bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on flow-induced radiated noise of twin-screw pumps based on the Lighthill acoustic analogue theory
Authors: Shen Jiantao , Yang Weixing , Pan Weifeng , Cheng Li
Published: October 2024

To optimize the control of twin-screw pumps (TSP), it is essential to ensure performance while simultaneously preventing noise levels from exceeding specified limits. In order to investigate the flow characteristics and the mechanism of flow-induced radiated noise under various operating conditions, a coupled numerical simulation approach using Computational Fluid Dynamics (CFD) and Computational Acoustics (CA) was employed, and the findings were validated through experiments. The study reveals that the highest sound pressure levels of radiated noise occur near the rotor outlet surface, and the dynamic-static interference at the rotor-boundary interface is the primary cause of flow-induced noise in TSP. The flow-induced noise in TSP exhibits dipole characteristics, with the overall sound pressure level gradually increasing and then sharply rising with the increase in rotational speed (or flow rate). It stabilizes near the design operating point and continues to increase steadily with further increases in rotational speed (or flow rate). Modal testing using a dual-distributed measurement technique highlights significant interference effects between the rotor inlet and the dynamic rotor for the first two Blade Passing Frequencies (BPF) in TSP. The results of this study provide a theoretical foundation for the low-vibration and low-noise design and operation of TSP.
Study on pressure fluctuation characteristics of the mixed-flow pump with the tandem misaligned blade structure
Authors: Wu Zhijian , Li Chenhao , Luo Xingqi , Zhu Guojun , Wang Like
Published: October 2024

As supporting equipment for deep-sea oil and gas resource exploitation, how to improve the transmission performance and stability of the impeller of the mixed-flow pump (MFP) has become a key technical problem. This paper focuses on studying the impeller blade of the MFP. Based on the blade optimization technology, four different tandem misaligned blade (TMB) angle schemes of α=0°,15°,45°,75° are proposed. The SST k-ω turbulence model is used to simulate the different blade angles under the pure liquid condition. The pressure pulsation of the MFP and the blade load distribution are studied. This result show that the TMB structure increases the pressure fluctuation inside the MFP. The pressure coefficient inside the impeller exhibits a more consistent pattern at an angle of α=45° compared to other angles, and the internal flow field of the MFP exhibits most stable. From this analysis of blade load distribution, TMBs have a greater effect on the pressure surface of the front blade of the MFP. When α=15°, the best pressurization performance of the MFP. This study may serve as a benchmark for subsequent iterations of optimizing the MFP’s model and hydraulic design.
Research on turbulence model parameters for the prediction of waterjet propulsion pump hydrodynamic performance
Authors: Wang Jun , Fan Sheming , Cai Youlin , Meng Kuiyu , Chen Haoyang
Published: October 2024

The hydrodynamic performance of waterjet propulsion pumps has an important impact on improving the speed of waterjet propulsion ships. High-precision prediction of the hydrodynamic performance of water-jet propulsion pumps based on CFD is of great significance to improving the pump design quality. Based on the Reynolds-averaged Naiver-Stokes equation, this paper conducts a grid-independence verification on a water jet propulsion pump based on hydrodynamic test data, uses the Latin hypercube sampling method to generate SST k-ω turbulence model parameter space calculation samples, performs steady-state calculation on all samples, analyzes the sensitivity of changes in the parameters of the turbulence model to the prediction of the external characteristics of the waterjet propulsion pump, and finally obtains the influence of changes in the parameters of the turbulence model on the prediction of the external characteristics of the pump. Among them, the sensitivities of the three parameters β *, β1 and a1 are higher. The results show that the prediction accuracy of the external characteristics of the water jet propulsion pump can be effectively improved by correcting these three highly sensitive parameters, and the correction values of the three key parameters are obtained. The prediction error of the external characteristics of the water jet propulsion pump is reduced from 4.3% to less than 2.1%. A feedforward neural network is used to establish a mapping model between the three turbulence model parameters and the head coefficient and power coefficient of the waterjet propulsion pump in order to achieve rapid prediction. The genetic algorithm is applied to optimize the weights, thresholds and other coefficients in the neural network, thereby improving the prediction accuracy. Based on the optimized neural network, the genetic algorithm is used to optimize the three turbulence model parameters, and the optimized coefficients are obtained. The optimized turbulence model parameters are put into the hydrodynamic model for RANS simulation to verify the degree of optimization of the model coefficients by the genetic algorithm.
Influence of the number of guide vane blades on the energy conversion characteristics of gas-liquid mixing pumps
Authors: Li Rennian , Pan Ranchen , Han Wei , Yang Yubin , Zhao Longlong
Published: October 2024

