Dissertations / Theses: 'Francis-Turbine'

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Bergmann-Paulsen, Jonas. "FSI-analysis of a Francis turbine." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19081.

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Sediment erosion in Francis turbines is a big problem in hydropower plants in and around the Himalayas. The sediment composition in the rivers contains high levels of the hard mineral quarts. When the sediments enter the turbine they cause erosive damage to exposed parts such as covers, guide vanes and runner. The sediment concentration is at its highest during the monsoon period. During this period some turbines are stopped when the sediment consentration reaches certain levels to reduce the damage. Jhimruk power plant in the mid-western part of Nepal is a good example of how the sediment erosion affects the operation of a power plant. During the monsoon period the turbines can be eroded to an almost unrepairable state. The turbines have to go through substantial annually maintenance. A result of this is reduced power output and high maintenance costs. It is therefore of interest to design a new Francis turbine that can better withstand the sediment erosion. A cooperation project between Kathmandu University and The Norwegian University of Science and Technology was started as a part of the RenewableNepal project which aims to develop and start manufacturing of erosion resistant Francis turbines.A parameter study of different blade designs have been performed to find a more erosion resistant design. In this thesis FSI analyses have been performed on three different designs to verify their structural integrity. The designs transfers the hydraulic energy from the water to the blade in different sections. The results showed a stress distribution which coincided with the energy transfer along the blade. The reference design was analyzed with two different blade thickness. For all the designs the stress was relatively low compared to the criteria for hydraulic turbines.

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Alnaga, Ahmed. "Conception optimale du tracé hydraulique des turbines Francis." Grenoble INPG, 2006. http://www.theses.fr/2006INPG0163.

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Devant le nombre de degré de liberté disponible dans le choix d'une nouvelle conception d'une turbomachine ou dans l'amélioration d'une machine existante. Il est aujourd'hui nécessaire de développer des techniques de conception et d'optimisation à base d'outils mathématiques permettant l'intégration efficace des méthodes et outils développées dans le dimensionnement et l'analyse des écoulements internes. Ces techniques permettent alors la recherche des meilleurs compromis conduisant à une conception optimisée. Mon travail recherche m'a permis de mettre au point une technique de tracé et d'optimisation de la géométrie des turbines FRANCIS. Cette technique est basée sur une paramétrisation géométrique de tous les éléments de la turbine (bâche avant-distributeur, directrices, roue et aspirateur). L'écoulement est ensuite estimé avec des logiciels de CFD et une fonction objectif définie à partir des performances recherchée pour la machine est évaluée à partir de l'écoulement calculé. Cette fonction objectif est donc une fonction non linéaire des paramètres qui ont servis à paramétriser la géométrie. Son optimisation est alors possible en utilisant, par exemple des algorithmes génétiques. Pour mettre en œuvre une telle optimisation, il est nécessaire d'automatiser l'ensemble du processus grâce à des scripts informatiques, pour construire la géométrie de la turbine à partir des paramètres, puis un maillage robuste des domaines de calcul. Le calcul CFD, avec le post-processing qui permet d'estimer la fonction objectif, sont ensuite exécutés automatiquement pour compléter un cycle de calcul. J'ai mis au point une telle technique d'optimisation pour toute la partie "haute pression" de la turbine. Pour la roue, une technique "manuelle" d'optimisation, beaucoup plus rapide que l'automatique, a été utilisée (5 à 10 itérations à comparer avec 150 à 200 calculs pour la méthode automatique)
Because of the higher number of parameters available in the choice of a new design of a turbomachinery or in the improvement of an existing machine. It is today necessary to develop techniques of design and optimization based on mathematical tools allowing the effective integration of the methods and tools developed in dimensioning and in the analysis of the internal flows. These techniques then allow the research of the best compromises leading to an optimized design. My research work enabled me to develop a technique of design and optimization of FRANCIS turbines. This technique is based on a geometry parameterization of ail the elements of the turbine (Spiral-Casing, distributor, runner and draft tube). The flow is then estimated with software of CFD and a function objective defined starting from the performances sought for the machine is evaluated starting from the calculated flow. This function objective is thus a nonlinear function of the parameters which were used for geometry parametrization. Its optimization is then possible while using, for example genetic algorithms. To make an optimization, it is necessary to automate the whole of the process thanks to data-processing scripts, to build the geometry of the turbine starting from the parameters, with a robust grid for the domain calculations, Then Calculation CFD, with the postprocessing which makes it possible to estimate the function objective, are then carried out automatically to supplement a cycle of calculation. I developed such a technique of optimization for ail the part "high pressure" of the turbine. For the runner, a "manual" technique of optimization, much faster than the automatic, was used (5 to 10 iterations to be compared with 150 to 200 calculations for the automatic method). This technique was tested successfully for two examples of turbine Francis, one at slow specific speed (nq=48), the other rapid (nq=81)

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Gjøsæter, Kristine. "Hydraulic Design of Francis Turbine Exposed to Sediment Erosion." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14256.

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Sediment erosion is a large problem for turbines operated in sand laden water, especially in the Himalayas and the Andes Mountains, where the contents of hard minerals in the rivers are high. A program called <i>RenewableNepal</i> supports the development of a new design philosophy for hydraulic turbines. NTNU and Kathmandu University cooperate within this program, and this master thesis is part of that cooperation.The objective of this thesis is to carry out the hydraulic design of a Francis turbine with reduced velocities. As part of that, a design software has been developed, using Matlab as programming tool. This software has been used to generate a reference design with the same physical dimensions as for the existing runners at Jhimruk Hydrorelectric Centre in Nepal. CFD analysis has been performed to verify the design software output, showing good results. Analysis of erosion from CFD were not successful as mesh independency for the analysis could not be established. Hence results for erosion prediction from CFD studies has not been presented in this thesis.A parametric study has been carried out, varying either the outlet diameter, the number of pole pairs, the inlet velocity, the acceleration of the flow through the runner, the height of the shroud or the blade angle distribution. An erosion model was implemented in the design software, and used as a control variable for the parametric study. CFD analyses using Ansys CFX were performed for selected designs with lower erosion than the reference design. The largest reduction of erosion was obtained when increasing the number of pole pairs, which implies that the rotational speed of the turbine is decreased. This does however increase the size of both the turbine and the generator, which cause increased investment costs as well. CFD analysis shows that the hydraulic efficiency for this design is higher than for the reference design. It was also discovered that by changing the blade angle distribution, and consequently also the energy distribution, a substantial reduction of erosion was possible without changing the physical dimensions or the rotational speed of the turbine. The efficiency for this design is also higher than for the reference design. The most promising design was found as a combination of these two effects, giving a reduction of the erosion of 50 percent compared to the reference design. CFD analysis for this design show a good efficiency and acceptable flow conditions in the runner. This and other designs with the modified blade angle distribution will have an unconventional energy conversion through the runner, leading to larger hydraulic forces on the trailing edge of the blades. Strength analyses of the blade would be beneficial, but have not been performed.The main focus in this thesis has been on developing the design software and developing runner designs for reducing sediment erosion. There have been no attempts for optimizing the designs of the guide vanes and stay vanes due to time constraints.

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Gogstad, Peter Joachim. "Hydraulic design of Francis turbine exposed to sediment erosion." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16772.

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High concentrations of sediments is a serious problem for hydropower stations in the Himalayas and the Andes Mountains. For run-of-river power plants sediment causes heavy erosion even with settling basins. This leads to reduced operating hours and high maintenance cost. In addition, the original design experienced problem with heavy cavitation.The objective of this master thesis is to carry out new hydraulic design of the runner and guide vanes of the existing Francis turbines in La Higuera Power Plant with reduced velocity components. To achieve this the cause of the heavy cavitation, which made the turbine fail, has to be established.Results from numerical simulations indicates a low pressure zone causing heavy leading edge cavitation is the reason for the turbine failure. The off-design operation has made the cavitation even worse.To carry out a new design, the in-house design software Khoj was used. Some new parameters, like blade leaning, were included in the program. Blade leaning is an important tool for pressure balancing the runner blade. Further, a parameter study was carried out to investigate the effect of blade leaning, blade angle distribution and blade length. The numerical simulation indicates proper pressure balancing could have avoided the cavitation problems and a new design should have an X-blade shape. Because the power plant is already built, the number of variables is limited. The rotational speed, inlet and outlet diameter remained constant. This made it impossible to significantly reduce the relative velocities. Therefore, coating of all wet surfaces is proposed to reduce the effect of erosion.The main objective for this thesis has been to identify the cause of the turbine failure and develop a new design to fit in the existing power plant. Complete 3D-drawings of the design, including runner and guide vanes, has not been made due to lack of time.

