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  • Experimental study on the added mass and damping of a disk submerged in a partially fluid-filled tank with small radial confinement

     Valentín Ruiz, David; Presas Batllo, Alexandre; Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen
    Journal of fluids and structures
    Vol. 50, p. 1-17
    DOI: 10.1016/j.jfluidstructs.2014.06.006
    Date of publication: 2014-07-16
    Journal article

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    The dynamic response of submerged and confined disk-like structures is of interest in engineering applications, such as in hydraulic turbine runners. This response is difficult to be estimated with accuracy due to the strong influence of the boundary conditions. Small radial gaps as well as short axial distances to rigid surfaces greatly modify the dynamic response because of the added mass and damping effects. In this paper, the influence of the axial nearby rigid distance on the dynamic response of a submerged disk is evaluated when the radial gap is very small. Moreover, the effects of the fluid depth and fluid viscosity on the natural frequencies and damping ratio of the submerged disk are studied. The study has been performed experimentally and numerically using structural¿acoustic simulations. For the experimental investigation a test rig has been developed. It consists of a disk attached to a shaft and confined with a small radial gap inside a cylindrical container full of water. The disk can be moved up and down along the shaft to vary the axial distance to the nearby rigid surface. Piezoelectric patches are used to excite the disk and the response is measured with submersible accelerometers. Several excitation patterns can be used due to the disposition of these piezoelectric patches. For each configuration tested, the dynamic response of the structure is studied analyzing the natural frequencies and damping ratio of the disk attached to the shaft. The numerical results have been compared with the experimental results.

    The dynamic response of submerged and confined disk-like structures is of interest in engineering applications, such as in hydraulic turbine runners. This response is difficult to be estimated with accuracy due to the strong influence of the boundary conditions. Small radial gaps as well as short axial distances to rigid surfaces greatly modify the dynamic response because of the added mass and damping effects. In this paper, the influence of the axial nearby rigid distance on the dynamic response of a submerged disk is evaluated when the radial gap is very small. Moreover, the effects of the fluid depth and fluid viscosity on the natural frequencies and damping ratio of the submerged disk are studied. The study has been performed experimentally and numerically using structural–acoustic simulations. For the experimental investigation a test rig has been developed. It consists of a disk attached to a shaft and confined with a small radial gap inside a cylindrical container full of water. The disk can be moved up and down along the shaft to vary the axial distance to the nearby rigid surface. Piezoelectric patches are used to excite the disk and the response is measured with submersible accelerometers. Several excitation patterns can be used due to the disposition of these piezoelectric patches. For each configuration tested, the dynamic response of the structure is studied analyzing the natural frequencies and damping ratio of the disk attached to the shaft. The numerical results have been compared with the experimental results.

  • Numerical and experimental study of a nearby solid boundary and partial submergence effects on hydrofoil added mass

     de la Torre Rodriguez, Oscar; Escaler Puigoriol, Francesc Xavier; Egusquiza Estevez, Eduardo; Farhat, Mohamed
    Computers and fluids
    Vol. 91, p. 1-9
    DOI: 10.1016/j.compfluid.2013.12.003
    Date of publication: 2014-03-05
    Journal article

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    The influence of the boundary conditions on the added mass of a NACA0009 cantilever hydrofoil has been numerically and experimentally investigated. The study has been focused on the effects of a lateral solid wall close to the hydrofoil tip side and of a partially wetted vertical hydrofoil at different levels with the free surface parallel to the span. A detailed fluid-structure model has been built for both cases and a modal analysis has been carried out. The numerical three first natural frequencies have been used to calculate the added mass coefficients. These coefficients have been compared with the results of the analogous experiments carried out by means of an onboard excitation and response system based on piezoelectric patches. The obtained results are in reasonable good agreement with experimental data. The proximity of a lateral solid wall provokes an increase of the added mass experienced by the hydrofoil which can be approximated by a 2nd order polynomial function for both bending and torsion modes. On the other hand, the increase of the added mass with the level of partial submergence is found to be dependent on the relative displacements of the hydrofoil submerged part and hence on the mode shape. © 2013 Elsevier Ltd.

