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1
Shi, Feng Xia, Jun Hu Yang, and Xiao Hui Wang. "Effect of Rotating Speed on Hydraulic Energy Recovery Turbines Performance." Applied Mechanics and Materials 444-445 (October 2013): 1033–37. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1033.
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In order to forecast the rotating speed of the hydraulic energy recovery turbine, Single centrifugal pump and single centrifugal pump with guide vane in reverse operation were adopted as turbines. 3D models were founded by pro/E software for turbines, Then the models were meshed by gambit and Simulated by fluent6.3 software. It was shown that before the best efficiency points, The higher the rotating speed, the lower the efficiency of turbine . but after the best efficiency points, the efficiency of turbine increased with the rise of rotating speed. with the rise of rotating speed ,the pressure in runner inlet was added, the amplitude of pressure pulse was added. the pressure distribution in runner inlet was more even of model B than that of model A. With a guide vane ,The steady scope of rotating speed in hydraulic energy recovery turbine was diminished,and the Controllability of rotating speed in hydraulic energy recovery turbines can be improved by guide vane. Some theories were offered for hydraulic energy recovery turbine researches.
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Zharkovskiy, A. A., V. A. Shchur, M. Omran, and A. A. Staseyev. "Automation of the design of the impeller of a radial-axial hydraulic turbine." Izvestiya MGTU MAMI 15, no. 4 (December 15, 2021): 18–26. http://dx.doi.org/10.31992/2074-0530-2021-50-4-18-26.
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The article describes approaches to the design of a vane system of radial-axial hydraulic turbines based on an automated design system developed at SPbPU using the Python programming language. The specified system currently includes the following modules: selection of the main parameters of the hydraulic turbine, construction of the meridional projection of the impeller, calculation of the potential flow and construction of the blade system of the radial-axial hydraulic turbine. The choice of the main parameters of the hydraulic turbine is based on the technique generally accepted in hydraulic turbine engineering, which has been digitized and introduced into the software package. The paper considers and analyzes different approaches to the design of the meridional bypasses of the flow path in the area of the impeller of a radial-axial hydraulic turbine, a comparison of the results of their construction using different methods is given. A technique that is most suitable for algorithmization in the software package based on the results of the analysis was selected. The construction of streamlines and the calculation of velocities along them are presented on the basis of the calculation of the potential flow in the meridian section. The design of the blade system of the hydraulic turbine was carried out by the method of solving the direct axisymmetric problem of the theory of hydraulic machines. As an example, a blade system of a radial-axial hydraulic turbine was designed for a head up to 75 meters, the initial parameters of which correspond to hydraulic turbines-analogues of similar speed. The designed hydro turbine was calculated in Ansys, and the results confirmed its excellent energy properties. It is planned to further develop the software package in terms of automatic construction of 3-dimensional solid models of the flow path, which can later be calculated by the methods of computational fluid dynamics and optimized to obtain hydraulic turbines with parameters corresponding to the current state of the art.
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Ayancik, Fatma, Erdem Acar, Kutay Celebioglu, and Selin Aradag. "Simulation-based design and optimization of Francis turbine runners by using multiple types of metamodels." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 8 (June 29, 2016): 1427–44. http://dx.doi.org/10.1177/0954406216658078.
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In recent years, optimization started to become popular in several engineering disciplines such as aerospace, automotive and turbomachinery. Optimization is also a powerful tool in hydraulic turbine industry to find the best performance of turbines and their sub-elements. However, direct application of the optimization techniques in design of hydraulic turbines is impractical due to the requirement of performing computationally expensive analysis of turbines many times during optimization. Metamodels (or surrogate models) that can provide fast response predictions and mimic the behavior of nonlinear simulation models provide a remedy. In this study, simulation-based design of Francis type turbine runner is performed by following a metamodel-based optimization approach that uses multiple types of metamodels. A previously developed computational fluid dynamics-based methodology is integrated to the optimization process, and the results are compared to the results obtained from on-going computational fluid dynamics studies. The results show that, compared to the conventional methods such as computational fluid dynamics-based methods, metamodel-based optimization can shorten the design process time by a factor of 9.2. In addition, with the help of optimization, turbine performance is increased while cavitation on the turbine blades, which can be harmful for the turbine and reduce its lifespan, is reduced.
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Martineau Rousseau, Philippe, Azzeddine Soulaïmani, and Michel Sabourin. "Efficiency Assessment for Rehabilitated Francis Turbines Using URANS Simulations." Water 13, no. 14 (July 7, 2021): 1883. http://dx.doi.org/10.3390/w13141883.
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Due to the large number of aging hydraulic turbines in North America, rehabilitation is a growing market as these turbines have low efficiency compared to modern ones. Computational Fluid Dynamics identifies components with poor hydraulic performance. The models often used in industry are based on individually analyzing the sub-components of a turbine instead of full turbine simulations due to computational and time limitations. An industrial case has shown that such analyses may lead to underestimating the efficiency increases by modifying the stay vane. The unsteady full turbine simulation proposes to simulate all components simultaneously to assess this efficiency augmentation due to stay vane rehabilitation. The developed simulation methodology is used to evaluate the efficiency increase and the flow of two rehabilitated turbines with stay vane modifications. Comparison with model tests shows the accuracy of the simulations. However, the methodology used shows imprecision in predicting the efficiency increase compared to model tests. Further works should consider the use of more complex flow modeling methods to measure the efficiency increase by the stay vane modifications.
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Seifollahi Moghadam, Zahra, François Guibault, and André Garon. "On the Evaluation of Mesh Resolution for Large-Eddy Simulation of Internal Flows Using Openfoam." Fluids 6, no. 1 (January 5, 2021): 24. http://dx.doi.org/10.3390/fluids6010024.
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The central aim of this paper is to use OpenFOAM for the assessment of mesh resolution requirements for large-eddy simulation (LES) of flows similar to the ones which occur inside the draft-tube of hydraulic turbines at off-design operating conditions. The importance of this study is related to the fact that hydraulic turbines often need to be operated over an extended range of operating conditions, which makes the investigation of fluctuating stresses crucial. Scale-resolving simulation (SRS) approaches, such as LES and detached-eddy simulation (DES), have received more interests in the recent decade for understanding and mitigating unsteady operational behavior of hydro turbines. This interest is due to their ability to resolve a larger part of turbulent flows. However, verification studies in LES are very challenging, since errors in numerical discretization, but also subgrid-scale (SGS) models, are both influenced by grid resolution. A comprehensive examination of the literature shows that SRS for different operating conditions of hydraulic turbines is still quite limited and that there is no consensus on mesh resolution requirement for SRS studies. Therefore, the goal of this research is to develop a reliable framework for the validation and verification of SRS, especially LES, so that it can be applied for the investigation of flow phenomena inside hydraulic turbine draft-tube and runner at their off-design operating conditions. Two academic test cases are considered in this research, a turbulent channel flow and a case of sudden expansion. The sudden expansion test case resembles the flow inside the draft-tube of hydraulic turbines at part load. In this study, we concentrate on these academic test cases, but it is expected that hydraulic turbine flow simulations will eventually benefit from the results of the current research. The results show that two-point autocorrelation is more sensitive to mesh resolution than energy spectra. In addition, for the case of sudden expansion, the mesh resolution has a tremendous effect on the results, and, so far, we have not capture an asymptotic converging behavior in the results of Root Mean Square (RMS) of velocity fluctuations and two-point autocorrelation. This case, which represents complex flow behavior, needs further mesh resolution studies.
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Skripkin, Sergey, Mikhail Tsoy, and Sergey Shtork. "Experimental Investigation Of Double Precessing Vortex Rope Forming In Draft Tube Models." Siberian Journal of Physics 10, no. 2 (June 1, 2015): 73–82. http://dx.doi.org/10.54362/1818-7919-2015-10-2-73-82.
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This work is devoted to the experimental research of the flow structure in draft tube models of hydro turbines. Precessing vortex core was formed using fixed swirler in a flow such as observed in natural hydro turbines under off-design conditions. In laboratory conditions it has been able to find the effect of the transition between single- and double- vortex rope. Their frequency characteristics have been measured in the range of Reynolds numbers 5·104 –5·105 . Based on the analysis of data high-speed shooting the mechanism of complete transition between single and double vortex modes was investigated in detail. The investigation of this phenomenon is of particular interest for the design and operation of hydraulic turbine equipment due to off-design pressure pulsations with sudden changes in frequency and amplitude in a flow occurring.
