Now showing items 1-20 of 62

    • A mechanical assembly for experiments of Saos-2 cells under vibration actuation 

      Presas Batlló, Alexandre; Deering, Joseph; Lee, Bryan; Valentín Ruiz, David; Heiss, Christian; Grandfield, Kathryn; Bosbach, Wolfram A. (2019)
      Conference report
      Restricted access - publisher's policy
      Our current experimental work investigates the influence of mechanical vibration on Saos-2 cells. We impose the vibration by using piezoelectric patches and we measure vibration response by a Laser Doppler Vibrometer. We ...
    • A novel condition monitoring methodology based on neural network of pump-turbines with extended operating range 

      Zhao, Weiqiang; Egusquiza Estévez, Eduard; Valero Ferrando, Ma. del Carmen; Egusquiza Montagut, Mònica; Valentín Ruiz, David; Presas Batlló, Alexandre (2019)
      Conference report
      Open Access
      Due to the entrance of new renewable energies, water-storage energy has to be regulated more frequently to keep the stability of power grid. Consequently, pump-turbines have to work under offdesign conditions more than ...
    • A review of pzt patches applications in submerged systems 

      Presas, Alexandre; Luo, Yongyao; Wang, Zhengwei; Valentín Ruiz, David; Egusquiza Montagut, Mònica (Multidisciplinary Digital Publishing Institute (MDPI), 2018-07-12)
      Article
      Open Access
      Submerged systems are found in many engineering, biological, and medicinal applications. For such systems, due to the particular environmental conditions and working medium, the research on the mechanical and structural ...
    • Accurate determination of the frequency response function of submerged and confined structures by using PZT-patches 

      Presas Batlló, Alexandre; Valentín Ruiz, David; Egusquiza Estévez, Eduard; Valero Ferrando, Ma. del Carmen; Egusquiza Montagut, Mònica; Bossio, Matias (2017-03-22)
      Article
      Open Access
      To accurately determine the dynamic response of a structure is of relevant interest in many engineering applications. Particularly, it is of paramount importance to determine the Frequency Response Function (FRF) for ...
    • Advanced condition monitoring of Pelton turbines 

      Egusquiza Montagut, Mònica; Valero Ferrando, Ma. del Carmen; Presas Batlló, Alexandre; Valentín Ruiz, David; Bossio, Matias; Egusquiza Estévez, Eduard (2017)
      Conference report
      Restricted access - publisher's policy
      The ability of hydropower to adapt the electricity generation to the demand is necessary to integrate wind and solar energy to the grid. Nowadays hydropower turbines are required to work under harsher operating conditions ...
    • Advanced condition monitoring of Pelton turbines 

      Egusquiza Montagut, Mònica; Egusquiza Estévez, Eduard; Valero Ferrando, Ma. del Carmen; Presas Batlló, Alexandre; Valentín Ruiz, David; Bossio, Matias (2018-04)
      Article
      Open Access
      The ability of hydropower to adapt the electricity generation to the demand is necessary to integrate wind and solar energy into the electrical grid. Nowadays, hydropower turbines are required to work under harsher operating ...
    • 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 Estévez, Eduard; Valero Ferrando, Ma. del Carmen; Alavedra, Pere (2013-09-30)
      Article
      Open Access
      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 ...
    • Behavior of Francis turbines at part load. Field assessment in prototype: Effects on power swing. 

      Valentín Ruiz, David; Presas Batlló, Alexandre; Egusquiza Montagut, Mònica; Valero Ferrando, Ma. del Carmen; Egusquiza Estévez, Eduard (Institute of Physics (IOP), 2019)
      Conference report
      Open Access
      Francis turbines are increasingly demanded to work at part load in order to satisfy the electricity generation demand and to compensate the non-constant generation of other renewable sources such as wind or solar. At part ...
    • Behavior of Francis turbines at part load. Field assessment in prototype: Effects on the hydraulic system. 

      Valero Ferrando, Ma. del Carmen; Egusquiza Montagut, Mònica; Valentín Ruiz, David; Presas Batlló, Alexandre; Egusquiza Estévez, Eduard (Institute of Physics (IOP), 2019)
      Conference report
      Open Access
      At present, hydropower plants play an important role because of their flexibility in the generation of electricity. Today, the required operating range of turbine units is expected to extend to deep part load. At part load ...
    • Combination of acoustic emission and vibratory measure-ments to characterize an ultrasonic vibration assisted ball burnishing tool for a lathe 

      Fernández Osete, Ismael; Estévez Urra, Aida; Velázquez Corral, Eric; Valentín Ruiz, David; Llumà Fuentes, Jordi; Jerez Mesa, Ramón; Travieso Rodriguez, Jose Antonio (2021-07-14)
      Article
      Open Access
      In this paper, a resonant system that produces a movement of low amplitude and ultrasonic frequency is used to achieve the vibration assistance in a ball-burnishing process. A full vibration characterization of this process ...
    • Condition monitoring of a prototype turbine. Description of the system and main results 