  • Numerical and experimental analysis of the dynamic response of large submerged trash-racks

     Huang, Xingxing; Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo; Presas Batllo, Alexandre; Guardo Zabaleta, Alfredo de Jesús
    Computers and fluids
    Vol. 71, num. January, p. 54-64
    DOI: 10.1016/j.compfluid.2012.09.016
    Date of publication: 2013-01-30
    Journal article

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    This paper investigates the effect of water in the dynamic response of large trash-racks used in hydropower plants. These are large structures that are fully submerged in water and located in the hydraulic circuits to prevent debris and large bodies from entering the turbine. These structures are prone to suffering fatigue damage. Broken bars are rather common, which can produce damage in the turbine and other hydraulic components. To avoid fatigue problems, the trash-racks must be designed to avoid coincidence between the excitation frequencies of vortex shedding and the natural frequencies of the trash rack. Therefore, it is of paramount importance to know which are the natural frequencies and the associated mode-shapes, so as to avoid fluid–structure coupling (lock-in), which can lead to high vibration levels. Finite element models, including the surrounding mass of water, are used for this study. The methodology is applied to two existing trash-racks by calculating the modal parameters and using the numerical finite element model. An experimental investigation is also carried out in one of the trash-racks by impacting the underwater grille and measuring the response using submergible accelerometers. Experimental modal analysis is utilized to extract the modal characteristics of the actual trash rack. There is a good agreement between the numerical and the experimental results. With the validated model, the effects of fluid added mass and damping on the dynamic response of both trash-racks are evaluated and discussed in order to extract some common conclusions.

  • Assessment of the economic and environmental impact of double glazed façade ventilation systems in Mediterranean climates

     Valentín Ruiz, David; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Alavedra, Pere
    Energies
    Vol. 6, p. 5069-5087
    DOI: 10.3390/en6105069
    Date of publication: 2013-09-30
    Journal article

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    Free convection is the most often used method in order to reduce solar load gains on a building with double glazed façades (DGFs). However, depending on the climate factors, the thermal performance of a DGF may not be satisfactory and extra energy costs are required to obtain suitable comfort conditions inside the building. Forced ventilation systems are a feasible alternative to improve the thermal performance of a DGF in Mediterranean climates where large solar gains are a permanent condition throughout the year. In this paper the feasibility of using diverse forced ventilation methods in DGF is evaluated. In addition, an economical comparison between different mechanical ventilation systems was performed in order to demonstrate the viability of DGF forced ventilation. Moreover, an environmental study was carried out to prove the positive energetic balance on cooling loads between free and forced convection in DGF for Mediterranean climates. For this investigation, a CFD model was used to simulate the thermal conditions in a DGF for the different ventilation systems. Results obtained for heat flux, temperature and reductions in solar load gains were analyzed and applied for the economic and environmental research.

  • Experimental investigation of added mass effects on a hydrofoil under cavitation conditions

     Torre Rodriguez, Oscar de La; Escaler Puigoriol, Francesc Xavier; Egusquiza Estevez, Eduardo; Farhat, Mohamed
    Journal of fluids and structures
    Vol. 39, p. 173-187
    DOI: 10.1016/j.jfluidstructs.2013.01.008
    Date of publication: 2013-03-13
    Journal article

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    The influence of leading edge sheet cavitation and supercavitation on the added mass effects experienced by a 2-D NACA0009 truncated hydrofoil has been experimentally investigated in a hydrodynamic tunnel. A non-intrusive excitation and measuring system based on piezoelectric patches mounted on the hydrofoil surface was used to determine the natural frequencies of the fluid¿structure system. The appropriate hydrodynamic conditions were selected to generate a range of stable partial cavities of various sizes and also to minimize the effects of other sources of flow noise and vibrations. The main tests were performed for different sigma values under a constant flow velocity of 14 m/s and for incident angles of both 1° and 2°. Additionally, a series of experiments in which the hydrofoil was submerged in air, partially and completely submerged in still water and without cavitation at 7 and 14 m/s were also performed. The maximum added mass effect occurs with still water. When cavitation appears, the added mass decreases because the cavity length is increased, and the added mass is minimum for supercavitation. A linear correlation is found between the added mass coefficients and the entrained mass that accounts for the mean density of the cavity, its dimensions and its location relative to the specific mode shape deformation.