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Chitrakar, Sailesh. "FSI analysis of Francis turbines exposed to sediment erosion." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133298.

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Sediment erosion is one of the key challenges in hydraulic turbines from a design and maintenanceperspective in Himalayas and Andes. Past research works have shown that the optimization of theFrancis turbine runner blade shapes can decrease erosion by a signicant amount. This study conductedas a Master's Thesis has taken the proposed designs from past works and conducted a CFDanalysis on a single passage of a Francis runner blade to choose an optimized design in terms of erosionand eciency. Structural analyses have been performed on the selected design through one-way andtwo-way FSI to compare the structural integrity of the designs.Two types of cases have been considered in this thesis work to dene the boundary condition of thestructural model. In the rst case, a runner blade is considered to have no in uence of the joint andother stier components. In the second case, a sector of the whole runner has been modeled withnecessary boundary conditions. Both one-way and two-way FSI have been performed on the casesfor the designs. Mesh independent studies have been performed for the designs, but only for the rstcase, whereas in the second case, a ne mesh has been used to make the analysis appropriate.The loads have been imported into the structural domain from the uid on the interfaces for one-wayFSI. In the case of two-way FSI, the Multi-Field Solver (MFX) supported by ANSYS has been usedto solve the coupled eld analysis. A fully coupled FSI in ANSYS works by writing an input le inthe structural solver containing the information about the interfaces in the structural domain, whichis imported in the uid solver. The interaction between the two domains is dened in ANSYS-CFX,including the mesh deformation and solver setups. The results have been post-processed in CFX-Post,where the results from both the elds are included. It has been found that the structural integrity ofthe optimized design is better than the reference design in terms of the maximum stress induced inthe runner. The two-way FSI analysis has been found as an inevitable part of the numerical analysis.However, with the advancement of the computational capability in the future, there could be a greatscope in the research eld to carry out a fully-coupled transient simulation for the whole runner toget a more accurate solution.

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Pham, Thi Kim Loan. "Modélisation du comportement d'une roue de turbine francis au régime d'emballement." Grenoble INPG, 2002. http://www.theses.fr/2002INPG0009.

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Arpe, Alca Jorge Alejandro Arpe Jorge. "Analyse du champ de pression pariétale d'un diffuseur coudé de turbine Francis /." [S.l.] : [s.n.], 2003. http://library.epfl.ch/theses/?display=detail&nr=2779.

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Okyay, Gizem. "Utilization Of Cfd Tools In The Design Process Of A Francis Turbine." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612452/index.pdf.

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Francis type turbines are commonly used in hydropower generation. Main components of the turbine are spiral case, stay vanes, guide vanes, turbine runner and the draft tube. The dimensions of these parts are dependent mainly on the design discharge, head and the speed of the rotor of the generators. In this study, a methodology is developed for parametric optimization by incorporating Matlab codes developed and commercial Computational Fluid Dynamics (CFD) codes into the design process. The design process starts with the selection of initial dimensions from experience curves, iterates to improve the overall hydraulic efficiency and obtain the detailed description of the final geometry for manufacturing with complete visualization of the computed flow field. A Francis turbine designed by the procedure developed has been manufactured and installed for energy production.

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Tørklep, Anders Mathias. "Pressure oscillations during start and stop of a high head Francis turbine." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19323.

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Start and stop procedures affect pressure oscillations throughout a hydropower plant. A desire to study how pressure oscillations behave during these dynamic conditions was the basis of this report. Instrumentation, experimentation and measurement analysis was conducted on a Francis model turbine in the Waterpower Laboratory at NTNU. Eight pressure transducers were calibrated and used during the experiments. Two transducers were installed in the draft tube below the turbine. One was placed in the vaneless space between the guide vanes and the impeller vanes. Three pressure transducers on an impeller vane and two transducers located at the inlet were also included in the experiments. Frequency analysis (PSD) was carried out for all the measurements to explore various pressure oscillations. Except for the low frequent oscillations (< 30 Hz), definite frequencies repeatedly dominated the frequency domain during start/stop as well as for steady state operation. The impeller vane oscillation showed an increase in pressure amplitude during guide vane closing. A bigger amplitude increase was registered for BEP than for part load and full load operation. The guide vane frequency was located in and only in the runner. The amplitude of the guide vane frequency was significant and was located for all studied operational points. The power of this oscillation decreased during guide vane closing. One specific frequency arose the question of an overtone phenomenon for the water hammer oscillation, a phenomenon, were the fundamental frequency is three times higher than the customary water hammer frequency.

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Meland, Hallvard. "A new Design of a Francis Turbine in order to reduce Sediment Erosion." Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10161.

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This Master Thesis is about the sand erosion challenges with the Francis turbines. The background for studying this subject is the fact that the sand erosion problem is a very negative factor for the development of new hydro electric power plants in many developing countries. The target with this Master Thesis has been to develop a new design, a revised version of the Francis turbine, reducing the sand erosion by 30- 50 per cent compared with today´s version of turbines. The present version of Francis turbines is consisting of three different vane cascades, The stay, guide and runner cascade. The sand erosion is in proportion with the relative speed between the sand particles and the steel cubed. This challenge has thus been analyzed and solved by reducing this speed through the turbine. Regarding the stay vanes, a new design has been proposed where the stay vanes are pressing the spiral casing from outside and not from the inside. This will result in the fact that the whole sand erosion problem has been removed. It has been proposed to remove the the guide vane cascade. This will consequently remove the sand erosion problem here as well. A favourable solution is to increase the reaction degree. For the runner a study of four different parameters has been carried out. These parameters were the number of pole pair in the generator, outlet angle, reaction degree and UCu distribution. The analysis shows that a reduction of sand erosion at the runner outlet was possible by selecting a higher number of pole pair along with a higher outlet angle than what is standard practice today. This result is of high significant importance since the sand erosion is biggest at the runner outlet. A change in the reaction degree may enable the erosion at the inlet of the runner, whereas a change in the UcU will change the erosion between the inlet and outlet. By selecting favourable parameter values, a substantial reduction of sand erosion in a Francis turbine will be possible. The turbines in this Master thesis have been designed in the computer program Matlab. A proposal for new design based upon the results of the parameter study has been analyzed in a CDF analysis. This analysis has been made in Ansys CFX.

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Goyal, Rahul. "FLOW FIELD IN A HIGH HEAD FRANCIS TURBINE DRAFT TUBE DURING TRANSIENT OPERATIONS." Doctoral thesis, Luleå tekniska universitet, Strömningslära och experimentell mekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-66297.

