http://hdl.handle.net/2117/3251 Thu, 20 Jun 2013 01:25:58 GMT 2013-06-20T01:25:58Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/18852 Title: Analysis of the dynamic response of pump-turbine runners. Part I: Experiment Authors: Presas Batlló, Alexandre; Valero Ferrando, M.del Carmen; Huang, Xingxing; Egusquiza Estévez, Eduard; Farhat, Mohamed; Avellan, François Abstract: When in operation, pump-turbine runners have to withstand large pressure pulsations generated by the rotor-stator interaction. The analysis of the dynamic behavior of these structures is necessary to avoid damage. For this analysis a realistic model of the runner is necessary. When the runner is submerged in water and inside the casing, its dynamic response is greatly affected. The added mass effects of the surrounding fluid and the proximity of the head-cover and bottom-cover may reduce the natural frequencies. The frequency reduction produced by the added mass effects and the influence of the boundary conditions has to be known for a safe design of the runner. In this paper an experimental investigation on the dynamic response of a model runner is presented. A reduced scale model of a pump-turbine was tested outside and inside the casing with different boundary conditions. For the excitation of the runner at different frequencies piezoelectric patches were used. The response was measured with miniature accelerometers located in several positions inside the runner. From the measurements the natural frequencies and mode-shapes of the runner were calculated using EMA. The influence of the added mass and of the boundary conditions is presented and discussed. Wed, 17 Apr 2013 12:02:49 GMT http://hdl.handle.net/2117/18852 2013-04-17T12:02:49Z Presas Batlló, Alexandre; Valero Ferrando, M.del Carmen; Huang, Xingxing; Egusquiza Estévez, Eduard; Farhat, Mohamed; Avellan, François no When in operation, pump-turbine runners have to withstand large pressure pulsations generated by the rotor-stator interaction. The analysis of the dynamic behavior of these structures is necessary to avoid damage. For this analysis a realistic model of the runner is necessary. When the runner is submerged in water and inside the casing, its dynamic response is greatly affected. The added mass effects of the surrounding fluid and the proximity of the head-cover and bottom-cover may reduce the natural frequencies. The frequency reduction produced by the added mass effects and the influence of the boundary conditions has to be known for a safe design of the runner. In this paper an experimental investigation on the dynamic response of a model runner is presented. A reduced scale model of a pump-turbine was tested outside and inside the casing with different boundary conditions. For the excitation of the runner at different frequencies piezoelectric patches were used. The response was measured with miniature accelerometers located in several positions inside the runner. From the measurements the natural frequencies and mode-shapes of the runner were calculated using EMA. The influence of the added mass and of the boundary conditions is presented and discussed. http://hdl.handle.net/2117/18787 Title: PM21 Vibraciones Crepado Marzo 2011-Marzo 2013 Authors: Escaler Puigoriol, Francesc Xavier Mon, 15 Apr 2013 10:20:20 GMT http://hdl.handle.net/2117/18787 2013-04-15T10:20:20Z Escaler Puigoriol, Francesc Xavier no http://hdl.handle.net/2117/18433 Title: Experimental investigation of added mass effects on a hydrofoil under cavitation conditions Authors: Torre Rodríguez, Óscar de la; Escaler Puigoriol, Francesc Xavier; Egusquiza Estévez, Eduard; Farhat, Mohamed Abstract: 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. Wed, 20 Mar 2013 11:33:13 GMT http://hdl.handle.net/2117/18433 2013-03-20T11:33:13Z Torre Rodríguez, Óscar de la; Escaler Puigoriol, Francesc