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Šiško Kuliš, Marija, Nikola Mijalić, and Senad Hidžić. "Cavitation Detection on Hydraulic Machines." Journal of Energy - Energija 70, no. 3 (August 16, 2022): 25–32. http://dx.doi.org/10.37798/202170328.
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This paper gives an engineering review of the phenomenon of cavitation on hydraulic machines: turbines, pumps and ships propellers. The types of cavitation and its consequences are presented by the cabinet study of the results of relevant researches on models and real plants. In the special focus of this paper are the techniques of exploration of cavitation erosion: visual examination, measurements of pressures and vibrations and CFD methods.
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McKinnon, Conor, James Carroll, Alasdair McDonald, Sofia Koukoura, and Charlie Plumley. "Investigation of Isolation Forest for Wind Turbine Pitch System Condition Monitoring Using SCADA Data." Energies 14, no. 20 (October 13, 2021): 6601. http://dx.doi.org/10.3390/en14206601.
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Wind turbine pitch system condition monitoring is an active area of research, and this paper investigates the use of the Isolation Forest Machine Learning model and Supervisory Control and Data Acquisition system data for this task. This paper examines two case studies, turbines with hydraulic or electric pitch systems, and uses an Isolation Forest to predict failure ahead of time. This novel technique compared several models per turbine, each trained on a different number of months of data. An anomaly proportion for three different time-series window lengths was compared, to observe trends and peaks before failure. The two cases were compared, and it was found that this technique could detect abnormal activity roughly 12 to 18 months before failure for both the hydraulic and electric pitch systems for all unhealthy turbines, and a trend upwards in anomalies could be found in the immediate run up to failure. These peaks in anomalous behaviour could indicate a future failure and this would allow for on-site maintenance to be scheduled. Therefore, this method could improve scheduling planned maintenance activity for pitch systems, regardless of the pitch system employed.
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McKinnon, Conor, James Carroll, Alasdair McDonald, Sofia Koukoura, and Charlie Plumley. "Investigation of Isolation Forest for Wind Turbine Pitch System Condition Monitoring Using SCADA Data." Energies 14, no. 20 (October 13, 2021): 6601. http://dx.doi.org/10.3390/en14206601.
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Wind turbine pitch system condition monitoring is an active area of research, and this paper investigates the use of the Isolation Forest Machine Learning model and Supervisory Control and Data Acquisition system data for this task. This paper examines two case studies, turbines with hydraulic or electric pitch systems, and uses an Isolation Forest to predict failure ahead of time. This novel technique compared several models per turbine, each trained on a different number of months of data. An anomaly proportion for three different time-series window lengths was compared, to observe trends and peaks before failure. The two cases were compared, and it was found that this technique could detect abnormal activity roughly 12 to 18 months before failure for both the hydraulic and electric pitch systems for all unhealthy turbines, and a trend upwards in anomalies could be found in the immediate run up to failure. These peaks in anomalous behaviour could indicate a future failure and this would allow for on-site maintenance to be scheduled. Therefore, this method could improve scheduling planned maintenance activity for pitch systems, regardless of the pitch system employed.
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Purece, Cristian, Vasile Pleşca, and Lilica Corlan. "Technologies for obtaining energy from micro-hydropower resources." Technium: Romanian Journal of Applied Sciences and Technology 2, no. 4 (June 16, 2020): 124–33. http://dx.doi.org/10.47577/technium.v2i4.837.
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Currently the global demand for electricity and drinking water is constantly increasing. Given its many economic, social and environmental benefits, hydro energy will be an important contributor to the energy mix of the future. Isolated areas, heavily underdeveloped regions, disaster-affected areas have a common need of easy-to-use means to generate electricity. The most efficient way to meet these needs involves the use of various renewable energy resources available locally. One of the main sources of renewable energy is hydro energy, more specifically micro-hydro energy. However, hydropower projects involve various considerations at different levels of project implementation. To make the most of the available hydropower potential, new models of hydraulic turbines were developed. For a cost-effective and efficient hydropower project, the selection of the hydraulic turbine must be optimally studied. The objective of the present work is to carry out a review of the optimum selection mode of the hydraulic turbine that equips a micro hydropower plant (MHP).
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Hamarasheed, Chalang, Sallehuddin Mohamed Haris, and Zulkifli Mohd Nopiah. "Weighted Multiple Model Adaptive PID Control with Crossover Frequency Shift Tuning for a Hydraulic Turbine Plant." Applied Mechanics and Materials 278-280 (January 2013): 1644–47. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.1644.
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Hydraulic turbines are known to have complex and highly nonlinear dynamics with some varying parameters, especially in the presence of large or abrupt disturbances. In this study, the weighted multiple model adaptive control scheme was used as a controller for a hydraulic turbine model, with the aim of providing desirable characteristics such as robustness and stability. The system of comprised four candidate plant models with four corresponding candidate PID controllers which were tuned according to the phase shifting method. The plant operation, subjected to both abruptly changing and smoothly changing load conditions, was simulated. From the results, it was found that the proposed controller showed very good performance for both types of disturbance changes.
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Madeira, Filipe C., João F. P. Fernandes, Modesto Pérez-Sánchez, P. Amparo López-Jiménez, Helena M. Ramos, and P. J. Costa Branco. "Electro-Hydraulic Transient Regimes in Isolated Pumps Working as Turbines with Self-Excited Induction Generators." Energies 13, no. 17 (September 1, 2020): 4521. http://dx.doi.org/10.3390/en13174521.
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The use of pumps working as turbines (PATs) is a sustainable technical measure that contributes to the improvement of energy efficiency in water systems. However, its performance analysis in off-grid recovery systems is a complex task that must consider both hydraulic (PAT) and electrical machines (typically a self-excited induction generator-SEIG). Aside from several kinds of research that analyze the PAT-SEIG behavior under steady-state constant hydraulic and electrical conditions, this research focuses on the analysis of PAT-SEIG transient regimes, by analyzing their variation when a sudden change occurs in the hydraulic or electrical components. Analytical models were developed to represent the operation of SEIG, PAT, and the PAT-SEIG coupled system. Hydraulic and electromechanical experimental tests validated these models. An excellent fit was obtained when analytical and experimental values were compared. With these models, the impact on the operation of the PAT-SEIG system was examined when sudden change occurred in the excitation capacitances, resistive loads, or recovered head. With a sudden increase of resistive load, the hydraulic power and SEIG stator current remain almost constant. However, there is an increase of SEIG reactive power, decreasing the PAT-SEIG efficiency. Also, with a sudden increase of SEIG capacitors or PAT hydraulic head, the SEIG stator current increases once and not again, while PAT-SEIG efficiency decreases, but the induction generator can be overloaded. The development of this research is key to the advancement of future models which can analyze the coupling of micro-hydropower solutions.
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Moraga, G., C. Valero, D. Valentín, M. Egusquiza, X. Xia, L. Zhou, and A. Presas. "Characterization of the Fluid Damping in Simplified Models of Pump-Turbines and High Head Francis Runners." IOP Conference Series: Earth and Environmental Science 1079, no. 1 (September 1, 2022): 012091. http://dx.doi.org/10.1088/1755-1315/1079/1/012091.
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Abstract In order to satisfy the power demand in the electrical grid, hydraulic turbine units frequently work under off-design operation conditions and pass through transient events. These operation conditions can lead to high vibration amplitudes in the turbine runners, decreasing their useful life, and in some cases to premature failures. To determine and to understand the behaviour of the fluid damping is a relevant topic, because this parameter limits the maximum amplitude in resonance conditions. The runner of some types of turbines, such as reversible pump-turbine and high head Francis turbine, can be modelled as a disk-like structure, due to their similar mode shapes. Because of this, in this work, the fluid damping of a vibrating disk was studied. The disk was submerged in water and was put in a resonant state at different vibration amplitudes. Moreover, this structure was excited at different distances to a rigid surface, in order to analyse the effects of the distance between the runner and the casing. The main effects on the fluid damping were determined and characterized, showing a dependency of the fluid damping ratio on the different parameters.