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Hydroelectricity plays an important role to balance the stability of grid network. In order to improve the stability of presently high loaded grids, hydropower plants are being operated over a wide range of operations and experiencing frequent start-stop, load rejection, and load acceptance. The turbines need to sustain sudden change in their operating condition to balance the grid frequency. Francis turbines have been widely used because of their wider operating range and higher stability in operation during rapid load variation. This has resulted in severe damage to the turbines as they are not normally designed to operate under such transient conditions. Several low and high frequency pressure fluctuations prevail during transients operating conditions. Generally, wall pressure measurements are performed which may not provide sufficient information to investigate the flow instabilities related to these fluctuations. Thus, the main objective of the present work is to simplify and perform optical measurements in a turbine during transient operating conditions to investigate the flow field. The measurements have been performed at the Water Power Laboratory using a high head model Francis turbine. The turbine is a 1:5.1 scale down model of a prototype operating at the Tokke Power Plant, Norway. The model runner diameter, net head, and discharge at the best efficiency point (BEP) were 0.349 m, 12 m, and 0.2 m3 s-1, respectively. A total ten pressure sensors were mounted at different locations namely, turbine inlet, vaneless space, and draft tube. The data were acquired at a sampling rate of 5 kHz. The instruments and sensors have been calibrated according to guidelines available in IEC standards. The determined total uncertainty in the measurement of hydraulic efficiency was ±0.15% at BEP condition. The velocity measurements in the draft tube cone were performed using a 2D PIV system and the images were sampled at a rate of 40 Hz. Steady state measurements were carried out considering the realistic design and off-design operating conditions of the prototype turbine. Therefore, the angular speed of the runner was maintained constant for all steady state conditions during the measurements. The maximum hydraulic efficiency (92.4%) was observed at nED = 0.18, QED = 0.15, and a = 9.8º, which is named BEP. It is observed that the turbine experiences significant pressure fluctuations at the vaneless space, runner, and the draft tube. The fluctuations due to rotor-stator interaction (RSI) were observed to be most dominating at high load condition, however, fluctuations due to the rotating vortex rope (RVR) at part load (PL) condition. Two different modes (synchronous and asynchronous) modes of vortex rope are observed at PL condition of the turbine. An asymmetry in the flow leaving the runner was detected at both design and off-design conditions, with a stronger effect during off-design operating condition. Numerical simulations of the model turbine were carried out at PL operating condition. The simulations were performed using two turbulence models, standard k-ε and SST k-ω, with high-resolution advection scheme. The numerical pressure values obtained with both standard k-ε model and SST k-ω showed a small difference with the experimental values. The amplitudes of numerical pressure values were higher (~2.8%) in the vaneless space and lower (~5.0%) in the draft tube than the experimental values. The frequencies of the RSI and RVR were well captured in the turbine but the amplitudes were overestimated. During load rejection from BEP to PL, the plunging mode of the vortex rope was observed to appear first in the system than that of the rotating mode. Whereas during the load acceptance from PL to BEP, both the modes were observed to disappear simultaneously from the system. In the velocity data, the axial velocity only contributed to the development of the plunging mode and radial velocity to the rotating mode. The region of low velocity, stagnation point, flow separation, recirculation, oscillating flow and high axial velocity gradients were well captured in the system during the transients. The induced high-velocity gradients during the load acceptance from BEP to HL was observed to develop a vortex core in the draft tube. During startup and shutdown, the guide vanes angular position was moved from one to another steady state condition to achieve the minimum load condition of the turbine. At this condition, the generator of the turbine was magnetized at the synchronous speed during startup and shutdown, respectively. The frequency of wave propagation was observed to vary with the runner angular speed during startup and complete shutdown of the turbine. Comparatively high-pressure fluctuations in the draft tube were observed during the guide vane movement from the high discharge conditions. Some unsteady phenomena such as the formation of dead velocity zone, backward flow, and flow oscillations were observed during startup and shutdown of the turbine. The current work has been also used to continue a series of workshops, i.e., Francis-99. The first workshop was held on December 2014 with the cooperation of LTU and NTNU. The measurements performed in this work were used for the second workshop which was held on December 2016. The investigations presented in this thesis will be further explored in the third workshop scheduled for December 2018.

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Khalfi, Boubaker. "Contribution au développement d'un code de calcul des contraintes dans une turbine francis /." Thèse, Montréal : École de technologie supérieure, 2005. http://wwwlib.umi.com/cr/etsmtl/fullcit?pMR11527.

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Thèse (M. Ing.)--École de technologie supérieure, Montréal, 2005.
"Mémoire de maîtrise présenté à l'École de technologie supérieure comme exigence partielle à l'obtention de la maîtrise en génie mécanique." Bibliogr.: f. [126]-127. Également disponible en version électronique.

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Khalfi, Boubaker. "Contribution au développement d'un code de calcul des contraintes dans une turbine francis." Mémoire, École de technologie supérieure, 2005. http://espace.etsmtl.ca/367/1/KHALFI_Boubaker.pdf.

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La conception des turbines hydrauliques nécessite des outils rapides et efficaces pour accélérer le processus de fabrication de la turbine, surtout lorsqu'il s'agit d'un marché tellement compétitif qu'on ne peut tolérer aucun défaut. Parmi les parties de turbine qui nécessitent plus d'attention: le joint aube plafond. L'objectif est de contribuer au développement d'un outil rapide qui permet une vérification des caractéristiques mécaniques à ce niveau (joint aube plafond) lors de la conception hydraulique d'une turbine Francis. Cet outil pourra servir par la suite à la conception du joint aube plafond, ainsi qu'à la définition de la forme du plafond.

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Castrataro, Albert. "Mesure et prédiction des contraintes résiduelles dans une turbine hydraulique de type Francis." Mémoire, École de technologie supérieure, 2006. http://espace.etsmtl.ca/542/1/CASTRATARO_Albert.pdf.

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Le soudage en multipasse est une technique d'assemblage fortement répandue dans la fabrication de turbines hydrauliques de type Francis faites d'acier inoxydable CA-6NM. Les fortes températures provoquent des déformations et des contraintes résiduelles qui peuvent avoir de graves conséquences sur la durée de vie des turbines. Ce phénomène est très peu documenté dans la littérature scientifique. La présente étude tentera de suivre l'évolution et de prédire la distribution de contraintes résiduelles et son intensité maximale au niveau des joints soudés d'une turbine. Les étapes de mise en oeuvre de l'étude sont les suivantes: premièrement des données expérimentales ont été recueillies pour connaître l'intensité de la contrainte résiduelle sur des échantillons d'acier doux et d'acier inoxydable martensitique au niveau d'un joint soudé. Deuxièmement une méthode numérique a été développée, basée sur une formule proposée par la norme ASM pour prédire l'intensité maximale au niveau d'un joint soudé à partir de mesures expérimentales sur un échantillon d'acier doux. Par la suite une relation mathématique et une méthode numérique ont été développés pour prédire la contrainte maximale dans un échantillon d'acier inoxydable martensitique de type 415. Les résultats expérimentaux sur échantillon d'acier doux ont permis de mesurer une intensité maximale de 220 MPa en tension au centre du cordon de soudure. Alors que l'intensité maximale de l'échantillon d'acier inoxydable martensitique est de 341 MPa en compression dans le joint. Les méthodes numériques développées dans cette étude ont permis de prédire l'intensité maximale de la contrainte avec une marge d'erreur de l'ordre de 12 et 9% pour les échantillons d'acier doux et d'acier inoxydable martensitique respectivement. L'approche expérimentale consiste à suivre l'évolution des contraintes pendant un cycle complet de fabrication d'une turbine. Des mesures par jauges de déformations ont été prises entre les différentes phases de fabrication, soient l'usinage, la soudure et le traitement thermique. De plus des mesures en continu ont été enregistrées pour suivre les variations de températures et de contraintes pendant le soudage. Globalement les mesures prises sur la turbine ont permis d'établir le niveau de contrainte moyen à 155 MPa, mesuré en tension, après usinage des aubes. Les mesures en continu durant le soudage ont donné une variation de 47 MPa en tension. On a constaté que le niveau de contrainte a augmenté proportionnellement avec la température pendant le soudage. Par ailleurs, lors de la soudure, lorsque la température locale de la turbine diminuait, les contraintes ne suivaient pas la même évolution que la température. L'hypothèse de l'effet de bridage a été amenée. Durant le traitement thermique, une relaxation de 169 MPa a pu être mesurée, alors que le niveau de contrainte final se situe entre 33 et 51 MPa, en compression sur l'extrados de l'aube à sa sortie. On remarque que le niveau de contrainte final n'est pas nul. Par contre, les contraintes de compression sont bénéfiques aux endroits sollicités en tension. Finalement la méthode numérique développée pour les aciers inoxydables martensitiques n'a pu être vérifiée pour faire la prédiction de la contrainte maximale dans un joint soudé d'une turbine faite d'acier. CA-6NM par manque de données expérimentales.

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Bergan, Carl Werdelin. "Transient LDV-measurements in the draft tube of a high head Francis turbine." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26064.