    The influence of leading edge sheet cavitation and supercavitation on the added mass effects experienced by a 2-D NACA0009 truncated hydrofoil has been experimentally investigated in a hydrodynamic tunnel. A non-intrusive excitation and measuring system based on piezoelectric patches mounted on the hydrofoil surface was used to determine the natural frequencies of the fluid–structure system. The appropriate hydrodynamic conditions were selected to generate a range of stable partial cavities of various sizes and also to minimize the effects of other sources of flow noise and vibrations. The main tests were performed for different sigma values under a constant flow velocity of 14 m/s and for incident angles of both 1° and 2°. Additionally, a series of experiments in which the hydrofoil was submerged in air, partially and completely submerged in still water and without cavitation at 7 and 14 m/s were also performed. The maximum added mass effect occurs with still water. When cavitation appears, the added mass decreases because the cavity length is increased, and the added mass is minimum for supercavitation. A linear correlation is found between the added mass coefficients and the entrained mass that accounts for the mean density of the cavity, its dimensions and its location relative to the specific mode shape deformation.

  • Use of Coanda nozzles for double glazed façades forced ventilation

     Valentín Ruiz, David; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Alavedra, Pere
    Energy and buildings
    Vol. 62, p. 605-614
    DOI: 10.1016/j.enbuild.2013.03.046
    Date of publication: 2013-04-29
    Journal article

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    In this paper the feasibility of using nozzles for DGF ventilation is evaluated. The nozzles selected for this study are based on the Coanda effect. For this investigation, a CFD model was used to simulate a Coanda nozzle. The modeled nozzle was simulated for different flow rate conditions and velocity and pressure fields obtained in the nozzle outlet were imposed as an inlet boundary condition in an upper crossed lateral ventilation model for a DGF. Results obtained for heat flux, and reductions in solar gain loads for different operating conditions were obtained and compared against previous results for vertical and horizontal DGF ventilation in a similar geometry.

  • Análisis y diseño de la geometría de las obras de toma y rejas de entrada en los A.H. de alto Tâmega y Daivões - Informe preliminar # 4

     Hernando Matellano, Félix; Chacón Llorente, Rafael; de la Torre Abietar, Luis; López Nieto, Javier; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo
    Date: 2013-04-28
    Report

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    Resultados preliminares obtenidos para las simulaciones de flujo a través de la boca de toma OPTIMIZADA del Grupo 1 (cota 201.5 m) en el A.H. Daivões para el 100 % (110 m3/s) del caudal máximo de turbinación y cotas de almacenamiento en embalse 219 y 223 m.

  • Memoria Predictivo 2013-UPH Ebro-Pirineos

     Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo; Castañer Rioboo, David; Presas Batllo, Alexandre; Valentín Ruiz, David
    Date: 2013-12-12
    Report

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    Activitats relacionadas amb la monitoritzacio on-line de les centrals de Sallente, Montamara y Moralets. Activitats off-line de totes les centrals de les unitats tècniques de Lleida i Pont de Suert. Es descriuen també les actuacions especials de mesures realitzades a centrals

  • Memoria Predictivo 2013-UPH Sur

     Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo; Castañer Rioboo, David; Presas Batllo, Alexandre; Valentín Ruiz, David
    Date: 2013-12-10
    Report

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    Activitats relacionadas amb la monitoritzacio on-line de lA centrals de Guillena. Activitats off-line de totes les centrals de les agrupacions d¿aquesta UPH. Es descriuen també les actuacions més rellevants derivades de les mesures on i off line.

  • Análisis y diseño de la geometría de las obras de toma y rejas de entrada en los A.H. de alto Tâmega y Daivões - Informe preliminar # 3

     Hernando Matellano, Félix; Chacón Llorente, Rafael; de la Torre Abietar, Luis; López Nieto, Javier; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo
    Date: 2013-04-20
    Report

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    Resultados preliminares obtenidos para las simulaciones de flujo a través de la boca de toma del Grupo 1 (cota 201.5 m) en el A.H. Daivões para el 100 % (110 m3/s) y 40 % (44 m3/s) del caudal máximo de turbinación

  • Análisis y diseño de la geometría de las obras de toma y rejas de entrada en los A.H. de alto Tâmega y Daivoes - Informe preliminar # 5

     Hernando Matellano, Félix; Chacón Llorente, Rafael; de la Torre Abietar, Luis; López Nieto, Javier; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo
    Date: 2013-05-01
    Report

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    Resultados preliminares obtenidos para las simulaciones de flujo a través de una boca de toma en el A.H. Tâmega para el 100 % (100 m3/s) y 40 % (40 m3/s) del caudal máximo de turbinación y nivel de superficie libre en cota 312 m.