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Poteraş, George, György Deák, Iasmina-Florina Burlacu, Simona Natalia Raischi, and Violeta-Monica Radu. "Use of the bio-engineering technologies in the construction and upgrade of complex installations for obtaining energy from three renewable sources. Complex installations for flowing waters." E3S Web of Conferences 239 (2021): 00009. http://dx.doi.org/10.1051/e3sconf/202123900009.
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In the context of the sustainable development, the problem of the widespread use of renewable energy resources, which are clean and inexhaustible, is becoming more acute. In this regard, it is necessary to develop some capture installations that use renewable energy sources as efficiently as possible and with low impact on the environment. This paper presents a patented installation that integrates three sources of renewable energy: wind energy, solar energy and hydraulic energy of water current. The efficiency of this complex installation is given by the fact that the simultaneous capitalization of the three renewable energy sources leads to a high efficiency, in relation with the occupied area. To increase the renewable energy absorption level, both the air turbine and the hydraulic turbine have been equipped with different bioengineering models of blades and paddles. Following the testing of the two turbines equipped with blades and paddles with bioengineering geometry, a significant improvement of their efficiency was found, compared to the initial blades and paddles.
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Stammler, Matthias, Fabian Schwack, Norbert Bader, Andreas Reuter, and Gerhard Poll. "Friction torque of wind-turbine pitch bearings – comparison of experimental results with available models." Wind Energy Science 3, no. 1 (March 14, 2018): 97–105. http://dx.doi.org/10.5194/wes-3-97-2018.
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Abstract. Pitch bearings of wind turbines are large, grease-lubricated rolling bearings that connect the rotor blades with the rotor hub. They are used to turn the rotor blades to control the power output and/or structural loads of the turbine. Common actuators turning the blades are hydraulic cylinders or electrical motor–gearbox combinations. In order to design pitch actuator systems that are able to turn the blades reliably without imposing an excessive power demand, it is necessary to predict the friction torque of pitch bearings for different operating conditions. In this paper, the results of torque measurements under load are presented and compared to results obtained using different calculation models. The results of this comparison indicate the various sources of friction that should be taken into account for a reliable calculation model.
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Georgievskaia, E. V. "APPLICATION OF BREAKDOWN MECHANICS FOR PREDICTING THE RESOURCE OF AXIAL RADIAL HYDROTURBINS." Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS 20, no. 9-10 (January 24, 2019): 71–78. http://dx.doi.org/10.30724/1998-9903-2018-20-9-10-71-78.
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To plan for timely reconstruction, modernization, repairs or replacement of equipment it is important to reliably predict the instant of its transition to the limiting state that determines the lifetime. Currently, there are no regulatory methods for assessing the lifetime of hydraulic turbines at the operation stage. The approach presented in this paper uses the fracture mechanics methods to build a long-term individual forecast of the dangerous development defects in the main elements of hydraulic turbines taking into account design, technological and operational features. The forecast is based on three-dimensional mathematical models that describe the change in the technical condition of the equipment during time under actual operation. The ANSYS software is used for calculations. Models take into account the size and position of detected or possible defects. Crack growth is determined by the combination of low- and high-frequency loads. The critical length of the crack corresponds to the instant of change of the crack development mechanism, when the failure risk increases sharply. Proposed approach can significantly reduce the possibility of unplanned or emergency shutdown of the hydraulic unit due to its destruction during the overhaul period.
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Unterluggauer, Julian, Anton Maly, and Eduard Doujak. "Investigation on the Impact of Air Admission in a Prototype Francis Turbine at Low-Load Operation." Energies 12, no. 15 (July 27, 2019): 2893. http://dx.doi.org/10.3390/en12152893.
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Due to significant changes in the energy system, hydraulic turbines are required to operate over a wide power range. In particular, older turbines which are not designed for these environments will suffer under off-design conditions. In order to evaluate whether or not such a turbine could fulfill the new requirements of the energy market, a study about the behavior of a prototype plant in low-load operation is presented. Therefore, prototype site measurements are performed to determine the most damaging operating point by means of acceleration sensors and pressure transducers. Moreover, unsteady computational fluid dynamics (CFD) simulations considering two-phase flow and two hybrid turbulence models are used to analyze the flow conditions inside the turbine. The resulting pressure pulsations are mapped onto the runner blade to obtain stress and further calculate damage factors. Accordingly, the stresses are compared to those obtained by the strain gauge measurement. Moreover, the influence of active flow control by means of air injection on plant behavior and runner lifetime is discussed as well.
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Petrochenkov, Anton, Aleksandr Romodin, Vladimir Kazantsev, Aleksey Sal’nikov, Sergey Bochkarev, Yuri Gagarin, Ruslan Shapranov, and Pavel Brusnitcin. "Principles of Imitation for the Loading of the Test Bench for Gas Turbines of Gas Pumping Units, Adequate to Real Conditions." Sustainability 13, no. 24 (December 10, 2021): 13678. http://dx.doi.org/10.3390/su132413678.
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The purpose of the study is to analyze the prospects for the development of loading methods for gas turbines as well as to develop a mathematical model that adequately describes the real operating conditions of the loading system at various loads and rotation speeds. A comparative analysis of the most common methods and technical means of loading the shafts of a free turbine at gas turbine plants intended for operation as part of gas pumping units is presented. Based on the results of the analysis, the expediency of using the loading model “Free Power Turbine Rotor–Hydraulic Brake” as a load simulation is shown. Recommendations for the creation of an automation system for the load testing of power plants have been developed. Mathematical models and Hardware-in-the-Loop simulation models of power plants have been developed and tested. One of the most important factors that predetermine the effectiveness of the loading principle is the possibility of software implementation of the loading means using software control systems that provide the specified loading parameters of the gas turbine.
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Decaix, Jean, Vlad Hasmatuchi, Maximilian Titzschkau, and Cécile Münch-Alligné. "CFD Investigation of a High Head Francis Turbine at Speed No-Load Using Advanced URANS Models." Applied Sciences 8, no. 12 (December 5, 2018): 2505. http://dx.doi.org/10.3390/app8122505.
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Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by, and shut-down procedures, which reduces the lifespan of the machines. CFD based on standard URANS turbulence modeling is currently able to predict accurately the performances of the hydraulic turbines for operating points close to the Best Efficiency Point (BEP). However, far from the BEP, the standard URANS approach is less efficient to capture the dynamics of 3D flows. The current study focuses on a hydraulic turbine, which has been investigated at the BEP and at the Speed-No-Load (SNL) operating conditions. Several “advanced” URANS models such as the Scale-Adaptive Simulation (SAS) SST k - ω and the BSL- EARSM have been considered and compared with the SST k - ω model. The main conclusion of this study is that, at the SNL operating condition, the prediction of the topology and the dynamics of the flow on the suction side of the runner blade channels close to the trailing edge are influenced by the turbulence model.
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Sun, Shuaihui, Pei Ren, Pengcheng Guo, Longgang Sun, and Xiaobo Zheng. "Influence of the Gas Model on the Performance and Flow Field Prediction of a Gas–Liquid Two-Phase Hydraulic Turbine." Energies 15, no. 17 (August 30, 2022): 6325. http://dx.doi.org/10.3390/en15176325.
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A two-phase hydraulic turbine’s performance and flow field were predicted under different Inlet Gas Volume Fractions (IGVF) with incompressible and compressible models, respectively. The calculation equation of equivalent head, hydraulic efficiency, and flow loss considering the expanding work of compressible gas were deduced based on the energy conservation equations. Then, the incompressible and compressible results, including the output power and flow fields, are compared and analyzed. The compressible gas model’s equivalent head, output power, and flow loss are higher than the incompressible model, but the hydraulic efficiency is lower. As the IGVF increases, the gas gradually diffuses from the blade’s working surface to its suction surface. The gas–liquid separation happens at the runner outlet in the compressible results due to the gas expansion. The area of the low-pressure zone in the incompressible results increases with the IGVF. However, it decreases with the IGVF in the compressible results. As the gas expands in the blade passage, it takes up more flow area, causing the high liquid velocity in the same passage. The runner’s inlet gas distribution affects the liquid flow angle, causing the inlet shock and high TKE areas, especially in the blade passage near the volute tongue. The high TKE area in the compressible results is larger than the incompressible results because the inlet impact loss and the liquid velocity in the blade passage are higher. This paper provides a reference for selecting gas models in the numerical simulation of two-phase hydraulic turbines.