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Francis-99 is a series of upcoming workshops aimed at determining the state of the art of high head Francis turbine simulations. The scope of this essay is to provide empirical data to serve as validation for the CFD simulations.Axial and tangential velocity profiles were measured for a model of the Tokke runner while operating in part load, best efficiency, and full load, at two different locations in the draft tube cone: 64mm and 382mm below the draft tube inlet. The results were phase resolved in order to calculate normal Reynolds stresses at the different operating conditions, and the results have been compared with computer simulations. The resulting velocity profiles have been evaluated with respect to the governing equations, and the correlation between velocity profiles, pressure gradients and normal stresses has been discussed. The effect of head on the velocity profiles has been evaluated, and found to have only a small impact on the reduced velocity profiles, both axially and tangentially. The repeatability of the test rig was also tested, and found to be within acceptable limits.The reliability of the measured velocity profiles is considered high enough to be admissible as validation data for the Francis-99 workshop.The simulated results show good agreement with the measured velocity profiles for axial flow, but show great discrepancies for the tangential velocity profiles. How- ever, some similarities can be seen between the simulated and measured results, and further work is required in this area.

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Heschung, Marine. "Investigation sur le débalancement de l'écoulement observé expérimentalement sous la roue d'une turbine Francis." Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27855.

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Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2017-2018
Ce mémoire vise à contribuer à l'amélioration de la prédiction numérique des performances d'une turbine hydraulique par la quantification de l'impact de certains paramètres d'influence, autant physiques que méthodologiques. Pour ce faire, l'écoulement dans une turbine caractérisée par une chute de rendement près du meilleur point de fonctionnement a été étudié. Cette dernière est associée à une baisse abrupte du coefficient de récupération de l'aspirateur, une composante connue pour jouer un rôle capital dans les performances globales de la machine. L'accent a particulièrement été mis sur l'étude du débalancement de l'écoulement sous la roue, observé à la suite d'une campagne de mesure expérimentale effectuée sur le banc d'essai du CREMHyG à Grenoble. En effet, l'écoulement en sortie de roue est souvent considéré axisymétrique dans les simulations numériques, une simplification qui est en désaccord avec les données expérimentales du cas étudié dans ce projet de recherche. Afin d'identifier la nature du débalancement, une analyse critique a été menée sur les données expérimentales. Toutefois, aucune conclusion satisfaisante n'a pu être tirée puisqu'une inconsistance entre les données obtenues par LDV et celles obtenues par PIV a été décelée. Considéré statique, il a été démontré que la présence d'un tel débalancement à l'entrée de l'aspirateur altère considérablement la topologie de l'écoulement en aval ainsi que la prédiction des performances. De plus, certains aspects des simulations obtenus avec ce type de débalancement ne concordent pas avec les observations expérimentales, c'est notamment le cas pour la zone d'amorçage du décollement mais aussi pour l'écart de débit entre les deux pertuis. Il a également été montré que les simulations des composantes fixes en amont de l'aspirateur, incluant une importante partie de la conduite d'amenée, ne permettent pas de retrouver l'asymétrie de l'écoulement observée expérimentalement en sortie de roue. En effet, l'écoulement secondaire, associé à la présence d'une conduite coudée en amont de la bâche spirale, s'est avéré avoir très peu d'influence sur la distribution de l'écoulement dans l'avant-distributeur et dans le distributeur. La conduite menant jusqu'à l'entrée de la bâche spirale semble être assez longue pour que les modifications apportées au profil de vitesse deviennent insuffisantes pour perturber l'écoulement à cet endroit.
This master degree thesis aims at enhancing the numerical prediction of the performance of a hydraulic turbine by quantifying the impact of physical and methodological influencing parameters. To this end, the flow in a turbine characterised by an efficiency drop near the best efficiency point was studied. The latter is associated with a sharp drop in the recovery coefficient of the draft tube, a component known to play a key role in the global performance of the machine. Particular emphasis was placed on the study of the imbalance of the flow at the runner exit, observed following an experimental measurement campaign carried out on the CREMHyG test bench in Grenoble. Indeed, the flow at the runner exit is often considered axisymetric in numerical simulations, a simplification that is not consistent with the experimental data of the case studied in this research project. In order to identify the nature of the imbalance, a critical analysis was conducted on the experimental data. However, no satisfactory conclusion could be drawn since inconsistency between the data obtained by LDV and those obtained by PIV was identified. Considered static, it has been shown that the presence of such an imbalance at the inlet of the draft tube alters considerably the topology of the downstream flow as well as the prediction of the performances. Moreover, some aspects of the simulations obtained with this type of imbalance do not agree with the experimental observations, it is notably the case for the initiation zone of the flow detachment but also for the flow rate imbalance between the two draft tube channels. It has also been shown that the numerical simulations of fixed components upstream of the draft tube, including a large part of the penstock, do not allow to recover the asymmetry of the flow experimentally observed at the exit of the runner. Indeed, the secondary flow, associated with the presence of a bend upstream of the spiral case, proved to have a very little influence on the distribution of the flow in the distributor. The pipe leading to the entrance of the spiral case appears to be long enough for changes made in the velocity profile to become insufficient to disrupt the flow at this place.

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Wack, Jonas [Verfasser], and Stefan [Akademischer Betreuer] Riedelbauch. "Numerical investigation of the full load instability in a Francis turbine / Jonas Wack ; Betreuer: Stefan Riedelbauch." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1223928942/34.

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Joy, Jesline. "Mitigation of Pressure Pulsations in Francis Turbine Draft Tube with a GuideVane System : A Numerical Investigation." Licentiate thesis, Luleå tekniska universitet, Strömningslära och experimentell mekanik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-83990.

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The use of renewable energy such as water and wind to produce electricity has been proven extremely effective in Sweden. The ability of these renewable resources to produce clean output energy counters the adversities caused by non-renewable resources. The use of hydraulic turbines is a good example of favoured technique for energy and power production using renewable resources. The hydro-turbines are designed to operate at best efficiency point (BEP). Varying energy demands in recent years implies on the need of flexible operation of hydraulic turbines. The issue of pressure pulsations in the draft tube of hydro-turbines, observed at lower operating conditions has been unresolved for many years. These pressure pulsations are related to the ‘rotating vortex rope’ (RVR) observed at part load operation and, affects the lifespan and performance of the hydro-turbine adversely. Several techniques have been investigated in the past to reduce the pressure pulsations in the draft tube at part load operation and enhance the flexibility of the turbine. During the present research study, a passive flow control technique was investigated numerically by implementing a guide vane system in the draft tube of the Francis-99model turbine. Guide vanes are mechanical devices that can direct the flow in a desired direction. The current study presents the possibility of reducing the pressure pulsations in the draft tube by mitigating the RVR using a guide vane system in the draft tube. At the initial stages of the research study, a reduced numerical model of the Francis model turbine was developed by only considering the draft tube domain. The motive was to develop a reduced model to perform the parametric analysis for the guide vane system in the draft tube with reduced computational time, power, and storage. The results obtained from the numerical study were found to be in good agreement with theFrancis-99 semi-model with passage domains. A parametric study was performed to achieve a guide vane system design that could mitigate RVR with minimum losses. During this study, the number of guide vanes, the chord and the span of the guide vanes were investigated. It was found that a set of three guide vane system with chord of 86% of runner radius and leading-edge span of 30% of runner radius is an ideal design that mitigates RVR above 95%.

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Brugière, Olivier. "Fiabilité et évaluation des incertitudes pour la simulation numérique de la turbulence : application aux machines hydrauliques." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENI002/document.