  • Informe CH Cornatel - on-line- enero a junio 2013

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen
    Date: 2013-07-01
    Report

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    Es fa un resum de les mesureson line rebudes en els mesos de gener a juny de 2013 per als dos grups funcionant individualment o de forma simultània. Es presta atenció especial al nivell de vibració de la canonada d'aspiració en funció de la càrrega.

  • Informe Cavitació CH Lleida

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen
    Date: 2013-04-15
    Report

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    En el grup 1 de la CH de Lleida té el marge de 3-1,5 MW com a zona de cavitació de la màquina, de manera que la màquina no treballa en aquest rang de potències. Per confirmar la zona de cavitació s'han realitzat una campanya d'assajos

  • Mediciones preliminares campanas extractoras

     Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo; Castañer Rioboo, David
    Date: 2013-11-15
    Report

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    Els objectius de les mesures són: -Conèixer la pressió en funció del cabal segons el nombre de revolucions per minut del motor. -Conèixer el soroll emès per la màquina D'altra banda, s'han pres les dimensions de les campanes proporcionades a fi de conèixer les diferències constructives entre elles

  • Análisis y diseño de la geometría de las obras de toma y rejas de entrada en los A.H. de alto Tâmega y Daivões - Informe preliminar # 1

     Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo; Hernando Matellano, Félix; Chacón Llorente, Rafael; de la Torre Abietar, Luis; López Nieto, Javier
    Date: 2013-03-05
    Report

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    Resultados preliminares obtenidos para las simulaciones de flujo a través de la boca de toma del Grupo 1 (cota 201.5 m) en el A.H. Daivões para el 100 % (110 m3/s) y 40 % (44 m3/s) del caudal máximo de turbinación.

  • Análisis y diseño de la geometría de las obras de toma y rejas de entrada en los A.H. de alto Tâmega y Daivoes - Informe preliminar # 6

     Hernando Matellano, Félix; Chacón Llorente, Rafael; de la Torre Abietar, Luis; López Nieto, Javier; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo
    Date: 2013-05-10
    Report

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    Resultados preliminares obtenidos para las simulaciones de flujo a través de las bocas de toma de los Grupos 1 (cota 201.5 m) y 2 (cota 197.5 m) en el A.H. Daivões para diversos caudales de turbinación

  • Análisis y diseño de la geometría de las obras de toma y rejas de entrada en los A.H. de alto Tâmega y Daivoes - Informe preliminar # 7

     Hernando Matellano, Félix; Chacón Llorente, Rafael; de la Torre Abietar, Luis; López Nieto, Javier; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo
    Date: 2013-05-30
    Report

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    Resultados preliminares obtenidos para las simulaciones de flujo a través de las bocas de toma en el A.H. Tâmega para el 100 % (100 m3/s) y 40 % (40 m3/s) del caudal máximo de turbinación y nivel de superficie libre en cota 312 m

  • Memoria Predictivo 2013-UPH Noroeste

     Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo; Castañer Rioboo, David; Presas Batllo, Alexandre; Valentín Ruiz, David
    Date: 2013-12-09
    Report

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    Activitats relacionadas amb la monitoritzacio on-line de la central de Cornatel. Activitats off-line de totes les centrals de les agrupacions d¿aquesta UPH. Es descriuen també les actuacions més rellevants derivades de les mesures on i off line.

  • Comportamiento vibratorio del alternador de la CH Lleida

     Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo
    Date: 2013-03-15
    Report

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    En el grup 1 de la CH de Lleida s'han mesurat vibracions importants d'origen electromagnètic. Per conèixer el motiu d'aquestes vibracions, s'ha realitzat una campanya de mesuraments que té els següents objectius: -Determinació de les freqüències i els modes propis de l'estator de l'alternador. -Càlcul de la manera de vibració de l'estator

  • Informe CH Cornatel - on-line- julio-noviembre 2013

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Castañer Rioboo, David
    Date: 2013-11-30
    Report

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    Es fa un resum de les mesures on line rebudes en els mesos de juliol a novembre de 2013 per als dos grups funcionant individualment o de forma simultània. Es presta atenció especial al nivell de vibració del tub d'aspiració en funció de la càrrega.