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Lopez Mejia, Omar D., Oscar E. Mejia, Karol M. Escorcia, Fabian Suarez, and Santiago Laín. "Comparison of Sliding and Overset Mesh Techniques in the Simulation of a Vertical Axis Turbine for Hydrokinetic Applications." Processes 9, no. 11 (October 28, 2021): 1933. http://dx.doi.org/10.3390/pr9111933.
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The application of Computational Fluid Dynamics (CFD) to energy-related problems has increased in the last decades in both renewable and conventional energy conversion processes. In recent years, the application of CFD in the study of hydraulic, marine, tidal, and hydrokinetic turbines has focused on the understanding of the details of the complex turbulent flow and also in improving the prediction of the performance of these devices. There are several complexities involved in the simulation of Vertical Axis Turbine (VAT) for hydrokinetic applications. One of them is the necessity of a dynamic mesh model. Typically, the model used in the simulation of these devices is the sliding mesh technique, but in recent years the fast development of the overset (also known as chimera) mesh technique has caught the attention of the academic community. In the present paper, a comparison between these two techniques is done in order to establish their advantages and disadvantages in the two-dimensional simulation of vertical axis turbines. The comparison was done not only for the prediction of performance parameters of the turbine but also for the capabilities of the models to capture complex flow phenomena in these devices and computational costs.
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Astolfi, Davide, Ravi Pandit, Ludovica Celesti, Matteo Vedovelli, Andrea Lombardi, and Ludovico Terzi. "Data-Driven Assessment of Wind Turbine Performance Decline with Age and Interpretation Based on Comparative Test Case Analysis." Sensors 22, no. 9 (April 21, 2022): 3180. http://dx.doi.org/10.3390/s22093180.
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An increasing amount of wind turbines, especially in Europe, are reaching the end of their expected lifetimes; therefore, long data sets describing their operation are available for scholars to analyze the performance trends. On these grounds, the present work is devoted to test case studies for the evaluation and the interpretation of wind turbine performance decline with age. Two wind farms were studied, featuring widely employed wind turbine models: the former is composed of 6 Senvion MM92 and the latter of 11 Vestas V52 wind turbines, owned by the ENGIE Italia company. SCADA data spanning, respectively, 10 and 7 years were analyzed for the two test cases. The effect of aging on the performance of the test case wind turbines was studied by constructing a data-driven model of appropriate operation curves, selected depending on the working region. For the Senvion MM92, we found that it is questionable to talk about performance aging because there is no evident trend in time: the performance variation year by year is in the order of a few kW and is therefore irrelevant for practical applications. For the Vestas V52 wind turbines, a much wider variability is observed: two wind turbines are affected by a remarkable performance drop, after which the behavior is stable and under-performing with respect to the rest of the wind farm. Particular attention is devoted to the interpretation of the results: the comparative discussion of the two test cases indicates that the observed operation curves are compatible with the hypothesis that the worsening with age of the two under-performing Vestas V52 can be ascribed to the behavior of the hydraulic blade pitch. Furthermore, for both test cases, it is estimated that the gearbox-aging contributes negligibly to the performance decline in time.
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Sinagra, Marco, Tullio Tucciarelli, Calogero Picone, Costanza Aricò, and Marwa Hannachi. "Design of Reliable and Efficient Banki-Type Turbines." Environmental Sciences Proceedings 2, no. 1 (September 5, 2020): 49. http://dx.doi.org/10.3390/environsciproc2020002049.
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A new shape for the external surface of the Crossflow turbine blades is proposed, which allows for the preservation of hydraulic efficiency in spite of a significant maximum blade thickness providing mechanic robustness and reliability. The final shape of the blades is assessed using an iterative solution for two uncoupled models: a 2D computational fluid dynamic (CFD) and a structural 3D finite element method (FEM) analysis of a single blade. Application of the proposed methodology to the design of a power recovery system (PRS) turbine, a new backpressure Crossflow-type inline turbine for pressure regulation, and energy production in a real Sicilian site follows.
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Kocsis, Gergely, and George Xydis. "An Evaluation Framework on Additive Manufacturing for Hydraulic Systems in Wind Turbines Focused on System Simplification." Modelling 2, no. 2 (June 19, 2021): 327–43. http://dx.doi.org/10.3390/modelling2020017.
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The wind energy industry showed rapid growth in the past decade, pushing designs to the physical limits. In the last few years, the exponential growth of the wind turbine sizes capped, and the performance upgrades are reached with optimization processes. The first wave was on major parts, but with time advancing the “cost out” strategies are pushed to minor components. A major problem is service costs and the continuous search for missing spare parts in the market. The main aim of this study is to identify when is the best entry point for the additive manufacturing (AM) technology by the hydraulic manufacturer wind turbine companies. From the commercial application for expensive prototypes, it has evolved to economical home use applications. The newly available machines allow printing parts with competing precision to machining equivalents. The material selections range from plastics to metals with mechanical properties equally good or better. This project aims to provide a comprehensive review of the implementation of AM for hydraulic systems in wind turbines. Application screening was done by desk research and on AM technologies. Scientific research has been found on the topic for benchmarking, viability, and cost models. It has been found that there are still missing data for the mechanical properties of the available materials. The result of the decision-weighted matrix shows that the business could gain a competitive advantage by the AM implementation in terms of resources savings and productivity. Although from the technological and market perspective it is justified to initiate before further action the business should review its organization viability.
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Chihaia, Rareş-Andrei, Lucia-Andreea El-Leathey, Gabriela Cîrciumaru, and Nicolae Tănase. "Increasing the energy conversion efficiency for shrouded hydrokinetic turbines using experimental analysis on a scale model." E3S Web of Conferences 85 (2019): 06004. http://dx.doi.org/10.1051/e3sconf/20198506004.
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The objective of the paper is to study the influence of certain shroud types suitable for horizontal axis hydrokinetic turbines using experimental testing in order to increase the energy conversion efficiency. The scale model of the shrouded hydrokinetic turbine is tested on a dedicated experimental bench for axial hydraulic turbine models. Two types of shrouds were tested in order to be compared: convergent shroud and divergent shroud. The rotor and shroud were made using 3D printer technology and were tested at a water velocity of 0.9 m/s on the closed-circuit testing bench. The testing facility allows the determination of the power extracted for each shroud at five distinct positions. Thus, the rotor can be moved within the shroud from inlet to outlet in order to establish the proper operating position. The mechanical power is measured using a torque transducer and an electromagnetic particle brake. The testing results will be analysed based on the variation of power curves obtained for different shroud types and operating positions. The optimum design and the best operating position will be recommended by comparing the testing result with the data collected from the bare turbine using the same rotor placed directly in free flow.
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Vodka, Oleksii, Yuliia Viazovychenko, Oleksiy Larin, and Kseniia Potopalska. "Computer modeling of the stress state and reliability assessment of bolted connections of the rotor and runner of Kaplan turbines." Bulletin of the National Technical University «KhPI» Series: Dynamics and Strength of Machines, no. 2 (December 31, 2022): 68–74. http://dx.doi.org/10.20998/2078-9130.2022.2.271065.
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Ensuring the trouble-free operation of hydroelectric power stations is an important element of the stability of the power grid. Hydraulic turbines are often used to regulate daily fluctuations in electricity consumption. It is the start/stop modes of the hydraulic unit that are the most dangerous and lead to the highest levels of mechanical stress. Therefore, the work is devoted to the development of detailed three-dimensional models for assessing the stress state of bolted connections of the impeller, and on their basis determining the stress state in different operating modes of the hydraulic unit. The similarity method based on known experimental data is used to determine the load acting on the bolted connection. Determination of the stress state is carried out using the finite element method. The developed three-dimensional detailed finite-element model takes into account the non-linear interaction between the connecting parts: the bolt, the shaft flange, and the impeller body. Determined stresses as a function of time, which occur during the start/stop of the hydraulic unit and are used to estimate the life (including the residual) of the bolted connection.
