope with the problems of large pressure variation, large throttling loss of the existing pumped compressed air energy storage system, a new hydraulic variable pressure pumped compressed air energy storage system is proposed in this paper. The key components include a variable-speed pump turbine, a hydraulic potential energy transfer device and a water-gas compatible tank. For the proposed system, a thermodynamic model is established. And its correctness is verified by comparing it with measured data. Then, the charging and discharging simulation is carried out. Finally, the variation process of each key parameter of the system is revealed. It is found that the energy efficiency of the system is high, reaching 58.2%, and the energy density is 0.36 kW·h/m3. Through the hydraulic potential energy transfer device, the pressure variation of 2.2 MPa in the tank is converted into the head variation of about 60 m (0.6 MPa) at the variable-speed pump turbine, which improves the operating efficiency of the hydraulic machinery. This technology can provide support for the development of energy storage technology.