bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence factors of clearance leakage flowrate and clearance hydraulic axial force of pump-turbine
Authors: Hou X X , Cheng Y G , Hu D L , Xue S , Wang B , Zhang X X , Wang X , Ding J H , Liu D M 
Published: June 2022

Abstract
The clearance flow of pump-turbine has significant influence on hydraulic forces of the runner, which is related to safety of the unit. To clarify the influence factors, clearance flowrate and clearance hydraulic axial force of a prototype pump-turbine were analyzed by 3D CFD simulations. The results show that the rotational speed, and the smallest radial sizes of clearance inlet, outlet, and the seal ring sizes are the determinant factors for clearance leakage flowrate, while the rotational speed and the radial size at clearance inlet are the major factors for clearance axial force. The rotational speed of rotating surfaces mainly affects the strength of rotating shear flow, while geometric sizes mainly affect the hydraulic loss of leakage flow. By assuming that the clearance region as several ring pipes, we obtained the simplified calculation formulas for estimating clearance leakage flowrate and clearance axial force. The flowrate can be expressed as a function of the water head difference across the clearance region, the rotational speed, and the sizes of clearance inlet, outlet and sealing ring, while the clearance axial force is a function of the inlet pressure and the square of both radius and rotational speed. The formula calculations agree with the numerical simulations well. This paper can provide a reference for runner clearance size design.
Numerical Investigation on Hydraulic Performance at Low Flow Rates of a Mixed-flow Pump with Impeller Inlet Diameter Effects
Authors: Kim Y I , Yang H M , Lee K Y , Choi Y S 
Published: June 2022

Abstract
A mixed-flow pump has a characteristic in which the pressure (P) decreases as the flow rate (Q) increases on the performance curve. Hence, the Q-P curve generally has a negative slope, which has been understood as an ideal and stable case. However, a complex recirculating flow may occur due to the increase in incidence angle at the low flow rates compared to the design flow rate. This phenomenon accompanies noise and vibration along with the deterioration of performance and causes a positive slope in the form of a saddle on the performance curve. In this study, the effect of the impeller inlet (eye) diameter of a mixed-flow pump on the saddle characteristics was confirmed through numerical simulation. The focus was on the internal flow field and performance of a pump, which could be solved with the steady-state analysis. Here, the impeller inlet diameter was adjusted with the leading edge (LE) vertex on the shroud line of the meridional plane. The blade angle was adjusted accordingly to maintain the previously optimized degree of the incidence angle. From this novel design method, the saddle characteristics were significantly improved. The performance in the saddle range was directly related to the recirculating flow near the shroud. The numerical results were validated with the experimental tests.
Numerical investigation of the non-condensable gas effect on predicting the cavitation performance of a centrifugal pump
Authors: Cao Lei , Mingming Liu , Zhengwei Wang , Yiyang Zhang 
Published: June 2022

Abstract
Improving the prediction accuracy of cavitation performance of pumps is a research hotspot. The non-condensable gas effect has been included in some existing cavitation models. However, the amount of the non-condensable gas in water still needs discussing since it will affect the vaporization process. In this paper, Zwart-Gerber-Belamri model was used to calculate the cavitation performance of a three-blade centrifugal pump with water temperature of 10 °C and a corresponding cavitation experiment was carried out to verify the numerical model. Numerical results respectively with five volume fractions of the non-condensable gas were analyzed. Compared to the recommended default value, the head drop curve obtained with a much lower volume fraction of the non-condensable gas agrees better with the experimental result. Comparison and analysis of the cavitation patterns as well as the flow field indicates that the default volume fraction of the non-condensable gas which was proposed at 25 °C overestimates the interphase mass transfer rate at 10 °C Reasonably setting the volume fraction of non-condensable gas in the cavitation model will achieve more accurate cavitation pattern, and then the head drop curve of pump can be predicted more precisely.
Study on Measurement of Penstock Head Loss for Hydropower Station with Multiple Units Per Penstock
Authors: Zhou Y , Tuo Y , Cao D F , Li C L , Wu D J 
Published: June 2022