  • Banco de ensayos para campanas de cocina

     Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo; Castañer Rioboo, David
    Date: 2013-10-10
    Report

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    Amb l'objectiu de mesurar les prestacions de diferents campanes de cuina, s'ha proposat el disseny d'un banc d'assaig únic que pugui adaptar-se als diferents dissenys.

  • Diseño innovador campana Pando

     Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo; Castañer Rioboo, David
    Date: 2013-12-20
    Report

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    Proposta disseny innovador d¿una campana extractora que tingui més capacitat d¿aspiració, faci menys soroll i tingui més facilitat de neteja

  • Análisis y diseño de la geometría de las obras de toma y rejas de entrada en los A.H. de alto Tâmega y Daivões - Informe preliminar # 2

     Hernando Matellano, Félix; Chacón Llorente, Rafael; de la Torre Abietar, Luis; López Nieto, Javier; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo
    Date: 2013-04-01
    Report

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    Resultados preliminares obtenidos para las simulaciones de flujo a través de la boca de toma del Grupo 1 (cota 201.5 m) en el A.H. Daivões para el 100 % (110 m3/s) y 40 % (44 m3/s) del caudal máximo de turbinación.

  • FP7-608532-HYPERBOLE - HYDROPOWER PLANTS PERFORMANCE AND FLEXIBLE OPERATION TOWARDS LEAN INTEGRATION OF NEW RENEWABLE ENERGIES

     Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Fontanals Garcia, Alfred; Presas Batllo, Alexandre; Valentín Ruiz, David
    Competitive project

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  • DPI2012-36264 - Análisis de la interacción fluido-estructura en perfiles hidrúlicos de baja vorticidad y su efecto en la respuesta dinámica

     Egusquiza Estevez, Eduardo; Guardo Zabaleta, Alfredo de Jesús; Valero Ferrando, Mª Del Carmen; Escaler Puigoriol, Francesc Xavier; Jou Santacreu, Esteban; Fontanals Garcia, Alfred; Presas Batllo, Alexandre; Valentín Ruiz, David
    Competitive project

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  • Fluid Dynamic Characterization of Vortex Generators and Two-dimensional Turbulent Wakes  Open access

     Fernandez Gamiz, Unai
    Universitat Politècnica de Catalunya
    Theses

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    Resumen de la tesis de 4000 caracteres máximo (si se superan los 4000 se cortará automáticamente)Lugar Fecha Ingeniería Mecánica, Fluidos y Aeronáutica220504220403220404UNAI FERNANDEZ GAMIZEl principal objetivo de esta tesis es la caracterizacion fluidodinamica del flujo en la estela de un generador de vortices asi como la investigacion de su influencia en la separacion de la capa limite. Para ello se han llavado a cabo diversas simulaciones numericas y se ha analizado el caso particular de un unico generador de vortices en una placa plana. Para evaluar el efecto del flujo inducido por el generador de vortices se ha diseñado un generador de vortices rectangular y se ha analizado numericamente. Se han realizado simulaciones en estado estacionario en tres dimensiones a bajos numeros de Reynolds y se han comparado con datos experimentales para estudiar la autosemejanza y la simetria helicoidal en el flujo en la estela de un generador de vortices. Los resultados computacionales han sido capaces de reproducir con considerable fiabilidad de los vortices generados en la estela del generador de vortices. Ademas, se ha realizado un estudio detallado bidimensional de los parametros que definen el equilibrio de la estela en dos diferentes casos: una doble placa plana y un perfil aerodinamico simetrico (NACA0012). Ambos casos han sido analizados numericamente y los resultados han sido comparados con datos experimentales. Se ha estudiado la autosimilitud en la estela de ambas geometrias y los resultados numericos muestran una alta coincidencia con los datos experimentales. Esta tesis ha sido dividida en 5 partes fundamentales:PARTE I. En esta parte se ha presentado tanto la importancia que este trabajo de investigacion tiene en el mundo cientifico e industrial asi como la principal motivacion para llevar a cabo estas investigaciones. Se ha descrito detalladamente los diferentes modelos existentes sobre generadores de vortices haciendo especial hincapie en aquellos cuya aplicacion primordial sea las turbinas eolicas. Ademas se ha hecho una extensa explicacion sobre el estado del arte de la autosemejanza y los parametros de equilibrio de estelas turbulentas bidimensionales.PARTE II. Los tres capitulos que componen esta parte son la base fundamental de esta tesis. En esta parte de la tesis, se ha realizado una descripcion detallada de los modelos de generadores de vortices usados en esta investigacion asi como una comparacion de los resultados computacionales con datos experimentales en tunel de viento llevados a cabo por C.M. Velte, como herramienta de validacion de los resultados computacionales. En el capitulo 5 se describe exhaustivamente como se ha implantado el BAY model dentro del codigo CFD EllipSys3D. Esta implementacion se ha hecho en estrecha colaboracion con P.E. Rethore y N.N. S?rensen. Por ultimo, el capitulo 7 describe el estudio parametrico sobre la dependencia del angulo de ataque del generador de vortices. Para este estudio parametrico se han selecionado cuatro angulos de ataque deferentes: 20º, 25º, 30º y 35º.PARTE III. Esta parte de la tesis describe el comportamiento de autosimilaridad de la estela aguas abajo de un generador de vortices rectangular sobre una placa plana. Las simulaciones han demostrado alta fiabilidad a la hora de capturar el comportamiento helicoidal de la estela cuando se comparan con datos experimentales.PARTE IV. Esta parte contiene una descripcion de la autosimilaridad y de los parametros que definen el estado de equilibrio de la estela bidimensional aguas abajo de dos diferentes casos: una doble placa plana y un perfil aerodinamico simetrico (NACA0012). Ambos casos se han estudiado numericamente y se han comparado con datos experimentales llevados a cabo por Hebbar 1986.