To investigate the optimal number of guide vanes for peak performance efficiency in a mixing pump, this study employs a self-engineered gas-liquid mixing pump to the principal subject of analysis. adopts SST κ -ω turbulence model, Euler multiphase flow model and SIMPLEC algorithm, and conducts three-dimensional flow field numerical simulation under five operating conditions with the number of guide vane of the gas-liquid mixing pump as 5, 7, 9, 11, 13, 15, and 17, and the volume gas content as 10% to 50%, respectively. Volume gas content were 10% ∼ 50% of the five conditions for three-dimensional flow field numerical simulation, the experimental findings indicate that: with an increase in the number of guide vane blades, the efficiency of the pump’s secondary impeller varies in a cubic function relationship. When the gas content at the inlet is between 10% and 20%, efficiency is highest with 9 blades. When the gas content at the inlet is between 30% and 50%, efficiency is highest with 15 blades. Additionally, when there are 9 blades, the head of the secondary impeller reaches its maximum at different gas contents at the inlet.
Study on flow characteristics and structural properties of vertical axial pump with low guide vane height
Authors: Zhao Heng , Cheng Li
Published: October 2024

With the full construction of the South to North Water Diversion Project and the renovation of pumping stations, vertical axial flow pump devices have been widely used in various pumping station projects. This article uses the streamlined method to design the impeller and guide vanes of a vertical axial flow pump device. To analyze the hydraulic and structural characteristics, this paper uses CFD numerical simulation and fluid-structure interaction calculation methods. And the trend of output power change under different flow conditions was divided into three stages, elucidating the reasons for the sudden change in output power under flow conditions of 0.8Q-1.0Q. This article focuses on analyzing the internal flow state of the designed lower height guide vane segment to explore the problem of low guide vane height that is prone to occur during the design process. According to the research results, it is found that the lower height guide vane can also play a good role in stabilizing flow and recovering circulation under certain operating conditions. This article also studied the structural characteristics of the impeller and guide vanes, explaining the stress and strain distribution under design flow conditions.
CFD analyses and model tests for the optimization design of a large mixed-flow pumping system
Authors: Liu Xueqin , Zhu Feng , Zhang Juan , Zhang Rentian , Zhu Honggeng
Published: October 2024

Aiming at the optimization design of the pumping system with mixed-flow pumps, a serial of comparative hydraulic tests, numerical simulation and physical model tests were carried out. The comparative hydraulic test results of suction and discharge passages showed that the design scheme proposed by authors had better flow patterns and smaller hydraulic loss. The comparative CFD analyses indicated that the internal flow in the elbow-type suction box designed by authors were smoother and the flow conditions generated for pump were slightly better, but the flow distribution on both sides of partition pier in the siphon-type discharge passage was obvious poor compared with the scheme proposed by the contractor. Model tests were carried out respectively in the overseas and domestic and the model test results were basically consistent with those of numerical prediction, but the pumping system efficiency in high efficiency zone achieved in model tests was a litter lower than that by CFD. The optimized pumping system was characteristic of higher pumping efficiency and larger flow rate when operated at the designed conditions. The measuring results onsite shown that the best efficiency is more than 80% by use of the optimized pumping system installing mixed-flow pumps with guide vanes.
Numerical analysis of pressure fluctuations in hump region of a pump-turbine
Authors: Liang Ao , Li Huichuang , Yang Jiahang , Hu Liwei , Zhang Wenwu
Published: October 2024

To reveal the pressure fluctuation characteristics in hump region of a pump-turbine, unsteady simulation for the whole flow passage, based on the SST k-w model, was performed on a pump-turbine model. This study analyzed the time-frequency characteristics and variation laws of pressure fluctuations in different flow passage components, and explored the relationship between pressure fluctuations and internal flow in the vaneless space, guide vane and draft tube. The results indicate that pressure fluctuations in the vaneless space primarily include the blade passing frequency of 7fn and its harmonics, and a low-frequency component of 0.15fn caused by rotating stall. Particularly, rotating stall has the greatest impact on pressure fluctuations in the guide vane. As the flow rates decreased, flow separation intensified and pressure fluctuations increased gradually. The frequencies of pressure fluctuations in the runner include runner rotation frequency of fn and its harmonics, rotor-stator interaction frequency of 20fn, and others related to internal vortices (1.45fn and 2.9fn). In the guide vane, spiral casing, and draft tube, the dominant frequencies were low-frequency components of 0.15fn and 0.1fn, and its amplitude in the spiral casing and draft tube was approximately 5% and 10% of that in the guide vane.
Analysis of the influence of different support types on the operation performance of bidirectional shaft tubular pump
Authors: Zhang Juan , Chen Hongcheng , Zhang Peng , Xu Liping , Wang Keliang , Jin Yan
Published: October 2024