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La simulation numérique fiable des performances de turbines hydrauliques suppose : i) de pouvoir inclure dans les calculs RANS (Reynolds-Averaged Navier-Stokes) traditionnellement mis en œuvre l'effet des incertitudes qui existent en pratique sur les conditions d'entrée de l'écoulement; ii) de pouvoir faire appel à une stratégie de type SGE (Simulation des Grandes Echelles) pour améliorer la description des effets de la turbulence lorsque des écarts subsistent entre calculs RANS et résultats d'essai de référence même après prise en compte des incertitudes. Les présents travaux mettent en oeuvre une démarche non intrusive de quantification d'incertitude (NISP pour Non-Intrusive Spectral Projection) pour deux configurations d'intérêt pratique : un distributeur de turbine Francis avec débit et angle d'entrée incertains et un aspirateur de turbine bulbe avec conditions d'entrée (profils de vitesse,en particulier en proche paroi, et grandeurs turbulentes) incertaines. L'approche NISP est utilisée non seulement pour estimer la valeur moyenne et la variance de quantités d'intérêt mais également pour disposer d'une analyse de la variance qui permet d'identifier les incertitudes les plus influentes. Les simulations RANS, vérifiées par une démarche de convergence en maillage, ne permettent pas pour la plupart des configurations analysées d'expliquer les écarts calcul / expérience grâce à la prise en compte des incertitudes d'entrée.Nous mettons donc également en ouvre des simulations SGE en faisant appel à une stratégie originale d'évaluation de la qualité des maillages utilisés dans le cadre d'une démarche de vérification des calculs SGE. Pour une majorité des configurations analysées, la combinaison d'une stratégie SGE et d'une démarche de quantification des incertitudes permet de produire des résultats numériques fiables. La prise en compte des incertitudes d'entrée permet également de proposer une démarche d'optimisation robuste du distributeur de turbine Francis étudié
The reliable numerical simulation of hydraulic turbines performance requires : i) to includeinto the conventional RANS computations the effect of the uncertainties existing in practiceon the inflow conditions; ii) to rely on a LES (Large Eddy Simulation) strategy to improve thedescription of turbulence effects when discrepancies between RANS computations and experimentskeep arising even though uncertainties are taken into account. The present workapplies a non-intrusive Uncertainty Quantification strategy (NISP for Non-Intrusive SpectralProjection) to two configurations of practical interest : a Francis turbine distributor, with uncertaininlet flow rate and angle, and a draft-tube of a bulb-type turbine with uncertain inflowconditions (velocity distributions, in particular close to the wall boundaries, and turbulentquantities). The NISP method is not only used to compute the mean value and variance ofquantities of interest, it is also applied to perform an analysis of the variance and identify inthis way the most influential uncertainties. The RANS simulations, verified through a gridconvergence approach, are such the discrepancies between computation and experimentcannot be explained by taking into account the inflow uncertainties for most of the configurationsunder study. Therefore, LES simulations are also performed and these simulations areverified using an original methodology for assessing the quality of the computational grids(since the grid-convergence concept is not relevant for LES). For most of the flows understudy, combining a SGE strategy with a UQ approach yields reliable numerical results. Takinginto account inflow uncertainties also allows to propose a robust optimization strategy forthe Francis turbine distributor under study

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Frey, Axel [Verfasser], and Stefan [Akademischer Betreuer] Riedelbauch. "Untersuchung von periodischen und turbulenten Strömungsfluktuationen einer Francis-Turbine im Teillastbetrieb mit Laser-Doppler-Anemometrie / Axel Frey ; Betreuer: Stefan Riedelbauch." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1223928861/34.

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Žák, Radim. "Návrh oběžného kola Francisovy turbiny na zadané parametry." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228125.

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The graduation theses are focused on reconstruction of the small hydro-electric power station Harta. Design of detailed runner blading based on the parameters of the given location is part of the reconstruction. Model of the duplex Francis turbine for cast manufacturing is result of the graduation theses. Numerical description of the model was carried out using SolidWorks software.

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Bouajila, Sofien. "Analyse expérimentale et numérique des écoulements à charge partielle dans les turbines Francis - Étude des vortex inter-aubes." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI030.

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L’intégration des énergies renouvelables sur le réseau électrique entraîne de nouveaux besoins chez les exploitants de centrales hydroélectriques. Ainsi, les fabricants de turbines hydrauliques doivent garantir des plages de fonctionnement de plus en plus étendues, afin d’assurer une plus grande flexibilité d’utilisation des machines. Pour les turbines Francis, un fonctionnement en-dehors des conditions nominales implique potentiellement une augmentation des sollicitations mécaniques, notamment à faible débit (charge partielle). Cette hausse est due à l’apparition de phénomènes hydrauliques dans l’écoulement, dont notamment les vortex inter-aubes. Pour garantir des plages de fonctionnement étendues à leurs clients, les fabricants se doivent de maîtriser l’impact de telles conditions d’opération sur la durée de vie de leurs machines. Il est donc nécessaire de mieux comprendre l’écoulement complexe dans la turbine et son impact mécanique à charge partielle. Dans ce contexte, cette thèse a une double approche expérimentale et numérique. L’analyse se base sur des mesures et des observations réalisées lors d’essais sur modèles réduits. Elles ont permis de corréler les phénomènes hydrauliques observés et l’évolution des fluctuations de pression et des déformations dynamiques mesurées, pour différents points de fonctionnement. Ces résultats ont notamment été utilisés pour estimer le phénomène de fatigue lors du fonctionnement continu d’une turbine à très faible charge. La simulation numérique des fluides (CFD) a également été utilisée pour mieux comprendre les mécanismes impliqués dans la formation des vortex inter-aubes, et pour prédire le chargement dynamique qui s’exerce sur la roue à charge partielle. La validation des résultats numériques est basée sur la comparaison avec les données expérimentales issues des précédents essais sur modèles réduits
The integration of renewable energies into the electricity grid brings new needs for hydro power plant operators in terms of how they are operated. Consequently, hydraulic turbine manufacturers are required to extend their machine’s operating range in order to increase their flexibility. In the case of Francis turbines, dynamic stresses could increase in off-design conditions due to several hydraulic phenomena that appear in the flow, especially at partial load. One of them is the development of inter-blade vortices in the runner. In order to guarantee an extended operating range manufacturers have to control the impact of such operating conditions on their turbines lifetime. Therefore, a better understanding of complex partial load flows and their mechanical impact on the turbines is needed. In this context, this thesis uses both experimental and numerical approaches. Reduced scale model turbines were tested in order to correlate hydraulic phenomena observed in the flow and the evolution of pressure and strain fluctuations for different operating points. The results were then used to estimate the turbine fatigue in partial load conditions. Computational Fluid Dynamics was also used to better understand the formation of inter-blade vortices and to predict the dynamic loading on the runner at partial load. These numerical results were validated by comparison with the experimental data from the previous test rig measurements and observation campaigns

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Doussot, François. "Simulation numérique de l'écoulement de charge partielle dans les turbines Francis : analyse de la topologie et de la dynamique des vortex inter-aubes." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI069.