    The main objective of this PhD thesis is the fluid dynamic characterization of the flow behind vortex generators (VG) as well as to investigate their influence in the separation of the boundary layer. CFD simulations have been carried out for the analysis of the flow downstream a single vortex generator on a flat plate. In order to evaluate the induced flow effect of the VG, a test case of a single rectangular VG has been designed and the flow have been numerically simulated and analyzed. Three-Dimensional steady state simulations at low Reynolds number have been performed using EllipSys3D CFD code and the computational results have been compared with experimental data. The self-similar behavior and the helical symmetry on the VG induced flow have been studied. The computations have demonstrated considerable reliability when reproducing the physics of the VG by a rectangular vortex generator. Furthermore, a detailed analysis of the equilibrium parameters has been made on a two-dimensional turbulent wake in two different test cases: a twin-plate and a symmetric airfoil (NACA0012). Both cases have been numerically analyzed and the computational results have been compared with experimental observations. The self-similar behaviour on the wake generated by a twin-plate and a symmetric airfoil has been tested and the CFD results match the experimental observations reasonably well.This thesis has been divided into five main parts:PART I. In this part is presented the importance of this research as well as the main motivation to carry out such work. An extensive description of the state of the art on vortex generators models is presented with high emphasis on wind turbine applications. Further, a very detailed explanation of the state of the art on self-similarity and on two-dimensional turbulent wake equilibrium is given.PART II. The three chapters of this part comprise the foundation of this thesis. In this part there is a detailed description of the vortex generator models used in this research, as well as a comparison of the computational results with the wind tunnel experiments carried out by Clara M. Velte, as a validation tool of the computations. The implementation of the BAY model into the EllipSys CFD code is described in Chapter 5 and it was performed in conjunction with N.N. S?rensen and P.E. Rethore. Finally a parametric study of the device angle dependency of a single VG on a flat plate is described in Chapter 7. Four different angles of attack have been selected for this parametric study: 20º, 25º, 30º and 35º.PART III. In this part, a self-similarity analysis has been made on a single rectangular VG on a flat plate. The simulations were able to capture the helical behaviour of the vortex generator wake with good accuracy when comparing with the experimental data. A very detailed description of the downstream evolution of the helical parameters in the computations is presented in this chapter 8 and compared with experimental results.