Abstract
For a hydropower station with multiple units per penstock, how to get the head loss of penstock has usually been a difficult problem, which the core issue is that it is hard to obtain the flow of each branch pipe. For power stations that have installed flow measurement devices for all units, or have undergone absolute turbine efficiency tests, the head measurement is relatively simple, but if the flow measuring device is not installed for each unit in advance, the head loss measurement will be difficult. This paper proposes an optimized measurement method performed in a hydropower station in Pakistan, which is to arrange an ultrasonic flowmeter on the main penstock, and then use the Winter-Kennedy method and flow rate measured by Ultrasonic flow meter to calibrate the Winter-Kennedy coefficients of unit one by one. Finally, by running three units at the same time and adjusting them with the same flow rate, the total loss of the penstock is calculated. At the same time, the flow rate measured by the Winter-Kennedy coefficient and that measured by the ultrasonic method has been checked and compared. The result proves that the accuracy of the result is high, and the result has a good consistency, which can fully meet the requirements of penstock head loss calculation and evaluation. The method has a certain practical value and can be referred to by other power station which has similar measurement.
Unsteady Simulation of the Internal Flow in a Tubular Pump Considering Tip-Leakage Flow
Authors: Li P , Jin F , Tao R , Zhang F , Xiao R 
Published: June 2022

Abstract
Tip-leakage vortex is a commonly-seen phenomenon in tubular pump runners because there will be always gap between blade and pump shroud. In the operation process, the tip-leakage vortex is unstably varying. Pressure in the vortex core is relatively low and may induce cavitation in extreme conditions. The operation stability will be strongly impacted. As an effective tool, computational fluid dynamics (CFD) can be used in predicting the vortical flow in pumps. In this study, unsteady CFD simulation is conducted with the visualization of tip-leakage vortex using the Q criterion. The design-load condition is mainly studied. The temporal characters, their frequency domain features and their spatial distributions are fully analysed. This study will help understanding the tip-leakage vortical flow in the tubular pump and enhance the operation stability of low-head pumping stations.
Numerical simulation of the runner blade channel vortex in Francis turbine
Authors: Cheng Huan , Zhou Lingjiu , Liang Quanwei , Zhou Peijian , Wu Zhongjing , Liu Demin , Wang Zhaoning , Li Guoyuan 
Published: June 2022

Abstract
The runner blade channel vortex could induce cavitation erosion, noise and vibration, when Francis turbines operate at part load condition. It's usually difficult to simulate the channel vortex exactly in runner passage, this paper attempts to predict the runner channel vortex in some operating conditions with different discharge and speed factors.The results show that the structure and intensity of runner channel vortex are various between the vortex incipient and development line. The velocity distribution indicates that there is a relationship between the channel vortex and backflow region near the hub with different specific discharge factors, while the flow incident angle has a distinct variation with different specific speed factors. Furthermore, this work enables the researchers to understand the flow field and carry out optimization design in runner hydraulic research.
Dynamic Experimental Review of Hydraulic Turbine Stay Vane Strengthen for Baihetan Hydropower Station Left Bank
Authors: Xiaohong Fang , Haijun Li , Chunjian Cao , Jie Fang , Jinjie Deng 
Published: June 2022

Abstract
Stay ring is the foundation-bearing components of Francis turbine-generator unit and an important part of the flow components. It should not only have enough strength and rigidity, but also excellent hydraulic performance. As the unit capacity of Baihetan Hydropower Station reaches 1000MW, the priority should be on safety. After completing the turbine model acceptance test of Baihetan Hydropower Station Left Bank, it was found that the local stress at the tail of stay vanes was too high in the re-check analysis of the rigidity and strength of the stay ring. In order to ensure the stay ring has sufficient safety margin, the stay vane should be strengthened in design. After stay vane strengthened, the rigidity and strength of the stay ring are improved obviously. In this paper, the strengthen design, stiffness and strength analysis and model verification of turbine stay vane for Baihetan Hydropower Station Left Bank are analyzed and explained.
Study of the phase resonance phenomenon in Francis turbine
Authors: Lv Yue , Wang Zhengwei , Zhou Lingjiu 
Published: June 2022