Xavier; Egusquiza Estévez, Eduard; Farhat, Mohamed no 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. http://hdl.handle.net/2117/17901 Title: Numerical and experimental analysis of the dynamic response of large submerged trash-racks Authors: Huang, Xingxing; Valero Ferrando, M.del Carmen; Egusquiza Estévez, Eduard; Presas Batlló, Alexandre; Guardo Zabaleta, Alfredo de Jesús Abstract: 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. Thu, 21 Feb 2013 08:58:02 GMT http://hdl.handle.net/2117/17901 2013-02-21T08:58:02Z Huang, Xingxing; Valero Ferrando, M.del Carmen; Egusquiza Estévez, Eduard; Presas Batlló, Alexandre; Guardo Zabaleta, Alfredo de Jesús no 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. http://hdl.handle.net/2117/17894 Title: Analysis if the dynamic response of pump-turbine runners- Part I: Experiment Authors: Presas Batlló, Alexandre; Valero Ferrando, M.del Carmen; Egusquiza Estévez, Eduard; Huang, Xingxing; Farhat, Mohamed; Avellan, François Abstract: When in operation, pump-turbine runners have to withstand large pressure pulsations generated by the rotor-stator interaction. The analysis of the dynamic behavior of these structures is necessary to avoid damage. For this analysis a realistic model of the runner is necessary. When the runner is submerged in water and inside the casing, its dynamic response is greatly affected. The added mass effects of the surrounding fluid and the proximity of the head-cover and bottom-cover may reduce the natural frequencies. The frequency reduction produced by the added mass effects and the influence of the boundary conditions has to be known for a safe design of the runner. In this paper an experimental investigation on the dynamic response of a model runner is presented. A reduced scale model of a pump-turbine was tested outside and inside the casing with different boundary conditions. For the excitation of the runner at different frequencies piezoelectric patches were used. The response was measured with miniature accelerometers located in several positions inside the runner. From the measurements the natural frequencies and mode-shapes of the runner were calculated using EMA. The influence of the added mass and of the boundary conditions is presented and discussed. Wed, 20 Feb 2013 11:36:21 GMT http://hdl.handle.net/2117/17894 2013-02-20T11:36:21Z Presas Batlló, Alexandre; Valero Ferrando, M.del Carmen; Egusquiza Estévez, Eduard; Huang, Xingxing; Farhat, Mohamed; Avellan, François no When in operation, pump-turbine runners have to withstand large pressure pulsations generated by the rotor-stator interaction. The analysis of the dynamic behavior of these structures is necessary to avoid damage. For this analysis a realistic model of the runner is necessary. When the runner is submerged in water and inside the casing, its dynamic response is greatly affected. The added mass effects of the surrounding fluid and the proximity of the head-cover and bottom-cover may reduce the natural frequencies. The frequency reduction produced by the added mass effects and the influence of the boundary conditions has to be known for a safe design of the runner. In this paper an experimental investigation on the dynamic response of a model runner is presented. A reduced scale model of a pump-turbine was tested outside and inside the casing with different boundary conditions. For the excitation of the runner at different frequencies piezoelectric patches were used. The response was measured with miniature accelerometers located in several positions inside the runner. From the measurements the natural frequencies and mode-shapes of the runner were calculated using EMA. The influence of the added mass and of the boundary conditions is presented and discussed. http://hdl.handle.net/2117/17766 Title: Numerical and experimental analysis of the dynamic