  • Influence of nearby rigid surfaces on natural frequencies in a submerged disk

     Valentín Ruiz, David; Presas Batllo, Alexandre; Valero Ferrando, Mª Del Carmen; Egusquiza Estevez, Eduardo
    IAHR International Workshop on Cavitation and Dynamic Problems in Hydraulic Machinery
    Presentation's date: 2013-09-10
    Presentation of work at congresses

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  • Numerical study of the vortex shedding in a Donaldson-type hydrofoil

     Fontanals Garcia, Alfred; Guardo Zabaleta, Alfredo de Jesús; Zobeiri, Amirreza; Egusquiza Estevez, Eduardo; Farhat, Mohamed; Avellan, François
    IAHR International Workshop on Cavitation and Dynamic Problems in Hydraulic Machinery
    p. 21
    Presentation's date: 2013-09-09
    Presentation of work at congresses

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  • Dynamic behaviour of pump-turbine runner: From disk to prototype runner

     Huang, Xingxing; Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Presas Batllo, Alexandre
    International Conference on Pumps and Fans with Compressors and Wind Turbines
    DOI: 10.1088/1757-899X/52/2/022036
    Presentation's date: 2013-09-19
    Presentation of work at congresses

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    In recent decades, in order to increase output power of hydroelectric turbomachinery, the design head and the flow rate of the hydraulic turbines have been increased greatly. This has led to serious vibratory problems. The pump-turbines have to work at various operation conditions to satisfy the requirements of the power grid. However, larger hydraulic forces will result in high vibration levels on the turbines, especially, when the machines operate at off-design conditions. Due to the economic considerations, the pump-turbines are built as light as possible, which will change the dynamic response of the structures. According to industrial cases, the fatigue damage of the pump-turbine runner induced by hydraulic dynamic forces usually happens on the outer edge of the crown, which is near the leading edges of blades. To better understand the reasons for this kind of fatigue, it is extremely important to investigate the dynamic response behaviour of the hydraulic turbine, especially the runner, by experimental measurement and numerical simulation. The pump-turbine runner has a similar dynamic response behaviour of the circular disk. Therefore, in this paper the dynamic response analyses for circular disks with different dimensions and disk-blades-disk structures were carried out to better understand the fundamental dynamic behaviour for the complex turbomachinery. The influences of the pattern and number of blades were discussed in detail. © Published under licence by IOP Publishing Ltd.

  • Analysis of chatter marks damage on the Yankee dryer surface of a tissue machine

     Escaler Puigoriol, Francesc Xavier; Torre Rodriguez, Oscar de La; Egusquiza Estevez, Eduardo
    Engineering failure analysis
    Vol. 23, p. 44-54
    DOI: 10.1016/j.engfailanal.2012.02.003
    Date of publication: 2012-03-08
    Journal article

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    A tissue machine suffering from Yankee chatter marks has been experimentally investigated. A series of vibration measurements during normal operation at various Yankee speeds on both the creping and the cleaning blade holders have been carried out. The analysis in a frequency range up to 20 kHz has permitted to identify speed dependent frequency peaks and broadband high frequency vibration content on the creping zone. Hence, an experimental modal analysis of the creping blade and holder has been carried out with the machine stopped to identify its natural frequencies. As a result, resonance conditions have been identified due to the gearbox excitation originated by the meshing process. The study of the corresponding mode shapes has permitted to understand the vibration behavior and its relationship with the damage. To solve the problem, the creping blade holder structure has been redesigned to detune the resonances. Since this overhaul, comparable measurements have confirmed a significant reduction of vibrations and high frequency noise. The appearance of chatter marks has been minimized.

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    Failure investigation of a large pump-turbine runner  Open access

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Huang, Xingxing; Guardo Zabaleta, Alfredo de Jesús; Jou Santacreu, Esteban; Rodriguez, Cristian
    Engineering failure analysis
    Vol. 23, num. ., p. 27-34
    DOI: 10.1016/j.engfailanal.2012.01.012
    Date of publication: 2012-02-02
    Journal article

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  • Capability of structural-acoustical FSI numerical model to predict natural frequencies of submerged structures with nearby rigid surfaces

     RODRIGUEZ, CRISTIAN; Flores, P; Pierart, F.G.; Contzen, L.R; Egusquiza Estevez, Eduardo
    Computers and fluids
    Vol. 64, p. 117-126
    DOI: 10.1016/j.compfluid.2012.05.011
    Date of publication: 2012-07-01
    Journal article