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Aryal, Shekhar, Sailesh Chitrakar, Rajendra Shrestha, and Ajay kumar Jha. "Credibility of Rotating Disc Apparatus for investigating sediment erosion in guide vanes of Francis turbines." IOP Conference Series: Earth and Environmental Science 1037, no. 1 (June 1, 2022): 012034. http://dx.doi.org/10.1088/1755-1315/1037/1/012034.
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Abstract Estimation of sediment erosion in hydraulic turbines is limited by the broad range of dependent parameters, such as characteristics of sediment, base materials and flow conditions. Some mathematical models have been proposed in the past literatures and some of them has been incorporated in a CFD tool for predicting the erosion together with the flow conditions. Rotating Disc Apparatus is a simplified experimental setup that was initially developed targeting on erosion studies in Francis turbines. However, the closeness of the results obtained from this apparatus with the actual turbine remains uncertain. This paper focuses on investigating the flow phenomena inside the region of guide vanes using RDA and comparing with the actual turbine. A reference case of Jhimruk hydropower plant has been taken in this study, which has been scaled down with a factor of 1.6 from its original size. The numerical fluid domain consists of four rotating blades distributed around the disc uniformly. The pressure distribution around the guide vanes inside RDA along with development of the tip-vortices have been compared with the results from the past research works. The experiment consists of a qualitative analysis of the wear pattern, which has been compared with the results of the CFD. It is found that flow field around guide vanes inside RDA matches closely with that of the real turbine. The stagnation point and development of the pressure and suction sides are similar to the actual guide vanes, which makes the apparatus suitable for investigating the erosion after including the sediment particles. However, more investigations might be needed for using the same apparatus for the runner blades, or guide vanes at different operating conditions.
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Amelio, Mario, Silvio Barbarelli, and Domenico Schinello. "Review of Methods Used for Selecting Pumps as Turbines (PATs) and Predicting Their Characteristic Curves." Energies 13, no. 23 (December 1, 2020): 6341. http://dx.doi.org/10.3390/en13236341.
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The use of Pumps As Turbines (PATs) can be the best solution for exploiting small hydraulic resources. Pump manufacturers do not provide the performances of their machines running in reverse mode, thus several authors developed appropriate prediction models. Some of them can only correlate the pump Best Efficiency Point (BEP) to the PAT corresponding one; other ones are able to obtain the characteristic curves. In this paper, a review of these methodologies is presented with the aim to find the best strategy that allows a designer of a small hydropower plant to select the PAT to be used and to predict its characteristic curves. The study also highlights the possibility of disassembling some models in order to merge the best parts in a more reliable strategy.
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Iovănel, Raluca Gabriela, Arash Soltani Dehkharqani, Diana Maria Bucur, and Michel Jose Cervantes. "Numerical Simulation and Experimental Validation of a Kaplan Prototype Turbine Operating on a Cam Curve." Energies 15, no. 11 (June 3, 2022): 4121. http://dx.doi.org/10.3390/en15114121.
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The role of hydropower has become increasingly essential following the introduction of intermittent renewable energies. Quickly regulating power is needed, and the transient operations of hydropower plants have consequently become more frequent. Large pressure fluctuations occur during transient operations, leading to the premature fatigue and wear of hydraulic turbines. Investigations of the transient flow phenomena developed in small-scale turbine models are useful and accessible but limited. On the other hand, experimental and numerical studies of full-scale large turbines are challenging due to production losses, large scales, high Reynolds numbers, and computational demands. In the present work, the operation of a 10 MW Kaplan prototype turbine was modelled for two operating points on a propeller curve corresponding to the best efficiency point and part-load conditions. First, an analysis of the possible means of reducing the model complexity is presented. The influence of the boundary conditions, runner blade clearance, blade geometry and mesh size on the numerical results is discussed. Secondly, the results of the numerical simulations are presented and compared to experimental measurements performed on the prototype in order to validate the numerical model. The mean torque and pressure values were reasonably predicted at both operating points with the simplified model. An analysis of the pressure fluctuations at part load demonstrated that the numerical simulation captured the rotating vortex rope developed in the draft tube. The frequencies of the rotating and plunging components of the rotating vortex were accurately captured, but the amplitudes were underestimated compared to the experimental data.
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Xu, Xinyong, Jinchang Liang, Wenjie Xu, Rui Liang, Jun Li, and Li Jiang. "Reinforced Concrete Wind Turbine Towers: Damage Mode and Model Testing." Sustainability 14, no. 8 (April 7, 2022): 4410. http://dx.doi.org/10.3390/su14084410.
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This study investigates the complex load-bearing mechanism of the reinforced concrete tower of large wind turbines through a structural model test. MTS electro-hydraulic servo loading system was used to load two reinforced concrete tower models for the push-out test. The ultimate bearing capacity of the reinforced concrete tower was found to be 8.894 kN. The test findings revealed that the top of the tower is subjected to unilateral shear as the horizontal load increases. As a result, the concrete strain in the compression zone of the test piece increases to its highest level in the bottom plastic hinge area. The concrete in the compression zone is being crushed in the meantime. The reinforcement achieves its yield point and deforms within the range of plastic failure when subjected to extreme loads. The outcomes of this study serve as a foundation for the running of wind turbines in extreme conditions.
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Plua, Frank A., Francisco-Javier Sánchez-Romero, Victor Hidalgo, P. Amparo López-Jiménez, and Modesto Pérez-Sánchez. "New Expressions to Apply the Variation Operation Strategy in Engineering Tools Using Pumps Working as Turbines." Mathematics 9, no. 8 (April 14, 2021): 860. http://dx.doi.org/10.3390/math9080860.
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The improvement in energy saving aspects in water systems is currently a topic of major interest. The utilization of pumps working as turbines is a relevant strategy in water distribution networks consisting of pressurized pipes, using these machines to recover energy, generate green energy and reduce leakages in water systems. The need to develop energy studies, prior to the installation of these facilities, requires the use of simulation tools. These tools should be able to define the operation curves of the machine as a function of the flow rate. This research proposes a new strategy to develop a mathematics model for pumps working as turbines (PATs), considering the modified affinity laws. This proposed model, which can be input into hydraulic simulation tools (e.g., Epanet, WaterGems), allows estimation of the head, efficiency, and power curves of the PATs when operating at different rotational speeds. The research used 87 different curves for 15 different machines to develop the new model. This model improves the results of the previously published models, reducing the error in the estimation of the height, efficiency, and power values. The proposed model reduced the errors by between 30 and 50% compared to the rest of the models.
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Galvis-Holguin, Steven, Jorge Sierra-Del Rio, and D. Hincapié-Zuluaga. "Enhancement efficiency of Michell-Banki turbine using NACA 6512 modified blade profile via CFD." EUREKA: Physics and Engineering, no. 2 (March 31, 2022): 55–67. http://dx.doi.org/10.21303/2461-4262.2022.002351.
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The small hydroelectric power plants (SHPP) are implemented in non-interconnected zones (NIZ) of developing countries. In which, the provision of electrical energy from the national interconnected system is not economically feasible. Therefore, in the literature, hydroelectric generation technologies have been implemented taking advantage of the energy available in the rivers. One of these technologies is the Michell-Banki type cross-flow turbines (MBT), which, despite having lower efficiencies than turbines such as Pelton and Francis, maintain their efficiency although fluctuations in site conditions. For this reason, different studies have been made to increase the efficiency of the MBT by making geometric modifications to both the nozzle and the rotor.
The purpose of this study is to determine numerically the effect of the geometry of the blades that form the runner on the efficiency of Michell-Banki Turbine (MBT). For this, two (2) geometries were studied corresponding to a circular sector of a standard tubular profile and an airfoil NACA 6512 modified in curvature profile and chord length, according to the profile of the standard tubular blade. For this study, transient simulations for multiphase water-air flow were implemented using a k-ε turbulence model in the Ansys 2020R1® CFX software. The two (2) turbine models were configured to the same hydraulic conditions of head and volumetric flow corresponding to 0.5 m and 16.27 L/s, respectively. Variations in rotational speed were configured between 100 and 200 RPM with 20 RPM steps. It was found that using the modified 6512 hydrodynamic profile, at 140 RPM increased efficiency by 6 %, compared to the conventional tubular type blade geometry
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Nag, Soumyadeep, Kwang Y. Lee, and D. Suchitra. "A Comparison of the Dynamic Performance of Conventional and Ternary Pumped Storage Hydro." Energies 12, no. 18 (September 12, 2019): 3513. http://dx.doi.org/10.3390/en12183513.