Because of the particularity of the pump’s bidirectional operation, and the difference of the flow channels on both sides of the pump. The device has a mature impeller and guide vane combination when it is running forward. And when the device runs in reverse, the support on the shaft side acts as the rear guide vane of the impeller, which has great influence on the performance of the device. However, due to the few operating conditions in reverse operation, the importance of support is often ignored. In this paper, the influence of different support types on the bidirectional flow pattern and performance of the device is analyzed by numerical simulation. The results indicate that by optimizing the variation trend of the edge arc radius of the supporting baffle section, it is possible to effectively control the section with poor flow distribution, thereby reducing hydraulic losses. The support adopts three partitions arranged at an interval of 120°, which has little difference in performance during forward operation compared with other schemes. But during reverse operation, it reduces the impact and friction losses of water flow. And it fully utilizes the direct guide vane function of recovering vorticity, resulting in a significant increase in efficiency. At the same time, the accuracy of numerical simulation results is verified by model tests. The stability of positive and negative operating pressure pulsation supporting the inlet and outlet under the optimal scheme is analyzed.
Study on the transient cavitation characteristics in an axial flow tandem pump during the rapid starting period
Authors: Huang Jun , Zheng Fengchuan , Wang Yuhu , Chen Tairan , Wang Yana
Published: October 2024

In axial flow pump systems constrained by limited internal space, the advantages of axial flow tandem pumps are high space utilization, strong power capacity, and great thrust. The onset of cavitation during the rapid starting period poses a classic issue for tandem axial flow pumps, resulting in issues like noise, vibration, cavitation breakdown, and material damage. This article aims to investigate the transient cavitation characteristics of each flow passage component of an axial flow tandem pump during the rapid starting period by numerical simulation method. It is compared that the evolution laws of the cavity of each flow passage component. The evolution of the cavity in all flow passage components is strongly correlated with the flow rate change rate in each stage of the rapid starting period. Among all flow passage components, the first impeller firstly experiences cavitation, and its cavitation severity is also the most severe. The Effective Net Positive Suction Head (NPSHa
) can reduce the influence of transient effects on cavity prediction and better characterize the details of the cavity evolution in different impellers than the cavitation number σ during the rapid starting period. Meanwhile, The NPSHa
of the second impeller inlet is always higher than that of the first impeller inlet, indicating superior cavitation performance for the second impeller.
Study on the impact of turbulent spatiotemporal propagation in the outlet passage on the performance of vertical axial flow pumps.
Authors: Chen Bingning , Jin Yan , Song Xijie , Zhang Ye , Ni Debin
Published: October 2024

Pumping station engineering is crucial for our country’s national economy as a part of water conservancy infrastructure. The vertical axial flow pump commonly used in pumping station construction features a high flow rate and low discharge pressure. Understanding the impact of turbulence on the flow of water entering and leaving the pump unit is crucial for the efficient and reliable operation of a pumping station. This paper examines the internal flow and hydraulic characteristics of the device for vertical axial flow pump at a pumping station through numerical simulation technology and experimental validation. It is inferred that turbulent flow develops in the outlet flow passage while the pump device is currently functioning, impacting the impeller’s outlet bend and guide vane. This leads to the formation of vortices, backflow, and folding flow at the guide vane and outlet bend. As water flows out through the outlet passage, bias and backflow develop, causing erosion on both sides of the outlet pool and impacting the pump unit’s overall head and efficiency.
Influence of axial distance between impeller and diffuser on the hydraulic performance and flow loss characteristics of bulb tubular pump
Authors: Wu Jinxin , Pan Weifeng , Cheng Li
Published: October 2024

Bulb tubular pumps used in regional water transfer projects consume substantial power. Optimizing the geometric parameters of tubular pumps is crucial for enhancing efficiency and minimizing hydraulic losses. ANSYS CFX is used to investigate the axial distance between the impeller and the diffuser on the hydraulic performance and flow loss characteristics of the rear-bulb tubular pump, and the numerical simulation results are compared with the experimental data. Then, the entropy production theory is introduced to analyze flow losses. As the axial distance increases, the diffuser’s rectification effect on the flow at the impeller outlet deteriorates, leading to increased flow losses and decreased head and efficiency of the device. Flow losses in the bulb tubular pump are ranked from largest to smallest as follows: impeller, outflow channel, diffuser, inlet channel. The impeller exhibits the highest entropy production ratio, reaching 61.05% at an axial distance of 25 mm. By elucidating the energy loss distribution of each component under varying axial distances, this paper offers insights for the hydraulic optimization design of bulb tubular pumps.
Experimental study on energy and hydraulic performance of the axial flow pumping device with bell-shaped inlet channel
Authors: Shen Fangfang , Xu Xudong , Zhang Hui , Li Wei , Tang Yu
Published: October 2024