Abstract
In hydraulic machinery, the phenomenon of rotor-stator interaction will produce periodic pressure waves in the stationary cascade. These pressure waves have the same phase, and will spread and superimpose in the volute. When the pressure waves propagate and superpose, the pressure pulsation with large amplitude will be formed. This phenomenon is called phase resonance, which will threaten the safe and stable operation of the machinery. Therefore, it is necessary to study the rotor-stator interference phenomenon and analyze the risk of phase resonance. In this paper, a high head Francis turbine with phase resonance in engineering is analyzed, which is also verified by the existing theoretical analysis. The phase resonance in the turbine is analyzed by using one-dimensional hydro acoustic model and three-dimensional compressible flow CFD simulation method, and the results are consistent with the actual engineering phenomenon. In order to study the measures to improve the phase resonance phenomenon, this paper carries out the simulation calculation from changing the rotation speed, wave speed and guide vane-runner blade number combination. The results show that adjusting the above parameters can reduce the amplitude of large pressure pulsation caused by the phase resonance in different degrees, and changing the number combination of guide vanes and runner blades is the most effective and feasible measure.
Vibration Analysis of 3D printed runner with CNN for using deep learning in hydropower for condition monitoring
Authors: Silwal Raman , Kafle Abishek , Shrestha Prajwal Sapkota Pratisthit Lal , Dahlhaug Dr. Ole Gunnar , Thapa Dr. Bhola 
Published: June 2022

Abstract
Convolutional Neural Networks are deep learning algorithms that are typically used for the classification of images. A black and white image can be represented as the number of rows and columns along with values of intensity for each of components of these rows and columns. Vibration measured with the help of accelerometer can be used to create an image like data. These data can be used for machine learning applications with the help of deep learning. In deep learning techniques, features do not have to be extracted from the data set. The CNN network can generate a feature-like set which can be further classified with a fully connected neural network to give out the probability over the predefined class. The neural networks model is trained with a data set created in laboratory conditions to monitor the unfractured and single blade fracture condition operation state. The paper deals with showing the proof of concept that CNN algorithms can be applied for conditional monitoring of runner blades. The paper mainly focuses on demonstrating that deep learning algorithms can be used as analysis tools for hydropower runners by applying these techniques in scaled versions of 3D printed runners.
Head-Cover vibration investigation of a Prototype Reversible Pump-Turbine Unit during Start-up in Pump mode. Part I: Fluid dynamic analysis
Authors: Yang Haixia , He Qilian , Bi Huili , Huang Xingxing , Yang Mengqi , Zou Mingde , Wang Zhengwei 
Published: June 2022

Abstract
Reversible pump-turbine units of pumped storage power stations can generate power in turbine mode and store electric energy in pump mode for load balancing of the electric power grid. During the start-up transient process in pump mode of a reversible pump-turbine, the flow pattern and the pressure distribution in the flow channel change dramatically with the increasing opening angle of guide vanes. The unsteady pressure of the flow passing channel can cause severe vibration on the head-cover, bottom ring, and other stationary structures around the impeller. In this paper, a coupled 1D/3D co-simulation approach is developed to investigate the pressure distribution characteristics of the flow field during the start-up transient process in pump mode for a large prototype reversible pump-turbine unit. The entire model of flow channel from spiral casing to draft tube is constructed and the flow characteristics of key fluid fields such as spiral casing, stay vanes, guide vanes, impeller, and draft tube are analyzed. The simulation results show that under the condition of minimum guide vane opening the flow is insufficient and vortices occur on the impeller blades. The pressure distribution results of the flow channel from 3D fluid dynamic analysis during the start-up transient process in pump mode are exported as boundary conditions for the subsequent fluid-structure coupling analysis of the head-cover vibration investigation.
Effect of fish swimming on the stability of flow fields inside the pipeline
Authors: Fang D , Huang Z , Zhang J , Hu Z 
Published: June 2022