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With decreasing costs of renewable energy harvesting devices, penetration of solar panels and wind turbines have increased manifold. Under such high levels of penetration, coping with increased intermittency and unpredictability and maintaining power system resiliency under reduced inertia conditions has become a critical issue. Pumped storage hydro (PSH) is the most matured and economic form of storage that can serve the purpose of capacity for over 4 to 8 h. However, to increase network inertia and add required flexibility to low inertia power systems, significant paradigm shifting modifications have been engineered to result in the development of Ternary PSH (TPSH). In this paper a test system to consider governor interaction is constructed. The dynamic models of conventional PSH (CPSH) and TPSH are constructed and integrated to the test system to examine the effect of CPSH and TPSH in the hydraulic short circuit (TPSH-HSC). The ability and the effect of mode change (from pump to turbine) without the loss synchronism of TPSH has also been examined. Results display the superior capability and effect of TPSH with its HSC capability to contribute to frequency regulation during pumping mode and the effect of rapid mode change, as compared to its primitive alternative, CPSH.
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Magnoli, M. V., and J. Necker. "Simulation of pressure pulsations for pumped-storage units with wide operating range and comparison to experiments." IOP Conference Series: Earth and Environmental Science 1079, no. 1 (September 1, 2022): 012042. http://dx.doi.org/10.1088/1755-1315/1079/1/012042.
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Abstract The diversity of energy conversion sources in the current energy market increases the demand for stabilizing the electrical grid through ancillary services, frequency and power regulation from the facilities. Pumped-storage units with reversible pump-turbines or ternary sets constitute the currently most advanced solution for providing these services. This implies that pumped-storage units are required to operate in larger head and power ranges than before. In order to increase their flexibility in pump mode, variable speed units have been applied more frequently with additional challenges for the operating range in pump mode. The extension of the operating flexibility in pump mode makes use of a large portion of the model pump characteristic curve, especially in the case of variable speed units. Important challenges to the hydraulic development are among others the cavitation behaviour, hydraulic stability and pressure pulsation level. This study concentrates on the pressure pulsations in pump mode, which are of great relevance for the machine smooth operation. The pressure pulsations in a regulated radial reversible pump-turbine with low specific speed are numerically simulated with computational fluid dynamics (CFD) for several points along the complete operating range of the pump characteristic curve. The finite volume model includes the complete hydraulic machine from draft tube to spiral case and hybrid turbulence models were used, in this case scale adaptive simulation (SAS). The numerical simulation offers the possibility to assess different flow quantities at any point of the finite volume model, providing additional data to the experimental model test results. The integral quantities, e.g. head, flow and efficiency, were compared to the model test results to validate the numerical model. The simulated pressure pulsation amplitude and frequency were also compared to the measured pressure pulsations at the model at the available measuring locations in the spiral case, vaneless space and draft tube cone. After the validation, the computed flow fields were used to derive the pressure pulsation amplitude at other machine locations and components, e.g. at the runner.
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Domfeh, Martin Kyereh, Samuel Gyamfi, Mark Amo-Boateng, Robert Andoh, Eric Antwi Ofosu, and Gavin Tabor. "Numerical Simulation of an Air-Core Vortex and Its Suppression at an Intake Using OpenFOAM." Fluids 5, no. 4 (November 26, 2020): 221. http://dx.doi.org/10.3390/fluids5040221.
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A common challenge faced by engineers in the hydraulic industry is the formation of free surface vortices at pump and power intakes. This undesirable phenomenon which sometimes entrains air could result in several operational problems: noise, vibration, cavitation, surging, structural damage to turbines and pumps, energy losses, efficiency losses, etc. This paper investigates the numerical simulation of an experimentally observed air-core vortex at an intake using the LTSInterFoam solver in OpenFOAM. The solver uses local time-stepping integration. In simulating the air-core vortex, the standard k − ε, realizable k − ε, renormalization group (RNG) k − ε and the shear stress transport (SST) k − ω models were used. The free surface was modelled using the volume of fluid (VOF) model. The simulation was validated using a set of analytical models and experimental data. The SST k − ω model provided the best results compared to the other turbulence models. The study was extended to simulate the effect of installing an anti-vortex device on the formation of a free surface vortex. The LTSInterFoam solver proved to be a reliable solver for the steady state simulation of a free surface vortex in OpenFOAM.
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Arunachaleswaran, A., Muralidhar Madhusudan, A. Ramya, S. Elangovan, and M. Sundararaj. "Comparative Study of Ram Air Turbines based on Wind Tunnel Study for Specific Air Borne Energy Extraction." Defence Science Journal 71, no. 5 (September 2, 2021): 588–93. http://dx.doi.org/10.14429/dsj.71.16636.
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Ram Air Turbines (RAT) are used for emergency on-board power generation on aircraft and associated systems. Many studies on usage of RATs have shown promising results in terms of using RATs as a source of emergency on-board power generation. Many external podded systems on aircraft utilise RATs for self-sufficient adaptation. These pods generate their own power using RATs for their power requirements instead of depending on the mother aircraft power. Commercial cargo planes use RATs for generating emergency hydraulic power. A RAT was suggested to be used for emergency power, during failure of main alternator on a prototype aircraft. A specific requirement of the RAT was also to produce high drag for aerodynamic braking when deployed and concurrently generate electrical energy. Three models with different solidity were studied in wind tunnel at different wind speeds for suitability of this drag-energy combination. This paper presents the results of the study. Based on the results, a suitable RAT was selected for further analysis and ground trials.
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Amougou, Claude Boris, David Tsuanyo, Davide Fioriti, Joseph Kenfack, Abdoul Aziz, and Patrice Elé Abiama. "LCOE-Based Optimization for the Design of Small Run-of-River Hydropower Plants." Energies 15, no. 20 (October 12, 2022): 7507. http://dx.doi.org/10.3390/en15207507.
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Run-of-river hydropower plants are a cost-efficient technology that produce a power output proportional to the instantaneous flow of water diverted from the exploited stream by exploiting several mechanical, hydraulic, and electric devices. However, as no storage is available, its design and operation is tailored according to the unpredictability of its power generation. Hence, the modelling of this type of power plants is a necessity for the promotion of its development. Accordingly, based on models from the literature, this study proposes a comprehensive methodology for optimally designed small run-of-river hydropower plants based on a levelized cost of energy (LCOE). The proposed methodology aims at facilitating a faster design for more cost-effective and energy-efficient small hydropower plants. Depending on the average daily flow rates and the gross head of a given site, the model proposed in this study calculates the diameter, thickness, and length of a penstock; it also suggests the optimal selection of a turbine, determines the admissible suction head of a turbine for its optimal implementation, and determines the optimal number of turbines, all in order to minimize the LCOE of the proposed project. The model is tested to design a small run-of-river hydropower plant with a capacity of 6.32 MW exploiting the river Nyong in Mbalmayo. The results confirm the profitability of the investment with an LCOE of around 0.05 USD/kWh, which is the lowest limit value of the LCOE range for small hydropower plants, as presented in the IPCC (Intergovernmental Panel on Climate Change) report, assuming a project lifespan of 50 years and a discount rate of 12.5%. These results also show that it may be worth to provide the energy sector with a small hydropower design tool with a graphical interface. In addition, it would be appropriate to use a similar method in an off-grid context where a hydropower plant, with or without storage, is combined with another source to meet the electrical needs of a given population.
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Bukhtoyarov, Vladimir Viktorovich, and Vadim Sergeevich Tynchenko. "Design of Computational Models for Hydroturbine Units Based on a Nonparametric Regression Approach with Adaptation by Evolutionary Algorithms." Computation 9, no. 8 (July 28, 2021): 83. http://dx.doi.org/10.3390/computation9080083.