Due to the unique inlet design of the axial flow pump device with a bell shaped inlet channel, there is currently insufficient quantitative research on its hydraulic characteristics. This study investigates the hydraulic behavior of a vertical axial flow pumping device equipped with a bell-shaped inlet channel, analyzing various blade angles. Energy, cavitation, runaway, and pressure pulsation characteristics were assessed through meticulous testing on a high-precision test bench. Experimental findings indicate that altering the blade angle of the vertical axial flow pumping device with a bell-shaped inlet channel can influence its overall efficiency to some extent. Moreover, as the pump’s blade angle increases incrementally, the device’s cavitation performance gradually diminishes. Pressure pulsation tests reveal a relatively minor amplitude of pressure pulsation at the impeller outlet, contrasting with a more pronounced amplitude observed at the guide vane outlet compared to the pump outlet. These research results provide valuable insights for the design and optimization of actual pumping stations.
Evaluation of Clogging Potential Prediction Methods in Axial Flow Waterjet Pumps with CFD-DEM
Authors: Minetoma Yuki , Kondo Yuki , Miyagawa Kazuyoshi , Sano Takeshi , Suematsu Junichi
Published: October 2024

Axial flow waterjet pumps propel high-speed passenger vessels by energizing and expelling fluid. In operation, foreign objects may enter, especially in shallow waters, potentially leading to performance decline and damage. Evaluating passage performance is crucial but primarily experimental and computationally costly. Limited research exists on deliberately introducing solids into axial flow pumps due to visualization challenges. Hence, experiments simulated solid substance entry into axial flow pumps, varying particle conditions. High-speed cameras visualized particle behaviour, exploring retention and optimal pump shapes. Additionally, simulations using the Discrete Element Method (DEM) confirmed its utility in predicting foreign object passage, with variations in particle retention across regions noted.
Investigation into the Energy Loss Mechanism of Pump Turbine During the Runaway Process Based on Entropy Production Theory
Authors: Li Yanyan , Guo Pengcheng , Cao Mengjia , Sun Longgang
Published: October 2024

The power-trip of the pump under certain conditions leads to the runaway of the unit, causing dangerous transitional process in pumped storage power stations. This process is characterized by transient hydraulic features like flow separation and vortex structures, which increase hydraulic losses significantly and severely impact unit efficiency and stability. This paper aims to elucidate the mechanism of energy loss due to unstable flow during pump turbine runaway. It focuses on a high-head model pump turbine, examining the transient flow process from pump conditions to runaway conditions. It conducts quantitative analysis of energy loss using entropy production theory, besides, further clarifies the location and causes of hydraulic losses by integrating with internal flow analysis. The results show that a significant high-entropy production zone is captured in the pump braking condition, indicating extremely chaotic internal flow in this area during the runaway transition process. Additionally, throughout the transition process, turbulent entropy production initially increases, then decreases. Turbulent entropy production accounts for more than 80% of total entropy production, indicating that turbulent entropy production dominates throughout the entire transition process. The energy of the water is primarily dissipated within the runner during the runaway process. The maximum proportion is 87%, which is in the pump braking condition. Correlation analysis between flow and hydraulic losses reveals that vortex structure induced by flow separation under off-design conditions is the primary contributor to increased hydraulic losses.
Research on the Internal Flow Characteristics of an Electric Coolant Pump
Authors: Yang Zhengyin , Yang Anlong , Gu Yandong , Zhang Lin , Zhu Dongdong , Zhou Zhiqiang , Ouyang Xili
Published: October 2024

To investigate the internal flow characteristics of an automotive electronic coolant pump, numerical simulations were performed utilizing the ANSYS CFX commercial software suite. The study delved into the velocity distribution, pressure pulsation intensity characteristics, and entropy generation of the electronic coolant pump under varying operational conditions. The findings revealed that with an increase in the flow rate, the coolant flow velocity within the pump also escalated. Concurrently, the separation flow at the trailing edge of the blade diminished, while the flow velocity at the trailing edge of the pressure surface escalated. Notably, the impeller and volute emerged as the primary sites generating pressure pulsations, with pressure pulsation intensity within the pump surpassing that of the design condition in off-design scenarios. Furthermore, entropy generation predominantly manifested at the impeller, volute, and front pump chamber locations, with the impeller exhibiting minimal total entropy generation under design conditions. These insights serve as crucial reference points for optimizing the design of automotive electronic coolant pumps.
Study on the internal flow evolution mechanism and pressure pulsation characteristics of the transient process of variable speed regulation of centrifugal pump
Authors: Li Zhi , Dong Wei , Zhou Chenyu , Li Peixuan , Zhang Haichen
Published: October 2024

In view of the fact that it is not possible to quantitatively analyze any change in the internal flow characteristics of traditional centrifugal pumps during variable speed regulation, numerical computational fluid dynamics (CFD) simulations were carried out in this study to obtain the optimal adjustment range of variable speed regulation. A single-stage IS80-65-160 centrifugal pump is modeled in 3D using Pro/E and ICEM software, followed by CFD simulations. Results are compared with experimental data, showing good agreement. Variable speed adjustments ranging from 0.5-1.0 times the original values are applied to observe changes in internal flow characteristics, such as velocity and turbulent kinetic energy. Pressure and velocity variations in different parts of the pump are studied under varied working conditions. Pressure pulsation frequency domain characteristics are measured at monitoring points in the volute. Findings indicate that as flow rate decreases due to variable speed regulation, velocity decreases linearly, while turbulent kinetic energy decreases quadratically in a uniform distribution. Pressure fluctuations within the volute remain within 0.01 Cp range, but at the tongue, fluctuations can reach up to 0.6 Cp, suggesting an optimal adjustment range within 30% of the rated value.
Visualization experiment of solid-liquid two-phase flow transportation in a jet pump
Authors: Chuanhao Fan , Mengxue Dong , Maosen Xu , Jiegang Mou , Pengfei Han
Published: October 2024