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Les machines hydrauliques sont conçues pour fonctionner essentiellement autour du point de fonctionnement nominal. Cependant, afin notamment d'intégrer les énergies renouvelables sur le réseau, ces machines hydrauliques doivent nécessairement faire preuve de flexibilité. Ainsi, la plage de fonctionnement des turbines Francis cherche à être étendue, notamment pour des fonctionnements à des débits plus faibles. Lorsqu'une turbine Francis fonctionne avec un débit compris entre 30 et 60% du débit nominal, l'écoulement dans la roue est caractérisé par la présence de vortex entre les aubes. Dans ces conditions, des contraintes dynamiques apparaissent dans la roue et peuvent réduire la durée de vie de la machine à cause du phénomène de fatigue mécanique. Cette étude a pour objectif d'améliorer la compréhension de la dynamique de ces phénomènes à travers une approche numérique. Des simulations ont été effectuées avec plusieurs approches de la turbulence : des simulations stationnaires (RANS), des simulations instationnaires avec une approche hybride de la turbulence (SAS) et la Simulation des Grandes Echelles (SGE).Les simulations stationnaires permettent de comprendre les phénomènes à l'origine de la formation de ces vortex. L'analyse présentée dans ce travail montre que les vortex inter-aubes sont générés à cause d'une mauvaise incidence en entrée de la roue ou à cause d'une zone de recirculation sous la roue. Différentes topologies de vortex sont mises en évidence, générées par la compétition de ces deux phénomènes. Le chargement dynamique doit être connu afin d'évaluer précisément la durée de vie d'une roue. Plusieurs points de fonctionnement ont été simulés avec des calculs instationnaires afin de comprendre comment les fluctuations de pression dépendent du point de fonctionnement de la machine. La localisation des fluctuations de pression et les fréquences associées ont été analysées et comparées à des mesures expérimentales effectuées sur un modèle réduit. Les résultats montrent que les simulations SAS permettent de mettre en évidence des mécanismes à basses fréquences de ces écoulements de charge partielle. Cependant, les fluctuations à hautes fréquences sont largement sous-estimées par cette approche. Plus particulièrement, une signature fréquentielle large bande, caractéristique de l'écoulement de charge partielle, n'est pas prédite par ces simulations. La SGE a été utilisée afin d'améliorer la prédiction de ces hautes fréquences et de comprendre l'origine de ces phénomènes instationnaires. Les résultats démontrent la pertinence de l'utilisation de ce type d'approche numérique en mettant en évidence des sources d'instabilités hautes fréquences dans la machine
Hydraulic machines are designed to operate in flow conditions close to the best efficiency point. However, to respond to the increasing demand for flexibility mainly due to the integration of renewable energy in the electric grid, the operating range of Francis turbines has to be extended towards smaller discharge levels without restriction. When Francis turbines are operated typically between 30% and 60% of the rated output power, the flow field is characterized by the appearance of inter-blade vortices in the runner. At these off-design operating conditions and due to these phenomena, dynamic stresses level can increase, and potentially lead to fatigue damage of the mechanical structure of the machine. The objective of this study is to present investigations on the dynamic behaviour of the inter-blade vortices and their impact on the runner by using numerical simulations. Computations were performed with different turbulence modelling approaches to assess their relevance and reliability: Reynolds-Averaged Navier-Stokes (RANS), Scale-Adaptive Simulations (SAS) and Large-Eddy Simulations (LES). Steady simulations aimed to better understand the emergence condition of the inter-blade vortices. The analysis showed that vortices can be generated due to poor inlet adaptation at part load, however other vortices can also be due to a local backflow in the runner. The competition between these both phenomena leads to various topologies of the inter-blade vortices. The dynamic loading on the blade has to be known in order to evaluate the lifetime of the runner by mechanical analysis. Different operating conditions have been simulated by unsteady simulations to understand how the pressure fluctuations depend on the operating conditions. The localisation of the pressure fluctuations and their frequency signature have been analysed and compared to experimental measurements performed on a scaled model. The results of SAS simulations show the driving phenomena at a low range of frequencies of the dynamic of part load conditions. However the high frequency fluctuations are underestimated by this approach. Then large eddy simulations are computed to improve the prediction of this high frequency fluctuations. The study of a wide-band frequency signature is particularly detailed in this work

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Neděla, Jiří. "CFD simulace vírové struktury v sací troubě Francisovy turbíny (Francis-99) při pod-optimálním provozu - srovnání s měřením." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-399568.

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This master's thesis deals with simulation of vortex structure which is created in the draft tube of Francis turbine, at part load flow conditions. The main objective is to get the most accurate results from the calculations, using the student license of Ansys Fluent 19.1. The results from the calculations are compared with the experiment under the Francis-99 project. Mainlly in terms of dynamic properties of vortex rope – aplitude and frequency of pressure pulsations. Additionaly the time-averaged velocity profiles are compared. I used the test-case provided by NTNU – Norwegian University of Science and Technology under the Francis-99 workshop series.

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Litera, Jiří. "Řízení vírového proudění v sací troubě vodní turbíny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318640.

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Hydraulic energy is one of the most important sources in the world for electricity production. Nowadays the trend is to limit the production of the electricity from fossil fuels and to protect the environment. The main idea is to use more renewable energy sources such as wind and solar energy. Unfortunately, these alternative sources are strongly dependent on current weather conditions, which causes the instability of the electrical grid. Luckily pumped storage and hydraulic power plants provide the solution. However, it requires an extension of the operating range of the hydraulic machines. For that reason, the water turbines now operate over and extended range of regimes, that can be quite far from the best efficiency point. Hence two types of unstable two-phase flows in the Francis turbine draft tube occur: part load overload. This diploma’s thesis is focused on the Francis turbine operating at the part load. During part load conditions the helical vortex rope is being developed in the draft tube, it causes pressure pulsation and it can lead to the hydro-acoustic resonance, which damages the elements of the power plant. The aim is to eliminate the pulsation by jet control of the swirling flow in the draft tube. In the diploma’s thesis, various approaches to jet control of the flow in conical diffuser are tested using the computational fluid dynamics.

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Kozák, Jiří. "Vírový cop při nadoptimálním průtoku Francisovou turbínou." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-231007.

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This master's thesis deals with CFD simulation of vortex rope in the elbow draft tube for overload operation of Francis turbine. The main objective of the thesis is to compare results of the CFD simulations of the original elbow draft tube with a derived straight cone draft tube considering volume and the shape of the cavitation region and dynamic flow characteristic. Results of the 3D simulations are also compared with axi-symmetric simulations, which reduce demands for computing time and power.

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Koutecký, Vojtěch. "Hydraulický systém regulace vodní turbíny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401001.

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The aim of this diploma thesis is to create a hydraulic system for water turbine control. The basic dimensioning of the hydraulic elements is included in order to build a functional hydraulic diagram.

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Hazucha, Jan. "Vliv otevření difuzoru na dynamické vlastnosti spirální vírové struktury." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401535.

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This master’s thesis deals with CFD simulation of spiral vortex structure in the diffuser of swirl generator. The objective of the thesis is to evaluate influence of change in diffuser opening angle on frequency and amplitude of pressure pulsation. All results are compared in charts which shows courses of frequencies and amplitudes along the diffuser. Two different turbulence models and several types of mesh were tested

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Ylonen, Markku. "Cavitation erosion monitoring by acoustic emission Cavitation Bubble Collapse Monitoring by Acoustic Emission in Laboratory Testing Cavitation Erosion Resistance Assessment and Comparison of Three Francis Turbine Runner Materials Estimation of Cavitation Pit Distributions by Acoustic Emission . Shedding Frequency in Erosion Evolution Tracking." Thesis, Université Grenoble Alpes, 2020. https://tel.archives-ouvertes.fr/tel-02613873.

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La cavitation est la formation de bulles de vapeur dans un liquide statique ou en écoulement. L’érosion de cavitation se produit quand ces bulles collapsent à cause de la récupération de pression. Ce phénomène peut endommager les parois à proximité desquelles les bulles collapsent. Il s’agit d’un problème majeur dans les machines hydrauliques. Par exemple, les turbines hydrauliques fonctionnent aujourd’hui souvent dans des régions défavorables du point de vue de la cavitation, pour réguler le réseau électrique. Mesurer la cavitation et le taux d’érosion est souvent très difficile voire impossible. L’émission acoustique (EA) est une méthode qui permet la mesure de cavitation sans accès direct à l’écoulement ; toutefois, les données sont difficiles à interpréter. Cette thèse présente quelques possibilités de traitement des données de l’EA pour quantifier les diamètres des indentations créées par impacts individuels de la cavitation et aussi pour évaluer l’érosion de cavitation. De plus, les taux d’érosion de trois matériaux d’aubes de turbine Francis ont été caractérisés. Les raisons pour les différences dans le taux d’érosion de deux aciers inoxydables et martensitiques sont analysées. Tous les essais de cavitation ont été réalisés dans le même tunnel de cavitation haute vitesse. Un premier résultat majeur de cette thèse est le développement d’une méthode pour compter les pics d’EA par une technique d’enveloppe du signal. Les distributions cumulées des pics d’EA sont comparées à celles des diamètres d’indentations. Une relation est proposée entre l’amplitude des pics d’EA et le diamètre des indentations. Le deuxième résultat majeur est le lien entre l’évolution de l’érosion de cavitation et la fréquence de lâcher des nuages de cavitation. Bien que les signaux d’EA soient mesurés en haute fréquence, un processus de démodulation a été mis en œuvre qui permet de mettre en évidence la basse fréquence de lâcher. Cette fréquence augmente avec la rugosité et la déformation de surface au fur et à mesure de la progression de l’endommagement. Par ailleurs, les raisons entre les différences de taux d’érosion des aciers inoxydables et martensitiques ont été identifiées : la taille des grains d’austénite initiale, les tailles des plaques et plaquettes et la quantité d’austénite résiduelle sont les principaux facteurs influants. Cette thèse propose plusieurs résultats directement utilisables, comme la classification entre les aciers inoxydables martensitiques, ainsi que des méthodes pour surveiller la cavitation mises au point en laboratoire dans un tunnel de cavitation et potentiellement applicables aux machines hydrauliques. Le résultat majeur est que l’EA a un fort potentiel pour surveiller la cavitation et l’érosion de cavitation avec l’avantage important qu’elle ne nécessite pas d’accès direct à l’écoulement
Cavitation is the formation of vapor bubbles either in a static liquid or in a liquid flow due to a drop in static pressure. When these bubbles collapse, as a result of pressure recovery, they may damage adjacent surfaces. These events are major causes of damage and nuisance in hydro machines. Modern hydro turbines are often used to regulate power grids; therefore, they may be operated out of their designed range. The flow-related optimal operation is different from the economic optimal usage. Detecting and characterizing cavitation and assessing damage during operation can be difficult or even impossible. Acoustic emission (AE) measurements provide a way to measure cavitation without access to the flow, but interpreting the data is challenging. This thesis presents insights in the ways of treating the AE data both in characterizing individual pits created by cavitation impacts and in tracking the evolution of cavitation erosion. Additionally, the erosion rates of three turbine materials were compared, and the main reasons behind the differing erosion rates of two martensitic turbine steels were discovered. The same high-speed cavitation tunnel was used in all cavitation experiments. This thesis firstly presents a method for enveloping an AE waveform signal and for counting the peak voltage values. The resulting cumulative distributions were compared to those of cavitation pit diameters, and from this comparison, a connection was proposed between AE peak voltage value and pit diameter. The second result was the connection between cavitation cloud shedding frequency and erosion evolution. The process of demodulating high frequency AE signals effectively promotes the low frequency shedding. The shedding frequency increased with accumulating material loss, and it was concluded that this increase is due to geometry effects, namely surface roughness. In addition to the two proposed methods, it was found that the decisive factors in the differing erosion rates of the martensitic stainless steels are the prior austenite grain size, packet and block sizes and the retained austenite fraction. This thesis provides guidelines directly applicable, such as the martensitic steel classifying, and methods that require further development, if one wishes to utilize them in hydro machine cavitation monitoring instead of laboratory measurements in a cavitation tunnel. The main outcome is that AE is a potential way to monitor cavitation, with the important benefit of not requiring any access to the flow