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This article deals with the problem of designing regression models for evaluating the parameters of the operation of complex technological equipment—hydroturbine units. A promising approach to the construction of regression models based on nonparametric Nadaraya–Watson kernel estimates is considered. A known problem in applying this approach is to determine the effective values of kernel-smoothing coefficients. Kernel-smoothing factors significantly impact the accuracy of the regression model, especially under conditions of variability of noise and parameters of samples in the input space of models. This fully corresponds to the characteristics of the problem of estimating the parameters of hydraulic turbines. We propose to use the evolutionary genetic algorithm with an addition in the form of a local-search stage to adjust the smoothing coefficients. This ensures the local convergence of the tuning procedure, which is important given the high sensitivity of the quality criterion of the nonparametric model. On a set of test problems, the results were obtained showing a reduction in the modeling error by 20% and 28% for the methods of adjusting the coefficients by the standard and hybrid genetic algorithms, respectively, in comparison with the case of an arbitrary choice of the values of such coefficients. For the task of estimating the parameters of the operation of a hydroturbine unit, a number of promising approaches to constructing regression models based on artificial neural networks, multidimensional adaptive splines, and an evolutionary method of genetic programming were included in the research. The proposed nonparametric approach with a hybrid smoothing coefficient tuning scheme was found to be most effective with a reduction in modeling error of about 5% compared with the best of the alternative approaches considered in the study, which, according to the results of numerical experiments, was the method of multivariate adaptive regression splines.
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Del Rio, A., E. Casartelli, L. Mangani, and D. Roos Launchbury. "Application of a Coupled Reynolds Stress Model to a Swirl-Driven Diffuser Flow." IOP Conference Series: Earth and Environmental Science 1079, no. 1 (September 1, 2022): 012068. http://dx.doi.org/10.1088/1755-1315/1079/1/012068.
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Abstract Swirling flow is a dominant feature in a significant number of technical applications. Hydraulic turbines at part-load are strongly affected by the related vortex rope phenomenon. Its dynamic behavior has a negative impact on the operating performance and durability of the machine. CFD can be used to get additional insight in this complex phenomenon but requires a valid simulation model able to capture the relevant flow physics, which is driven by highly anisotropic turbulent structures. The simulation results are therefore strongly affected by the turbulence modeling. A swirl apparatus (AC6-14), for which extensive experimental data is available, is used in this work for the assessment and validation of different turbulence models. The state-of-the-art SST k-ω model, with and without curvature correction, is compared to a coupled full Reynolds stress model. All models are integrated into a pressure-based coupled flow solver. The investigation revealed that both, SST k-ω with curvature correction and the full Reynolds stress model better predict the time-averaged velocity profiles in the diffuser compared to standard SST k-ω. The swirl component is thereby best captured with the Reynolds stress model. All models deliver a reasonable frequency spectrum for the dynamic behavior of the vortex rope. However, flow visualization shows that standard SST k-ω is not capable of predicting the shape and size of the vortex rope accordingly. Both, SST k-ω with curvature correction and the full Reynolds stress model, can be used in the future for more detailed flow investigations, which include also the assessment of flow control measures.
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Granyak, Valeriy. "MATHEMATICAL MODEL OF OVERHEAD PARAMETRIC EDDY CURRENT PRIMARY MEASURING TRANSDUCER OF ABSOLUTE MOVEMENT." Vibrations in engineering and technology, no. 2(97) (August 27, 2020): 123–28. http://dx.doi.org/10.37128/2306-8744-2020-2-13.
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To date, even in the developed countries of Europe, more than 50% of the power generating equipment of hydropower plants have worked their design life. In the CIS countries, the percentage of such equipment is even higher. The complete replacement of such equipment requires a large amount of investment, while a significant part of the latter has a satisfactory technical condition for the further extension of the service life. However, with an increase in the operating time of every electrical equipments, the probability of its failure inevitably increases, which can lead to significant material losses and to a significant danger to the life and health of the power plant personnel. Therefore, in view of the foregoing, monitoring and early diagnosis systems, which are entrusted with the protection function of both hydraulic turbines and auxiliary power equipment, are becoming increasingly relevant. One of the most promising methods of technical control and diagnostics of hydraulic units is the analysis of their vibro-acoustic characteristics. Including the axial component. However, a significant technical problem that arises in the construction of such systems is the limited use of known absolute vibration displacement sensors due to the lack of their high-precision mathematical models. In the article a mathematical model of an overhead parametric eddy current primary measuring transducer of absolute displacement has been developed. It is shown that both the effective value of the output current and the shift of its initial phase are found to be functionally dependent on the distance between the sensor and the conductive medium with a stable supply voltage. It has been established that, while ensuring acceptable overall dimensions, this sensor has sufficient sensitivity to convert the displacement to the effective (amplitude) value of the output current, which is constant in the range of movement from 0 to 5 mm, to ensure the required measurement accuracy.
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Ivarson, Mads Mehus, Chirag Trivedi, and Kaspar Vereide. "Investigations of Rake and Rib Structures in Sand Traps to Prevent Sediment Transport in Hydropower Plants." Energies 14, no. 13 (June 28, 2021): 3882. http://dx.doi.org/10.3390/en14133882.
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In order to increase the lifespan of hydraulic turbines in hydropower plants, it is necessary to minimize damages caused by sediment erosion. One solution is to reduce the amount of sediments by improving the design of sand trap. In the present work, the effects on sand trap efficiency by installing v-shaped rake structures for flow distribution and rib structures for sediment trapping is investigated numerically using the SAS–SST turbulence model. The v-shaped rake structures are located in the diffuser near the inlet of the sand trap, while the ribs cover a section of the bed in the downstream end. Three-dimensional models of the sand trap in Tonstad hydropower plant are created. The present study showed that integrating rib type structure can reduce the total weight of sediments escaping the sand trap by 24.5%, which leads to an improved sand trap efficiency. Consequently, the head loss in the sand trap is increased by 1.8%. By additionally including the v-shaped rakes, the total weight of sediments escaping the sand trap is instead increased by 48.5%, thus worsening the sand trap efficiency. This increases head loss by 12.7%. The results also show that turbulent flow commencing at the sand trap diffuser prevents the downstream settling of sediments with a diameter of less than one millimeter. The hydraulic representation of the numerical model is validated by comparison with particle image velocimetry measurements of the flow field from scale experiments and ADCP measurements from the prototype. The tested rib design has not previously been installed in a hydropower plant, and can be recommended. The tested v-shaped rakes have been installed in existing hydropower plants, but this practice should be reconsidered.
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Tkachuk, Mykola А., Andrey Grabovskiy, Mykola M. Tkachuk, Illia Klochkov, Mykola Prokopenko, Vladeslav Tretyak, and Iryna Voloshina. "THEORETICAL BASIS FOR ADVANCED SOLUTIONS OF HIGH RPM ELEMENTS OF CIVIL AND MILITARY MACHINES BASED ON STRENGTH AND DYNAMIC STABILITY CRITERIA." Bulletin of the National Technical University «KhPI» Series: Engineering and CAD, no. 1 (December 28, 2022): 79–84. http://dx.doi.org/10.20998/2079-0775.2022.1.08.
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In modern conditions, one of the significant obstacles to ensuring increased power, efficiency and resource of military and civilian vehicles is the exhausted possibilities of traditional technical solutions of basic elements and systems. This primarily applies to high-speed elements, in particular, turbines and rotary parts of air blowers of internal combustion engines, transmissions, drives, hydraulic machines and more. High speeds cause dynamic processes that can potentially lead to problems with strength, rigidity and stability. In order to substantiate the progressive technical solutions of high-speed parts, it is necessary to develop appropriate theoretical foundations for the analysis of processes that occur in these elements. The stress-strain state of the elements of rotor systems is of particular interest. It is also important to determine the stiffness properties of the elastic supports. In turn, this affects the stability of the rotor systems. This creates a basis for establishing patterns of influence of variable parameters on the characteristics of dynamic processes and states. A complex mathematical and numerical models of the stress-strain state and stability of motion of high-speed structural elements is developed on a unified methodological basis. These models are described by a common set of varied parameters. General criteria and restrictions are formulated. The search for advanced solutions is carried out by meeting certain complex criteria and constraints. Design parameters and operational modes are varied. The analysis problems are solved using a unified parametric model. Keywords: civil and military machines, RPM structural parts, stress-strain state, critical rotational velocity
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Zhang, Meng Sha, Zhong Ping Hua, Chen Shen, and Zhou Zhang. "The Parametric Modeling of Hydraulic Turbine Based on Pro/E Secondary Development." Applied Mechanics and Materials 577 (July 2014): 258–62. http://dx.doi.org/10.4028/www.scientific.net/amm.577.258.