Due to its lack of internal moving components, the jet pump offers widespread application possibilities in solid-liquid two-phase flow transportation. Utilizing high-speed photography, this research established a visual experimental platform for jet pumps, allowing for a detailed study and analysis of the dynamics of solid particles entering, mixing, and being conveyed through the jet pump. The following results were obtained. The introduction of solid phase particles into the jet pump results in decreased pressure ratio and efficiency, yet the general trajectory of change within the pump system remains constant. With decreasing particle size, particles become increasingly susceptible to being entrained and propelled into the jet pump by the high-velocity jet flow. The proportion of particle distribution in the mixing chamber rises as the flow ratio goes up. However, when the flow ratio falls below 0.6, the changes in particle distribution beneath the jet zone of the mixing chamber become insignificant, primarily due to the impact of particle deposition within the suction chamber. A reflux zone is observed in the throat, which gradually shrinks in length as the flow ratio increases.
Applicability of extended vortex identification methods for two-phase separation in multiphase pump
Authors: Wu Xitong , Li Chenhao , Luo Xingqi , Feng Jianjun , Zhu Guojun
Published: October 2024

In the process of multiphase flow transport, there is a slip velocity between phases, which affects the interphase force and leads to the separation of two phases. In order to analyze the flow structure of phases separation motion, the extended vortex identification methods in a multiphase pump is evaluated. The results show that the generation of two-phase separation structure inside the fluid machinery will seriously affect the phase distribution characteristics of the fluid machinery, and then affect the internal flow field and external performance. The extended vortex identification methods can characterize the intensity, location and evolution of two-phase separation in the pump. The research can offer a pertinent theoretical foundation for subsequent flow analysis and design optimization.
Research on the internal flow characteristics of centrifugal pump based on streamlined anti-guide vane
Authors: Ma Jinshui , Li Chenhao , Li Lu , Luo Xingqi , Zhu Guojun
Published: October 2024

Anti-guide vane is part of the radial guide vane in multi-stage centrifugal pump, and the hydraulic loss of anti-guide vane is the dominant factor affecting the performance of radial guide vane. In this paper, the radial guide vane is chosen as the research object, an optimization scheme of streamlined anti-guide vane is proposed based on the arc-shaped anti-guide vane with inlet angle α=25°. The simulation calculation of multi-stage centrifugal pump is drawn using the SST k-ω turbulence model. and the influence of the streamlined anti-guide vane on the hydraulic performance is studied. The result shows that: Under various flow conditions, the head of the multistage centrifugal pump with streamlined anti-guide vanes is higher than that of the prototype. When the flow rate is 1.3Q, the head is increased by 7.2%. and the efficiency is increased by 2.3%. The amplitude of pressure fluctuation of the streamlined anti-guide vane is significantly decreased at each monitoring point compared to the prototype, indicating that the streamlined anti-guide vane weakens the influence of the pressure fluctuation. Furthermore, the streamlined anti-guide vane enhances the pre-swirl of the inlet fluid to the secondary impeller, reduces the impact loss, and improves the pressurization capacity of the secondary impeller.
Optimization of geometrical parameters of positive guide vane for multi-stage pump as turbine based on orthogonal test
Authors: Wang Shicheng , Yang Junhu , Xu Guobin
Published: October 2024

Multi-stage pumps as turbines (PAT) are commonly employed in the petrochemical, coal chemical, and other process industries to recover liquid residual pressure energy. This study focused on improving the performance of multi-stage PAT, specifically targeting the slope of the power-flow(P-Q) curve and hydraulic efficiency at the rated flow point. A two-stage PAT was selected as the research object for this study. According to the relationship between the power and the geometrical parameters of the positive guide vane derived based on the basic equation of the multi-stage PAT, four parameters of the positive guide vane were selected as the test factors for the orthogonal experimental study. A four-factor, three-level orthogonal table of type L9(34) was established. Using Fluent software and the RNG k-ε turbulence model to carry out numerical calculations of constant flow, the results showed that: for the slope of the P-Q curve, the influence of geometric parameter factors of the positive guide vane are in the order of the throat area, the outlet placement angle, the positive guide vanes number, and the base circle diameter; and for the hydraulic efficiency, the influence of geometric parameter factors of the positive guide vane are in the order of the throat area, the positive guide vanes number, the outlet placement angle, and the base circle diameter of the positive guide vane. At the rated flow point, the P-Q curve of the optimized solution decreased by 0.24, resulting in a flatter curve and a 0.3% increase in hydraulic efficiency. There was little change in the vicinity at the rated flow point. The best efficiency point of the optimized scheme is biased toward the high flow rate, the efficiency is increased by 1.85%, and the best efficiency zone is wider. Therefore, selecting appropriate positive guide vane geometry parameters can flatten the P-Q curve, improve internal flow, and enhance hydraulic efficiency.
Analysis of variable speed operating range of centrifugal pump with large flow and wide head variation
Authors: Zheng Yang , Tian Yajuan , Zhang Chiye , Wang Xin , Meng Long
Published: October 2024