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Sitte, David. "Odezva atypického vertikálního rotoru vodní turbíny na buzení nevývažkem oběžného kola a nevývažkem rotoru generátoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443737.

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This master’s thesis deals with the dynamic behaviour of vertical Francis turbine, which is atypical its shaft length. In the first part of thesis, there is theoretic research of water turbine, which is followed by derivation of equations for the Stodola rotor. The second part deals with the creation of the turbine shaft in 1D and 3D. A modal analysis was performed in the ANSYS Workbench software, based on which the Campbell diagram is created and it was determined the critical speed. And the harmonic analysis from which was determined the forces response in radial bearings, amplitude of deviation in radial direction in the turbine impeller and the generator and the axial displacement located in turbine impeller and axial bearing. 1D and 3D solutions were compared between themselves.

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Sansevero, Glaucio. "Controle preditivo baseado em modelo para turbo-geradores hidraulicos tipo Francis." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258844.

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Orientador: Celso Pascoli Bottura
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-07T10:43:12Z (GMT). No. of bitstreams: 1 Sansevero_Glaucio_M.pdf: 643820 bytes, checksum: 45c53dc9fa719ea530adb309c5ac4ee8 (MD5) Previous issue date: 2006
Resumo: Apesar de ter surgido na indústria há mais de 20 anos, o Controle Preditivo Baseado em Modelo (MPC) não encontrou muitas aplicações no campo de controle de máquinas rotativas. A maioria das aplicações hoje são processos químicos e petroquímicos. Contudo, alguns resultados obtidos por outros autores em controle de turbinas a gás e turbinas a vapor sugerem que sua utilização pode ser interessante no controle deste tipo de máquina e, em particular, no controle de turbinas hidráulicas. Este trabalho tem por objetivo explorar a possibilidade e discutir as vantagens e desvantagens da aplicação deste método no controle de turbinas hidráulicas tipo Francis. Iniciamos o trabalho apresentando urna descrição do MPC e explicitando o algoritmo utilizado pelo controlador. Em seguida, um modelo no espaço de estado do sistema a ser controlado é desenvolvido. Finalmente, o método é aplicado no controle da máquina em questão e os resultados obtidos através de simulações são analisados
Abstract: Despite being used in the industry for more than 20 years, Model Predictive Control (MPC) has not found many applications in the field of rotating machinery controI. The majority of the applications today are chemical and petrochemical processes. However, some results obtained by other authors for the control of gas and steam turbines, suggest that its use can be interesting for the control of this type of machine, and in particular, for the control of hydraulic turbine generators. The objective of this work is to explore the possibility and to discuss the advantages and disadvantages of the application of this method on the control of a Francis hydro turbine generator. We start the discussion presenting a description of the MPC and detailing the algorithm used by the controller. After that, a state space model of the system to be controlled is developed. Finally the method is applied for the control of the hydro turbine and the results obtained trough simulation are discussed.
Mestrado
Automação
Mestre em Engenharia Elétrica

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32

Knápek, Michal. "Posouzení výhodnosti výstavby přečerpávací vodní elektrárny velkého výkonu v lokalitě Cukrová bouda, okres Šumperk." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219416.

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The subject matter of the master´s thesis is, in particular, an evaluation of the advantageousness of the construction of a pumped-storage hydroelectric power station in the vicinity of Cukrová Bouda. In the master´s thesis introduction the utilisation of pumped-storage hydroelectric power stations in providing reserve power generation to the operator of a power transmission system is discussed. The thesis then focuses on a technical design solution where two alternatives are drawn up for which the nominal parameters of individual designs for a pumped-storage hydroelectric power station are specified. The following part deals with the impact of the structure and the plant’s subsequent operation on the environment. A further key part is the determination of investment and subsequent operating costs and an evaluation of the plant according to economic pointers. The final part of the master´s thesis contains a SWOT analysis and an assumed programme of works for the plant’s preparation and actual construction. The conclusion contains an overall evaluation.

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Ng, TB. "Unsteady operation of the Francis turbine." Thesis, 2007. https://eprints.utas.edu.au/21027/1/whole_NgTzuuBin2007_thesis.pdf.

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Increasing interconnection of individual power systems into major grids has imposed more stringent quality assurance requirements on the modelling of hydroelectric generating plant. This has provided the impetus for the present study in which existing industry models used to predict the transient behaviour of the Francis-turbine plants are reviewed. Quasi-steady flow models for single- and multiple-turbine plants developed in MATLAB Simulink are validated against field test results collected at Hydro Tasmania's Mackintosh and Trevallyn power stations. Nonlinear representation of the Francis-turbine characteristics, detailed calculation of the hydraulic model parameters, and inclusion of the hydraulic coupling effects for multiple-machine station are found to significantly improve the accuracy of predictions for transient operation. However, there remains a noticeable phase lag between measured and simulated power outputs that increases in magnitude with guide vane oscillation frequency. The convective lag effect in flow establishment through the Francis-turbine draft tube is suspected as a major contributor to this discrepancy, which is likely to be more important for hydro power stations with low operating head and short waterway conduits. To further investigate these effects, the steady flow in a typical Francis-turbine draft tube without swirl is analysed computationally using the commercial finite volume code ANSYS CFX. Experimental studies of a scale model draft tube using air as the working medium are conducted to validate and optimise the numerical simulation. Surprisingly, numerical simulations with a standard k-ε turbulence model are found to better match experimental results than the steady-flow predictions of more advanced turbulence models. The streamwise pressure force on the draft tube is identified as a quantity not properly accounted for in current industry models of hydro power plant operation. Transient flow effects in the model draft tube following a sudden change in discharge are studied computationally using the grid resolution and turbulence model chosen for the steady-flow analysis. Results are compared with unsteady pressure and thermal anemometry measurements. The three-dimensional numerical analysis is shown to predict a longer response time than the one-dimensional hydraulic model currently used as the power industry standard. Convective lag effects and fluctuations in the draft tube pressure loss coefficient are shown to largely explain the remaining discrepancies in current quasi-steady predictions of transient hydro power plant operation.