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In this paper, combining with PRO/E4.0 software, getting the general design idea of the hydraulic turbine, and aiming at systematic analysis and research the key technologies of development design system process of hydraulic turbine. The key technologies include the pro/toolkit interface technology, menu design MFC dialog box as well as the establishment and access of database. Based on the two modes’ characteristics of PRO/TOOLKIT application, determining to use the DLL mode of the synchronous mode for the system design model's mode; Combining with the structure of the main parts of the hydraulic turbine, aiming at the characteristics of the pro/toolkit interface technology, menu design and MFC dialog box ,concluded the development processes of the pro/toolkit interface technology, menu design and MFC dialog box; Combining with the PRO/TOOLKIT interface technology and the characteristics of technology of MFC dialog box, selected the required software which is used to create and access database, and the specific development process. This provides important technical Supports for design system of Hydraulic turbine's development.
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D. Obozov, Alaybek, Ruslan A. Akparaliyev, Taalaybek T. Mederov, and Victor G. Krasnov. "Bi-rotor micro hydro power plant for energy supply to isolated consumers." International Journal of Engineering & Technology 7, no. 2.13 (April 15, 2018): 173. http://dx.doi.org/10.14419/ijet.v7i2.13.11682.
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This paper is dedicated to comparative analysis and description of a micro hydroelectric power plant with bi-rotor hydro generator. Based on the characteristics analysis, this paper describes a renewable energy source for a small watercourse; the feasibility of micro hydroelectric power plants with bi-rotor hydro generator is demonstrated. The features of their operation require in-depth research to substantiate parameters of such installations. This paper presents the analysis of the usage of micro hydroelectric solutions with bi-rotor hydro generator. The lattice theory problem was solved, which made it possible to determine the shape of the profile according to a given law of velocity distribution (pressure) on the contour. The experimental stand was developed, and the experiments were conducted to identify the dependence of the frequency of rotation from the flow and the dependence of the rotational frequencies of hydro turbines from various loads. Based on the results obtained, the optimum values of the rotational speed were identified. Presented results of experimental research are of significance and can be applied practically in design of micro hydroelectric power plants with bi-rotor hydro generator. Keywords: Bi-Rotor Hydro Generator; Differential Equation; Rotational Flows; Function; Hydraulic Models; Kinetic Energy; Renewable Energy Sources; Velocity Measurements. This paper is dedicated to comparative analysis and description of a micro hydroelectric power plant with bi-rotor hydro generator. Based on the characteristics analysis, this paper describes a renewable energy source for a small watercourse; the feasibility of micro hydroelectric power plants with bi-rotor hydro generator is demonstrated. The features of their operation require in-depth research to substantiate parameters of such installations. This paper presents the analysis of the usage of micro hydroelectric solutions with bi-rotor hydro generator. The lattice theory problem was solved, which made it possible to determine the shape of the profile according to a given law of velocity distribution (pressure) on the contour. The experimental stand was developed, and the experiments were conducted to identify the dependence of the frequency of rotation from the flow and the dependence of the rotational frequencies of hydro turbines from various loads. Based on the results obtained, the optimum values of the rotational speed were identified. Presented results of experimental research are of significance and can be applied practically in design of micro hydroelectric power plants with bi-rotor hydro generator.
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Simão, Mariana, Modesto Pérez-Sánchez, Armando Carravetta, and Helena Ramos. "Flow Conditions for PATs Operating in Parallel: Experimental and Numerical Analyses." Energies 12, no. 5 (March 8, 2019): 901. http://dx.doi.org/10.3390/en12050901.
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Micro-hydro systems can be used as a promising new source of renewable energy generation, requiring a low investment cost of hydraulic, mechanical, and electrical equipment. The improvement of the water management associated with the use of pumps working as turbines (PATs) is a real advantage when the availability of these machines is considered for a wide range of flow rates and heads. Parallel turbomachines can be used to optimize the flow management of the system. In the present study, experimental tests were performed in two equal PATs working in parallel and in single mode. These results were used to calibrate and validate the numerical simulations. The analysis of pressure variation and head losses was evaluated during steady state conditions using different numerical models (1D and 3D). From the 1D model, the installation curve of the system was able to be defined and used to calculate the operating point of the two PATs running in parallel. As for the computational fluid dynamics (CFD) model, intensive analysis was carried out to predict the PATs′ behavior under different flow conditions and to evaluate the different head losses detected within the impellers. The results show system performance differences between two units running in parallel against a single unit, providing a greater operational flow range. The performance in parallel design conditions show a peak efficiency with less shock losses within the impeller. Furthermore, by combining multiple PATs in parallel arrangement, a site’s efficiency increases, covering a wide range of applications from the minimum to the maximum flow rate. The simulated flow rates were in good agreement with the measured data, presenting an average error of 10%.
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Skripkin, S. G., D. A. Suslov, I. V. Litvinov, E. U. Gorelikov, M. A. Tsoy, and S. I. Shtork. "Comparative analysis of air and water flows in simplified hydraulic turbine models." Journal of Physics: Conference Series 2150, no. 1 (January 1, 2022): 012001. http://dx.doi.org/10.1088/1742-6596/2150/1/012001.
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Abstract This article presents a comparative analysis of flow characteristics behind a hydraulic turbine runner in air and water. Swirling flow with a precessing vortex core (PVC) was investigated using a laser Doppler anemometer and pressure pulsation sensors. The experiments were conducted on aerodynamic and hydrodynamic test rigs over a wide range of hydraulic turbine operating conditions. Part-load modes of hydraulic turbine operation were investigated using the Fourier transform of pressure pulsations obtained from acoustic sensors. The features of the swirling flow were shown for the range of operating conditions from deep partl-load to overload.
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Working Group Prime Mover and Energy Supply. "Hydraulic turbine and turbine control models for system dynamic studies." IEEE Transactions on Power Systems 7, no. 1 (February 1992): 167–79. http://dx.doi.org/10.1109/59.141700.
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Shi, Feng Xia, Jun Hu Yang, and Xiao Hui Wang. "Analysis of Off-Design Flow Field and Prediction of Performance in Hydraulic Turbine." Applied Mechanics and Materials 496-500 (January 2014): 877–80. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.877.
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Two models of hydraulic turbine based on pump in reversal were simulated. Pressure distribution of flow field in Variable conditions was analysed and external characteristic was forecasted for hydraulic turbine. It was shown: the head increased with flow increased, with increasing of flow rate, efficiency first increased and then decreased. Compared with the turbine with a guide vane, the head of two models was almost equal, but the disparity of efficiency was large, and the efficiency of hydraulic turbine with a guide vane above on the efficiency of hydraulic turbine without guide vane. Pressure pulsation was existent in runner inlet. From runner inlet to runner outlet, the pressure distributed evenly from high to low. Added with a guide vane, the pressure distribution was more evenly than before and the Amplitude of pressure fluctuation decreased.
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Yurchenko, G. G. "Gas-turbine engine secondary air system analysis." Izvestiya MGTU MAMI 9, no. 3-4 (August 10, 2015): 46–54. http://dx.doi.org/10.17816/2074-0530-67107.
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Secondary air system model based on graph theory and one dimentional hydraulic models is discussed. Channel inclination to major axis of integration is taking into account. New hydraulic channel model for smooth transition between “horizontal” and “vertical” flow passages is proposed. Commercial software for 2D and 3D flow modeling were used for one dimentional models verification.
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Vournas, C. D. "Second order hydraulic turbine models for multimachine stability studies." IEEE Transactions on Energy Conversion 5, no. 2 (June 1990): 239–44. http://dx.doi.org/10.1109/60.107216.
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