The advantages of variable speed centrifugal pump include its broad operating range, wide operating efficiency zone, high operational stability, and regulative characteristics of input power. When pump station has characteristics such as large flow rate changes, large pump head changes, the conventional fixed speed centrifugal pump cannot meet requirements of safe and stable operation under characteristic pump conditions. In order to ensure the safe and stable operation of the pump station within the operation range, the variable speed operation strategy of centrifugal pumps is adopted to enhance its wide amplitude adjustment capability and efficient operation. This paper uses an 8MW centrifugal pump with wide head range in China to analyze the factors that influence the operating range of pump unit in detail. The results indicate that the variable speed pump unit’s safe and effective operating range is determined by the cavitation margin, hump margin, speed range, and pump maximum input power. The hydraulic design can improve the hump safety margin and cavitation characteristics of the operating zone, and then expand the operating range of the pump unit. Meanwhile, increasing the static suction head, reducing the hump margin, controlling pump head amplitude, and appropriately increasing the maximum input power limit are the best ways to extend centrifugal pump’s operating range and improve its adjustable capability. The results can provide reference for parameter selection and hydraulic design of large variable centrifugal pump in the future.
An Improved Grey Wolf Optimizer(IGWO) algorithm for optimization of centrifugal pump with guide vane
Authors: Jian Dong , Jinling Lu , Wuke Liang , Wei Wang , Gaigai Ai
Published: October 2024

To improve the hydraulic performance of a centrifugal pump with guide vane, an improved grey wolf optimizer (IGWO) algorithm is proposed. First, the IGWO algorithm enhances the diversity and global exploration of the initial population with optimal Latin hypercube sampling. Then, the convergence factor is improved by combining the Tanh function to meet the needs of complex non-linear optimization problems. Finally, a search mechanism that enhances population communication is constructed and combined with a mutation-driven search scheme to improve the ability to avoids the local optima traps. The results show that IGWO algorithm has obvious advantages in convergence speed and robustness when dealing with complex non-linear optimization problems. Additionally, satisfactory results are achieved in the application of centrifugal pump optimization. The efficiency of optimized pump reaches 87.8%, which is 1.2% higher than that of the original pump. The anti-cavitation performance of the centrifugal pump is enhanced by improving the distribution of blade inlet attack angles. The vortex area inside the optimized pump impeller is reduced over a large area, and the operating stability of the pump, the matching between the impeller and the guide vane, and the flow characteristics in the guide vane domain are all improved.
Study on the influence of guide vane opening on pressure pulsation of pump-turbine under zero flow pump condition
Authors: Yi Chuanbao , Lu Yonggang , Li Xiji , Zhao Yun , Sun Chuanzhen , Wang Zhengwei
Published: October 2024

Reversible pump-turbine is the key equipment of energy conversion in large pumped storage power station, and it is the core of stable operation of power station. Under the pump condition, the internal pressure pulsation law of the pump-turbine has an important influence on the stable operation of the pump. In order to study the pressure pulsation characteristics of pump-turbine in pump mode under zero flow condition, this study carried out unsteady numerical simulation on three kinds of guide vane openings, and analyzed the amplitude frequency characteristics of pressure pulsation in turbine under different head and the influence of internal flow characteristics on pressure pulsation. The research shows that in the pump mode, when the guide vane opening of the turbine increases, the influence of the blade frequency and the shaft frequency on the vaneless area increases, resulting in the maximum pressure fluctuation amplitude in the vaneless area under the pump condition, especially when GVO = 19 °. At the same time, due to the influence of dynamic and static interference, the larger turbulent kinetic energy appears in the vaneless area and the connection between the guide vane flow channel and the runner flow channel, resulting in an increase in hydraulic loss. Both the experimental and simulation results show that the guide vane opening of 19 ° should be avoided to reduce the hydraulic loss in the vaneless area when the turbine is operated under the zero flow pump condition.
Optimization Design of Bionic Leading-edge Protuberances on Horizontal Axis Wind Turbine Blades
Authors: Wei X T , Li D Y , Zhang R Y , Chang H , Wang H J
Published: October 2024