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    Structural–acoustical model is used in industry to determine natural frequencies of runners and impellers in hydraulic turbomachinery in the stage of design. In these calculations the fluid domain is considered with comparable large distances to stationary parts while there are parts of the submerged structure (runner or impeller) that are extremely close (in relation to its thickness) to a rigid surface (hydraulic seals). These seals are not considered in the numerical model because it is assumed that structural– acoustical model is not capable to predict natural frequencies with nearby rigid surfaces. The present work builds a fluid structure interaction numerical model based on structural–acoustic coupling, checks the numerical model’s accuracy, and determines its capability to predict natural frequencies reduction due to nearby rigid surfaces comparing this model against experimental data of submerged cantilever plates. It is found that the structural–acoustical model can accurately predict the natural frequencies for submerged structures with nearby rigid surfaces with averaged absolute errors of 2.5%. This is an interesting result because it suggests that simulation of runners and impellers can be carried out considering the effect of hydraulic seals, therefore, obtaining natural frequencies that are closer to those found under operation.

  • Informe vibraciones en la válvula 4 de Susqueda-diciembre 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Castañer Rioboo, David; Presas Batllo, Alexandre
    Date: 2012-09-05
    Report

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  • Informe pruebas experimentales en funcionamiento en la Reja La Muela-Iberdrola.Sept 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen
    Date: 2012-09-10
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  • Informe on-line CH Moralets durante voladuras en la central.Febrero 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen
    Date: 2012-03-25
    Report

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  • Informe alternadores CH Guillena G1,G2 y G3 Junio 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Castañer Rioboo, David; Presas Batllo, Alexandre
    Date: 2012-06-05
    Report

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  • Memoria Predictivo 2011 UPH Ebro-Pirineos. Marzo 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Castañer Rioboo, David; Presas Batllo, Alexandre
    Date: 2012-03-10
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  • Utilització de toveres d¿Efecte Coanda per a la ventilació horitzontal de dobles façanes envidrades

     Valentín Ruiz, David; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo
    Date: 2012-10-15
    Report

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  • Memoria Predictivo 2011 UPH Sur . Mayo 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Castañer Rioboo, David; Presas Batllo, Alexandre
    Date: 2012-05-05
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  • Estudi en 2D de toveres per a la ventilació horitzontal de dobles façanes envidrades

     Valentín Ruiz, David; Guardo Zabaleta, Alfredo de Jesús; Egusquiza Estevez, Eduardo
    Date: 2012-03-20
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  • Informe pruebas experimentales-Reja La Muela-Iberdrola-Mayo 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen
    Date: 2012-05-03
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  • Informe pruebas on line banda de regulación de la CH de Cornatel.Junio 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen; Castañer Rioboo, David
    Date: 2012-06-30
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  • Analisis de vibraciones predictivo UPH Noroeste . Marzo 2012

     Egusquiza Estevez, Eduardo; Valero Ferrando, Mª Del Carmen
    Date: 2012-03-15
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  • (1882-9554) International Journal of Fluid Machinery and Systems

     Egusquiza Estevez, Eduardo
    Collaboration in journals

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  • The scientific world journal

     Egusquiza Estevez, Eduardo
    Collaboration in journals

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  • Detached eddy simulation of the rotor-stator interaction phenomenon in a moving cascade of airfoils

     Guardo Zabaleta, Alfredo de Jesús; Fontanals Garcia, Alfred; Coussirat Nuñez, Miguel Gustavo; Egusquiza Estevez, Eduardo
    IAHR Symposium on Hydraulic Machinery and Systems
    DOI: doi:10.1088/1755-1315/15/6/062039
    Presentation's date: 2012-08-23
    Presentation of work at congresses

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    The effect of cavitation on the natural frequencies of a hydrofoil  Open access

     Torre Rodriguez, Oscar de La; Escaler Puigoriol, Francesc Xavier; Egusquiza Estevez, Eduardo; Dreyer, Matthieu; Farhat, Mohamed
    International Symposium on Cavitation
    p. 1-4
    Presentation's date: 2012-08-16
    Presentation of work at congresses

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  • Dynamic response of submerged trash-racks: attachment and added mass effects

     Egusquiza Estevez, Eduardo
    IAHR Symposium on Hydraulic Machinery and Systems
    Presentation's date: 2012
    Presentation of work at congresses

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