      Valero Ferrando, Ma. del Carmen; Egusquiza Estévez, Eduard; Presas Batlló, Alexandre; Valentín Ruiz, David; Egusquiza Montagut, Mònica; Bossio, Matias (Institute of Physics (IOP), 2017)
      Conference report
      Open Access
      The fast change in new renewable energy is affecting directly the required operating range of hydropower plants. According to the present demand of electricity, it is necessary to generate different levels of power. Because ...
    • Condition monitoring of pump-turbines. New challenges 

      Egusquiza Estévez, Eduard; Valero Ferrando, Ma. del Carmen; Valentín Ruiz, David; Presas Batlló, Alexandre; Rodriguez Godoy, Cristian (2015-05)
      Article
      Open Access
      At present, pumped storage is the only system to store huge amounts of energy. The surplus of energy in the electrical grid is used for pumping water from a lower to a higher reservoir (pump operation). At peak hours or ...
    • Detection and analysis of part load and full load instabilities in a real Francis turbine prototype 

      Presas Batlló, Alexandre; Valentín Ruiz, David; Egusquiza Estévez, Eduard; Valero Ferrando, Ma. del Carmen (Institute of Physics (IOP), 2017)
      Conference report
      Open Access
      Francis turbines operate in many cases out of its best effici ency point, in order to regulate their output power according to the instantaneous ener gy demand of the grid. Therefore, it is of paramount importance to analyse ...
    • Detection of erosive cavitation on hydraulic turbines through demodulation analysis 

      Presas Batlló, Alexandre; Luo, Yongyao; Valentín Ruiz, David; Egusquiza Montagut, Mònica; Wang, Zhengwei; Valero Ferrando, Ma. del Carmen; Egusquiza Estévez, Eduard (Institute of Physics (IOP), 2018)
      Conference report
      Open Access
      Erosive cavitation in hydraulic turbines affects severely the runner structure, increasing maintenance costs and reducing the remaining useful life of the component. Actual vibro-acoustic techniques used to detect this ...
    • Detection of hydraulic phenomena in francis turbines with different sensors 

      Valentín Ruiz, David; Presas Batlló, Alexandre; Valero Ferrando, Ma. del Carmen; Egusquiza Montagut, Mònica; Egusquiza Estévez, Eduard (Multidisciplinary Digital Publishing Institute (MDPI), 2019-09-19)
      Article
      Open Access
      Nowadays, hydropower is demanded to provide flexibility and fast response into the electrical grid in order to compensate the non-constant electricity generation of other renewable sources. Hydraulic turbines are therefore ...
    • Dynamic behaviour of a Francis turbine during voltage regulation in the electrical power system 

      Vagnoni, Elena; Valentín Ruiz, David; Avellan, François (2021-02-01)
      Article
      Open Access
      Hydroelectric units can be operated in synchronous condenser mode to provide reactive power to the electrical power system (EPS) for voltage regulation. In this operating mode, the hydraulic turbine consumes active power ...
    • Dynamic response of a rotating disk submerged and confined. Influence of the axial gap 

      Presas Batlló, Alexandre; Valentín Ruiz, David; Egusquiza Estévez, Eduard; Valero Ferrando, Ma. del Carmen; Seidel, Ulrich (2016-04-01)
      Article
      Open Access
      In this paper, the natural frequencies and mode shapes of a rotating disk submerged and totally confined inside a rigid casing, have been obtained. These have been calculated analytically, numerically and experimentally ...
    • Dynamic response of Pelton runners: Numerical and experimental analysis in prototypes 

      Egusquiza Montagut, Mònica; Valentín Ruiz, David; Presas Batlló, Alexandre; Egusquiza Estévez, Eduard (Elsevier, 2020-09-01)
      Article
      Restricted access - publisher's policy
      Worldwide electricity generation is featured by the growth of intermittent renewable energies. In this context, hydropower plays a fundamental role because it provides flexibility to the power grid and ensures its stability. ...
    • Dynamic response of the MICA runner. Experiment and simulation 

      Valentín Ruiz, David; Presas Batlló, Alexandre; Egusquiza Estévez, Eduard; Valero Ferrando, Ma. del Carmen; Bossio, Matias (Institute of Physics (IOP), 2017)
      Conference report
      Open Access
      Studying the dynamic response of Francis turbine runners is of paramount importance in order to avoid resonance problems during operating conditions. For this purpose, the natural frequencies as well as their associated ...
    • Experimental analysis of the dynamic behavior of a rotating disk submerged in water 

      Presas Batlló, Alexandre; Valentín Ruiz, David; Egusquiza Estévez, Eduard; Valero Ferrando, Ma. del Carmen; Seidel, Ulrich (2014)
      Conference report
      Open Access
      To study the dynamic behavior of turbine runners (natural frequencies and mode shapes) not only the added mass effect of still water has to be considered. Also the effect of rotation may not be neglected in the dynamic ...