The complex operating environments of horizontal axis wind turbines has made the phenomenon of blade flow separation more obvious. As a passive flow control method, the bionic humpback whale leading-edge protuberances have been shown to effectively enhance the performance of the wind turbine. This study employs a multi-objective genetic algorithm and Computational Fluid Dynamics method to analyse the impact of leading-edge protuberances on the aerodynamic performance and flow characteristics of the blades. The results indicate a significant improvement in blade performance after optimization in the wind turbine’s output power. The streamwise vortices generated by the bionic protuberances not only reduce the suction surface pressure, but also suppress the spanwise flow over the blade surface. The length of the flow separation Region is reduced from 0.410 to 0.368 radius. In the process of wind speed change, the tangential forces on the bionic blade exhibit a wave-like variation. The bionic protuberance alters the pressure coefficient of the position. Compared with the original blade, the pressure coefficient of the trough sections on both sides of the bionic blade protuberance is improved. In this study, the bionic protuberance applied to the leading-edge of horizontal-axis wind turbine blades is proposed for the first time, and holds practical value for guiding practical applications.
Aerodynamic design and optimization analysis of a 200 kW radial-inflow turbine
Authors: Wan Bochen , Zheng Wang , Zhang Zhen , Si Qiaorui
Published: October 2024

In low-temperature waste heat recovery for organic Rankine cycle (ORC) power generation, the radial-inflow turbine (RIT) plays a crucial role. This study focuses on the preliminary design, three-dimensional simulations, and optimization of a 200 kW RIT for R245fa working fluid. The turbine’s preliminary design relies on selected empirical coefficients, leading to performance uncertainty. The performance of the turbine obtained from the initial design was evaluated using computer simulations, indicating that achieving outstanding isentropic efficiency and power targets solely relying on the design of empirical coefficients can sometimes be challenging. Design of Experiments (DOE) on five variables was performed using the Isight platform, highlighting rotor inlet blade height as crucial for turbine performance. The optimized RIT showed a 10.5% efficiency increase and 45.6 kW power gain. Entropy production analysis confirmed substantial improvement. Systematic theoretical calculations followed by DOE optimization effectively enhance turbine efficiency, providing valuable and innovative insights for satisfactory design solutions.
Analysis of safety margin for pump-turbine “S” characteristics of Pumped-storage Power Stations
Authors: Xiao Wei , Liu Dianhai
Published: October 2024

The pump-turbine is the “heart” of Pumped-storage Power Stations, and the “S” characteristics is an inherent characteristic of the routine Francis pump-turbine unit, which is an important factor affecting the safe and stable operation of the unit. There are three main methods for conducting research on the “S” characteristics: model testing, on-site testing, and CFD numerical simulation calculation. Based on the theoretical research of CFD numerical simulation calculation, this article compares and analyzes the results of model testing and on-site testing for specific practical cases, studies the differences between these two methods, and provides suggestions for the reasonable value of safety margin in the “S” area of the pump-turbine based on engineering practice, providing reference for the design of new or renovated power stations and the hydraulic optimization of pump-turbines.
Investigation on the hydraulic loss in the vertical inlet and outlet of a pumped storage power station
Authors: Guo Miao , Wang Zhiheng , Song Ruixiang , Xu Guibin , Wang Wei , Shen Yan
Published: October 2024

The vertical inlet/outlet is commonly adopted in the upper reservoir of pumped-storage power stations, in which the internal flow patterns exert a critical influence on the safety and operational efficiency of the entire power station. Based on the standard k-ε turbulence model coupled with the revised wall roughness theory, this investigation presented a numerical model of a vertical inlet/outlet in a pumped-storage upper reservoir and the validity and accuracy of the numerical simulation are validated through comparison well with the results of the model experiments. The results suggest that the emergence of vortices of varying intensities near the inlet during power-generation scenarios at dead water levels and at 3.5 times of the rated flow rate (389.6 m3/s). The bend section experiences fairly nonuniform flow velocity, with the highest average flow hydraulic loss in the entire vertical pipe inlet/outlet system. These insights provide a substantial utility for operational strategies and optimization designs in related engineering projects.
Design and Performance study of Francis turbine for high head applications.
Authors: Shrestha Kushal , Bijukchhe Pawan Lal , Neopane Hari Prasad , Chitrakar Sailesh , Thapa Bhola
Published: October 2024