Abstract
Hydraulic machinery and various pipeline systems will commonly be infiltrated by many aquatic creatures, and the aquatic community causes important impacts on the flow field, fluid stability inside the pipeline, and the performance of the hydraulic machinery. In this paper, the research about three-dimensional numerical simulation of fish swimming inside a pipeline is conducted, and lattice Boltzmann method is used to complete the flow field solution, where an immersed boundary method based on multi-direct forcing scheme is implemented to achieve the fluid-solid coupling. The fish swimming will be realized by using a time-dependent harmonic oscillation combined with surface vertices. The analysis of the velocity, flow field and vorticity distribution at different moments of fish swimming reveals that the fish passing through the pipeline causes a significant influence on the internal flow field, and the stability of the fluid inside the pipeline. The research in this paper provides referential significance to the operations of hydraulic machinery and pipeline systems in environments containing aquatic community.
Advanced ICT solutions in a distance vocational education and training in the field of robotics
Authors: Pilat Zbigniew , Arapi Polyxeni , Pappas Nikos , Omieljanowicz Miroslaw , Prokopiuk Norbert , Tamre Mart 
Published: June 2022

Abstract
Automation and robotization (A&R) is often the main driving force behind the development of advanced manufacturing, including the transformation of the company towards the Industry 4.0 model. Effective implementation and effective use of A&R solutions is possible only if the company has good prepared and educated employees. It applies to all levels, from the direct operation of machines and processes, through mid-level technical staff, to the management level. Nowadays, education of young staff, as well as training of those currently employed, requires the implementation of new solutions and methods of Vocational Education and Training (VET). They should ensure not only a high professional level, but also meet the challenges facing VET today: attractiveness of education for students, especially young ones, universal accessibility regardless of the place of residence, internationalization. The paper, presenting results of the MILAN project, shows that addressing those problems can largely be facilitated by the use of modern, advanced ICT solutions.
Investigation of the resistance, durability and abrasion of printed elements applied to sports equipment
Authors: Sidorov A , Iljin I 
Published: June 2022

Abstract
The work investigated the durability of the labelling of sports equipment made of composite materials. Professional hockey sticks were taken for research. Research has been done on hockey stick wear for different players: centre and winger and defender. In addition, a study was made of hockey sticks for left-handers and right-handers. In the study of the wear of printed elements, sports equipment of various lengths was used. Contact research was carried out during training and competition. The study of the number of contacts was carried out on the basis of video recordings of trainings and games of the teams “Energija” - ElektrÄnai (Lithuania) and the national team of the Belarusian Republic. The study carried out showed that the hockey stick wear of the centre striker and the winger during the competition and training is similar. During the competition, the hockey sticks of the centre strikers are most often in contact. It was found that the difference between contacts during training and playing depends on the intensity of the game, penalty time and strategy. When conducting a study of the wear of the printed elements applied to the hockey stick, depending on the position of the player, it was found that the wear of the sticks of the winger and the defender is the same, but that of the centre striker is different. When conducting a study of hockey stick wear depending on its length, the following conclusion was made: the taller the player, the longer his hockey stick and the maximum contact area. Research has shown that hockey stick wear is not affected by how the player holds the hockey stick, i.e. whether he is left-handed or right-handed. To study the abrasion of elements using the UGRA method, an original stand was created. With the help of this stand, studies of the abrasion of printed elements were carried out. Based on the study, it was concluded that the abrasion of printed elements most often occurs at the moment of contact of the objects of research, both with each other and with objects on the playing field. As a result, the printed elements split, peel off and become less noticeable, in addition, the name of the manufacturer's company is worn out and the hockey stick loses the player's personal identification data printed on the hockey stick. Recommendations are given on the peculiarities of printing and the location of printed elements on sports equipment.
Empirical analysis of piezoelectric stacks composed of plates with different parameters and excited with different frequencies
Authors: Harazin J , Wróbel A 
Published: June 2022