response of large submerged trash-racks Authors: Huang, Xingxing; Valero Ferrando, M.del Carmen; Egusquiza Estévez, Eduard; Presas Batlló, Alexandre; Guardo Zabaleta, Alfredo de Jesús Abstract: 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. Thu, 14 Feb 2013 13:58:52 GMT http://hdl.handle.net/2117/17766 2013-02-14T13:58:52Z Huang, Xingxing; Valero Ferrando, M.del Carmen; Egusquiza Estévez, Eduard; Presas Batlló, Alexandre; Guardo Zabaleta, Alfredo de Jesús no 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. http://hdl.handle.net/2117/17764 Title: Capability of structural-acoustical FSI numerical model to predict natural frequencies of submerged structures with nearby rigid surfaces Authors: Rodríguez, Cristian; Flores, P.; Pierart, F.G.; Contzen, L.R.; Egusquiza Estévez, Eduard Abstract: 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. Thu, 14 Feb 2013 13:08:40 GMT http://hdl.handle.net/2117/17764 2013-02-14T13:08:40Z Rodríguez, Cristian; Flores, P.; Pierart, F.G.; Contzen, L.R.; Egusquiza Estévez, Eduard no 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. http://hdl.handle.net/2117/17760 Title: PM21 Creping & Cleaning Vibrations May-June 2012 Authors: Escaler Puigoriol, Francesc Xavier Thu, 14 Feb 2013 12:03:58 GMT http://hdl.handle.net/2117/17760 2013-02-14T12:03:58Z Escaler Puigoriol, Francesc Xavier no http://hdl.handle.net/2117/17748 Title: The effect of cavitation on the natural frequencies of a hydrofoil Authors: Torre Rodríguez, Óscar de la; Escaler Puigoriol, Francesc Xavier; Egusquiza Estévez, Eduard; Dreyer, Matthieu; Farhat, Mohamed Thu, 14 Feb 2013 09:23:34 GMT http://hdl.handle.net/2117/17748 2013-02-14T09:23:34Z Torre Rodríguez, Óscar de la; Escaler Puigoriol, Francesc Xavier; Egusquiza Estévez, Eduard; Dreyer, Matthieu; Farhat, Mohamed no http://hdl.handle.net/2117/17743 Title: Estudio preliminar del comportamiento vibratorio de los aerogeneradores 9, 30 y 44 Authors: Escaler Puigoriol, Francesc Xavier Wed, 13 Feb 2013 18:29:33 GMT http://hdl.handle.net/2117/17743 2013-02-13T18:29:33Z Escaler Puigoriol, Francesc Xavier no http://hdl.handle.net/2117/17739 Title: Cavitation intensity measured on a Naca 0015 hydrofoil with various gas contents Authors: Ekanger, Jarle V.; Kjeldsen, Morten; Escaler Puigoriol, Francesc Xavier; Kawakami, Ellison; Arndt, Roger E. A. Wed, 13 Feb 2013 17:52:20 GMT http://hdl.handle.net/2117/17739 2013-02-13T17:52:20Z Ekanger, Jarle V.; Kjeldsen, Morten; Escaler Puigoriol, Francesc Xavier; Kawakami, Ellison; Arndt, Roger E. A. no http://hdl.handle.net/2117/17729 Title: Failure investigation of a large pump-turbine runner Authors: Egusquiza Estévez, Eduard; Valero Ferrando, M.del Carmen; Huang, Xingxing; Guardo Zabaleta, Alfredo de Jesús; Jou Santacreu, Esteban; Rodríguez, Cristian Wed, 13 Feb 2013 15:03:40 GMT http://hdl.handle.net/2117/17729 2013-02-13T15:03:40Z Egusquiza Estévez, Eduard; Valero Ferrando, M.del Carmen; Huang, Xingxing; Guardo Zabaleta, Alfredo de Jesús; Jou Santacreu, Esteban; Rodríguez, Cristian no http://hdl.handle.net/2117/17728 Title: PM21 Creping & Cleaning Vibrations January-February 2012 Authors: Escaler Puigoriol, Francesc Xavier Wed, 13 Feb 2013 14:49:01 GMT http://hdl.handle.net/2117/17728 2013-02-13T14:49:01Z Escaler Puigoriol, Francesc Xavier no http://hdl.handle.net/2117/17724 Title: Desarrollo de conocimiento para la mejora del mantenimiento predictivo en el sector eólico Authors: Escaler Puigoriol, Francesc Xavier Wed, 13 Feb 2013 14:35:16 GMT http://hdl.handle.net/2117/17724 2013-02-13T14:35:16Z Escaler Puigoriol, Francesc Xavier no http://hdl.handle.net/2117/17697 Title: Informe preliminar de las curvas de potencia de las turbinas de SJB Authors: Escaler Puigoriol, Francesc Xavier Wed, 13 Feb 2013 09:00:36 GMT http://hdl.handle.net/2117/17697 2013-02-13T09:00:36Z Escaler Puigoriol, Francesc Xavier no