Francis Turbines are widely employed globally for their adaptability and operational versatility across a broad range of water flow rates and pressure heads. This study explores the design and optimization of a Francis turbine configured for exceptionally high heads, specifically targeting a design head of 700 m. Traditionally, Pelton turbines are favoured for such high heads, but this study investigates the viability of Francis turbines in this range. Through comprehensive testing, including the development of hill chart diagrams to evaluate performance under various conditions, the study demonstrates promising efficiency levels. Utilizing a simplified approach, the design process involves empirical relations and the Khoj program, resulting in turbine designs representing three different speed numbers: 0.32, 0.42, and 0.52. Efficiency and sediment erosion rates were computed for each and compared between the three designs. The comparison indicates that while the turbine with a speed number of 0.32 exhibits lower efficiency, it offers superior erosion resistivity. Conversely, turbines with speed numbers 0.42 or 0.52 show better efficiency, especially in handling fluctuations in operating conditions. The findings suggest a balance between efficiency and erosion resistivity, recommending the turbine designed for a speed number of 0.32 for superior erosion resistance, and the turbine with a speed number of 0.42 for greater efficiency and operational range. This study broadens the horizon for Francis turbines in high-head applications, offering insights into their potential and viability in extreme conditions.
Research on Optimal Control Strategy for Hydroelectric Units Based on Generalized Smith Predictor and Shortest Time Control
Authors: Qi Guoyang , Luo Xingqi , Men Chuangshe , Li Chenhao
Published: October 2024

At present, most hydroelectric unit controllers use PID speed controllers. The principle of PID control is simple and the technology is mature, but there is less consideration for the need for deep participation of the unit in power grid regulation, resulting in a decrease in regulation quality and even instability of the regulation process when the unit deviates from the design operating conditions, which is difficult to meet the requirements of fast response and high-precision operation of the unit in the new power grid. This article proposes a new control strategy based on the generalized Smith predictor and the shortest time control. Through simulation comparison of the dynamic characteristics of the new control strategy and the conventional PID controller, the results show that the proposed new control strategy has better dynamic characteristics and control accuracy.
Study on the dynamic characteristics of the head cover-bolts-stay ring of a variable-speed pump-turbine
Authors: Yu Shuang , Wang Lei , Wang Zhengwei , Ding Sen
Published: October 2024

The design and operation of variable-speed pump-turbine units is more difficult than that of conventional units due to their adjustable speed, frequent start stop, and forward and reverse operation. Due to the development of variable-speed pump-turbines towards variable-speed, high head, and large capacity, the vibration instability caused by frequent switching between turbine and pump operating conditions is more prominent. The study on the dynamic characteristics of the head cover-bolts-stay ring system is an important guarantee for the long-term safe and stable operation of the units. This article uses the finite element method to conduct modal analysis on the head cover-bolts-stay ring system of a variable-speed pump-turbine. The natural frequency and mode shape are analyzed, and resonance analysis is carried out in combination with the dynamic and static interference characteristics of the variable-speed unit. The research results show that the dynamic and static interference frequency of the unit during the variable-speed process may be close to the natural frequency of the head cover-bolts-stay ring system, which needs to be paid attention to during operation. The results and findings in this article provide theory and practical basis for the research and design of high head, large capacity, and variable-speed pump-turbine units.
Study on the dynamic response behaviour of the head cover-bolts-stay ring of a variable-speed pump-turbine
Authors: Wang Lei , Wang Zhengwei , Yang Shengrui , Yu Shuang , Wei Zichao
Published: October 2024

The vibration characteristics of the hydro-turbine’s head cover is a significant factor that affects the safety of the unit. This paper established the Finite Element Method (FEM) model for the head cover-bolts-stay ring system of a variable-speed pump-turbine, and the dynamic response behaviour of the system under pretension and hydraulic excitation conditions is analyzed. The results indicate that the maximum value of stress locates at the bolt root, which is 715.6MPa under pretension load and 678.7MPa under hydraulic excitation. The results presented in this paper offer valuable guidance for the safety and stability of the variable-speed pump-turbine.
Research on the clearance evolution of preloading filling spiral case and surrounding concrete
Authors: Lu Zhaohui , Luo Yutong , Zhang Zhenwei , Wang Zhengwei
Published: October 2024

The embedment of steel spiral cases within concrete under a pressurized condition is a kind of construction approach that widely used in pump-turbines. There will be an initial preloading clearance between the spiral case and surrounding concrete after the construction. The clearance is directly determined by the preloading water head and changes with the variation in operational hydraulic pressure, which will effect the combined load transmission mechanism. This paper investigates the clearance evolution of preloading filling spiral cases and surrounding concrete under different internal pressure. The effect of the preloading water head on the initial clearance, the contact characteristics and the combined load transmission mechanism under different internal pressure are numerically studied. The results show that the initial clearance between the spiral case and concrete increases with the rise of the preloading water head. The maximum clearances are all located at the waist of the spiral case. The clearance during operation presents uneven distribution characteristics in spatial and temporal scales. Before the internal water pressure comes to the preloading water head, the inlet, outer part in the direction of 45° and the sectional area are the first to close, the outer part of the waist follows, while the outer area of the spiral case middle remains open when the pressure reaches the preloading water head. The contact pressure distribution is consistent with the contact status characteristic. The conclusion of this paper aims to improve the understanding of the effect of the clearance between the preloading filling spiral case and concrete, so as to provide theoretical reference for safe and stable operation of pump-turbine units.