Abstract
Piezoelectric materials offer an ability to exchange energy between electrical and mechanical systems with fair ease, by using the simple and inverse piezoelectric effect. Piezoelectric transceivers, sensors, microphones, actuators, or active acoustic noise cancellation devices are some of many applications for piezoelectric materials. Due to the natural ability of the material to convert electricity and mechanical strain, solutions based on piezoelectric materials are often compact and allow applications on micro scales. One of the forms of piezoelectric actuation involves the use of piezoelectric stacks. The stack is composed of multiple piezoelectric plates layered by thin dielectric sheets, with electrodes attached along the sides. The main aim of piezoelectric stacks is the increase in maximum displacement by multiplying the number of piezoelectric plates that make up the stack. Stacks are composed of plates with the same material properties and the same dimensions. This study aims to investigate the idea of composing piezoelectric stacks of plates that have separate control circuits inducing different carrier frequencies or plates with differing properties and dimensions, in search for new applications for piezoelectric stacks. The main point of interest is the investigation of the ability to use piezoelectric stacks to generate complex vibration spectrums composed of multiple frequencies, resulting from the use of different piezoelectric plates in the stack or different carrier frequencies that stimulate each plate. To achieve this, a stack composed of two piezoelectric plates, each controlled by its own circuit, will be measured by a laser vibrometer, to check the complexity of the output vibration pattern.
Surface laser processing of maraging steel parts manufactured by selective laser melting: effect on pass geometry and hardness
Authors: Bučelis Kęstutis , Škamat Jelena , Černašejus Olegas 
Published: June 2022

Abstract
Due to the possibility to produce the parts with complex internal and external geometries, selective laser melting (SLM) process attracts growing interest in various fields of engineering segments such as aircraft, aerospace, biomedical, automotive, marine industries and tooling. Maraging steels, having excellent weldability and high resistance to thermal fatigue due to the lack of carbon, has showed good suitability for SLM [1]. However, owing to the limited hardness and wear resistance, maraging steels has limited application at the harsh wear conditions [4]. In this study, the possibility to improve the surface characteristics of DIN 1.2709 steel SLM parts by application of laser alloying technology is evaluated. The surface of SLM part was laser processed at various laser spot diameters and varying laser scanning speeds from 500 to 1500 mm⋅min-1, with and without preposition of alloying element. The power density was provided in the range from ~0.8⋅103 W⋅cm-2 to ~51⋅103 W⋅cm-2 and heat input – from 4 to 12 J⋅mm-1. The effect of laser processing parameters and presence of alloying element on the geometry of obtained processed passes and hardness of surface was evaluated. It was determined, that the application of CO2 continuous laser at the parameters of 1 kW laser power, 0.5 mm laser beam spot diameter and laser scanning speed in the range between 500 mm⋅min-1 and 1250 mm⋅min-1 allows obtaining laser pool of acceptable geometry and sizes directly on as-manufactured SLM part surface without any pre-processing. The increasing scanning speed to 1500 mm⋅min-1 or spot size to 2.0 and 3.0 mm results in too small pool depth and unstable pool geometry. The laser processing with preposition of alloying element layer provided surface alloying effect of the maraging steel SLM part. The hardness of processed surface areas ranged between ~600 HV0.2 at the lowest scanning speed and ~1770 HV0.2 at the highest speed, what is from 18% to ~3.5 times higher, as compared with maximum hardness of 1.2709 maraging steel after aging (~58 HRC or ~510 HV).