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Yih, Per-Wha, and 余培華. "Study on Cavitation Characteristics in Francis Turbine Draft-Tube." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/71685373993560697832.

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碩士
國立中興大學
機械工程學系所
98
Abstract This study focuses on the cavitation detection in the draft tube of hydraulic turbines. One seismic transducers is installed on the 67MW and the other on the draft tube of a 105MW prototype Francis turbine to measure the structural vibration for ten varying loads. The signal is proceses via FFT and wavelet to analyze the spectra and the time-frequency characteristics. In additions, sorting the data from new Tienlun、Maan and Shihlin hydropower test records of Taiwan power company can help to illustrate the experimental results. The experimental results show that：（1）The cavitation detected in the draft tube is caused by three different flow conditions from the runner impeller outlet. While the machine operates at low load , massive bubbles are produced. The Karman vortex cavitation is formed when operated at the middle load the middle load.And at high load, no obvious cavitation is observed. Their characteristic frequencies are concentrated around 3KHz with a frequency band ranging within 1 KHz ~5 KHz.（2）The signal frequency ranged within 300Hz~500 Hz is probably caused by the period pressure pulse induced at the runner outlets.（3）when operating around 40％~80％ full load ,the period pressure pulse is significantly induced by the swirl at draft tube.（4）Not only the amount of purged air and the length of air-supply pipe can leviate the strength of swirl at the draft tube.Meanwhile but they will also lead to series cavitation at low loads, .On the other hand, if the air-supply pipe is stalled below the runner cone, the cavitation at the low load will be largely improved.However this will also induce the more turbulent flow in draft tube,which may cause serious vortex and cavitation in the wake of the air- supply pipe. Keywords：hydraulic turbine , cavitation , spectra

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Chan, Sze Bun. "Finite element analysis on vibration behavior and fatigue cracking prediction of a Francis type hydraulic turbine." Thesis, 1999. http://hdl.handle.net/2429/9445.

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GMS turbine cracking problem was investigated using finite element analysis. Analysis results confirmed that fatigue cracking could occur due to resonance induced by pressure variation as turbine blades pass wicket gates. Analyses also showed that fatigue life could be extremely low due to extremely high cycles experienced by the turbine. Installation of blade stiffeners and thickness modifications could change the natural frequency of the turbine. However, the modifications could cause efficiency reduction, cavitation behavior change or structural weakness. Therefore no feasible modifications were suggested.

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Bodson-Clermont, Paule-Marjolaine. "Modélisation statistique de l’érosion de cavitation d’une turbine hydraulique selon les paramètres d’opération." Thèse, 2015. http://hdl.handle.net/1866/13433.

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Dans une turbine hydraulique, la rotation des aubes dans l’eau crée une zone de basse pression, amenant l’eau à passer de l’état liquide à l’état gazeux. Ce phénomène de changement de phase est appelé cavitation et est similaire à l’ébullition. Lorsque les cavités de vapeur formées implosent près des parois, il en résulte une érosion sévère des matériaux, accélérant de façon importante la dégradation de la turbine. Un système de détection de l’érosion de cavitation à l’aide de mesures vibratoires, employable sur les turbines en opération, a donc été installé sur quatre groupes turbine-alternateur d’une centrale et permet d’estimer précisément le taux d’érosion en kg/ 10 000 h. Le présent projet vise à répondre à deux objectifs principaux. Premièrement, étudier le comportement de la cavitation sur un groupe turbine-alternateur cible et construire un modèle statistique, dans le but de prédire la variable cavitation en fonction des variables opératoires (tels l’ouverture de vannage, le débit, les niveaux amont et aval, etc.). Deuxièmement, élaborer une méthodologie permettant la reproductibilité de l’étude à d’autres sites. Une étude rétrospective sera effectuée et on se concentrera sur les données disponibles depuis la mise à jour du système en 2010. Des résultats préliminaires ont mis en évidence l’hétérogénéité du comportement de cavitation ainsi que des changements entre la relation entre la cavitation et diverses variables opératoires. Nous nous proposons de développer un modèle probabiliste adapté, en utilisant notamment le regroupement hiérarchique et des modèles de régression linéaire multiple.
Cavitation erosion which results from repeated collapse of transient vapor cavities on solid surfaces is a constant problematic in hydraulic turbine runners and continues to enforce costly repair and loss of revenues. A vibratory detection system of cavitation erosion was installed 10 years ago for continuous monitoring of 4 hydropower units. A new hardware version of the system was developed and installed in 2010. This new system configuration is more reliable and allows more accurate evaluation of the cavitation erosion of the runners in kg/10 000 h. The first objective of this study is to investigate cavitation behavior upon one generating unit and to build a statistical model which will allow prediction of instant cavitation related to operating variables, such as gate opening, water flow, headwater level, tailwater levels, etc. The second objective is to develop a methodology for the reproducibility of the studies to other sites. A retrospective study will be conducted and we will mainly focus on data available since the system update in 2010. The preliminary analysis enhanced the complexity of the phenomenon. Indeed, changes in the relationship between cavitation and various operating variables were observed and could be due to a seasonal behavior or different operating conditions. Using hierarchical clustering and regression models, we formalize this heterogeneity by developing a model which includes operating variables such as active power, tailwater level and gate opening.

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Giosio, DR. "Unsteady operation and rapid start up of Francis turbines." Thesis, 2015. https://eprints.utas.edu.au/23222/1/Giosio_whole_thesis.pdf.

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Hydropower is a key component in a decentralised market with increasing penetration of often intermittent renewable energy resources. There is growing need for large-scaleoperators to develop a more comprehensive understanding of the full dynamic capabilities of a given hydropower plant, while developments in small-scale hydro will aid in waste energy recovery and rural electrification. In particular, greater confidence in the transient response characteristics of hydro generators will in turn enable and encourage increased contributions from other much needed large scale renewable energy sources, such as wind and solar power, without compromising grid stability. The major drawback of current pump-as-turbine (PAT) micro-hydro solutions is the very narrow effective operating band and lack of universal performance prediction models. To address this, the design process and installed performance of a new 6.2 kW PAT microhydro turbine unit and test facility is presented. Steady state testing over the full operating range indicates a best efficiency of 79% and demonstrates near peak efficiency operation over an extended range of head and flow conditions. The developed turbine is a promising prototype of a lower cost alternative for installations where the capital costs associated with conventional Francis turbine units are often prohibitive. The potential for hydraulic turbines to provide rapid reserve power generation is investigated experimentally by transitioning the micro-hydro unit from a modified synchronous condenser mode under varying levels of tail water depression and inlet guide vane (IGV) opening rates. Similar full-scale testing on a 116 MW Francis turbine generating set revealed an undesirable power draw and subsequent output power oscillations during the early stages of transition limiting the potential contribution of the tested unit. Direct shaft power measurements of the micro-hydro unit during transition demonstrate the presence of an inhibiting mechanical torque applied to the runner during low guide vane opening angles, of the order of 2% of rated, which is believed to initiate the electromechanical response seen at full-scale. The temporal location and duration of the applied negative torque was found to be highly dependent on IGV opening rate while the effect of tail water depression level was insignificant under constant head conditions. The magnitude of the power draw was independent of initial tail water depression level, while an increased opening rate marginally reduced the observed power draw at the laboratory scale. An improved one-dimensional numerical model of a Francis turbine hydropower plant for dynamic response studies is presented. The model is based on the equations of motion and continuity, while the conventional representation of the hydraulic turbine as an orifice is improved upon to account for machine behaviour away from design using known inlet flow velocity vectors. The new model remains valid at low IGV angles, where the traditional one-dimensional model breaks down, and is validated against full-scale transient test data. Furthermore, simulation results support the findings of experimental work indicating a high dependence on IGV opening rate in relation to output response during transition from tail water depression mode. Ultimately, the research presented assesses the feasibility of transitioning a Francis turbine unit from tail water depression mode to generation for the purpose of providing rapid load support to the local grid. A three-stage transition mechanism responsible for the observed output response is proposed based on the findings from both experimental and numerical investigations, while key parameters and potential risks are identified. Finally an improved set of operational guidelines are presented for increasing the provision of rapid reserve power generation for maintaining system stability and ensuring a secure electricity supply.

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