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Prof. Xavier Escaler
Universitat Politècnica de Catalunya - Barcelona Tech

Basic Info


Research Keywords & Expertise

0 Cavitation
0 Computational Fluid Dynamics (CFD)
0 Experimental Analysis
0 Flow Control
0 Cavitation erosion

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Cavitation
Fluid and Structure Interaction
Cavitation erosion
Experimental Analysis

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Short Biography

Xavier Escaler is Associate Professor at the Fluid Mechanics Department of UP. He is currently responsible for the Barcelona Fluids & Energy Lab, devoted to advancement and innovation in the field of renewable energy. His activities include lecturing, research, technology transfer, and management. He has participated in a number of competitive research projects and contracts with industry, comprising the measurement of flows and structures in hydraulic systems and machines, the diagnostics of dynamic fluid problems, the use of CFD for the numerical simulation of cavitation and coupled fluid-structure systems, the modelling of piping systems, and the on-line and off-line monitoring of rotating machines for predictive maintenance and condition monitoring.

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Journal article
Published: 22 June 2021 in Sensors
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The present paper assesses the performance and characteristics of fiber Bragg grating sensors, with a special interest in their applications in hydraulic machinery and systems. The hydropower industry is turning to this technology with high expectations of obtaining high quality data to validate and calibrate numerical models that could be used as digital twins of key assets, further strengthening the sector’s relevant position within industry 4.0. Prior to any validation, fiber Bragg grating sensors’ ability to perform well underwater for long periods of time with minimal degradation, and their ease of scalability, drew the authors´ attention. A simplified modal analysis of a partially submerged beam is proposed here as a first step to validate the potential of this type of technology for hydropower applications. Fiber Bragg grating sensors are used to obtain the beam’s natural frequencies and to damp vibrations under different conditions. The results are compared with more established waterproof electric strain gauges and a laser vibrometer with good agreement. The presence of several sensors in a single fiber ensures high spatial resolution, fundamental to precisely determine vibration patterns, which is a main concern in this industry. In this work, the beam’s vibration patterns have been successfully captured under different excitations and conditions.

ACS Style

Oscar de la Torre; Ignazio Floris; Salvador Sales; Xavier Escaler. Fiber Bragg Grating Sensors for Underwater Vibration Measurement: Potential Hydropower Applications. Sensors 2021, 21, 4272 .

AMA Style

Oscar de la Torre, Ignazio Floris, Salvador Sales, Xavier Escaler. Fiber Bragg Grating Sensors for Underwater Vibration Measurement: Potential Hydropower Applications. Sensors. 2021; 21 (13):4272.

Chicago/Turabian Style

Oscar de la Torre; Ignazio Floris; Salvador Sales; Xavier Escaler. 2021. "Fiber Bragg Grating Sensors for Underwater Vibration Measurement: Potential Hydropower Applications." Sensors 21, no. 13: 4272.

Conference paper
Published: 01 June 2021 in IOP Conference Series: Earth and Environmental Science
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The transient cavitating flow in the wake of a hydrofoil at zero incidence angle has been simulated using a homogeneous mixture cavitation mass transfer model combined with both Reynolds Average Navier-Stokes (RANS) and Scale Resolving Simulation (SRS) turbulence models. The hydrofoil geometry corresponds to a 2D NACA 0009 with a truncated trailing edge which has already been extensively investigated in the High-Speed Cavitation Tunnel of the EPFL. The hydrodynamic conditions of interest correspond to a free stream velocity of 20 m/s (Re = 2 106) without cavitation and with two different degrees of cavitation. To improve the prediction of the vortex shedding behing the hydrofoil, the γ − Rθt transitional boundary layer model has been coupled with the turbulence models. At cavitation-free regime, all the turbulence models with the exception of the SST and LES WALE ones have the ability to predict the experimentally measured vortex shedding frequency. Nevertheless, the results indicate that, neither the SST nor the DES-SST γ − Rθt, can predict the vortex shedding frequency increase which has been experimentally observed when cavitation occurs. In contrast, the numerical results provided by the SST γ − Rθt and the SSTCC γ − Rθt show the capability to predict the expected shedding frequencies for both non cavitation and cavitation conditions. Beyond all expectation, the results provided by the LES WALE seem not only to overestimate the vortex shedding frequency at cavitation free conditions but also to underestimate the frequency when the cavitation number is significantly reduced.

ACS Style

Jian Chen; Linlin Geng; Oscar De La Torre; Xavier Escaler. Assessment of turbulence models for the prediction of Bénard-Von Kármán vortex shedding behind a truncated hydrofoil in cavitation conditions. IOP Conference Series: Earth and Environmental Science 2021, 774, 012025 .

AMA Style

Jian Chen, Linlin Geng, Oscar De La Torre, Xavier Escaler. Assessment of turbulence models for the prediction of Bénard-Von Kármán vortex shedding behind a truncated hydrofoil in cavitation conditions. IOP Conference Series: Earth and Environmental Science. 2021; 774 (1):012025.

Chicago/Turabian Style

Jian Chen; Linlin Geng; Oscar De La Torre; Xavier Escaler. 2021. "Assessment of turbulence models for the prediction of Bénard-Von Kármán vortex shedding behind a truncated hydrofoil in cavitation conditions." IOP Conference Series: Earth and Environmental Science 774, no. 1: 012025.

Journal article
Published: 21 November 2020 in Fluids
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Vortex cavitation can appear in the wake flow of hydrofoils, inducing unwanted consequences such as vibrations or unstable behaviors in hydraulic machinery and systems. To investigate the cavitation effects on hydrofoil vortex shedding, a numerical investigation of the flow around a 2D NACA0009 with a blunt trailing edge at free caviation conditions and at two degrees of cavitation developments has been carried out by means of the Zwart cavitation model and the LES WALE turbulence model which permits predicting the laminar to turbulent transition of the boundary layers. To analyze the dynamic behavior of the vortex shedding process and the coherent structures, two identification methods based on the Eulerian and Lagrangian reference frames have been applied to the simulated unsteady flow field. It is found that the cavitation occurrence in the wake significantly changes the main vortex shedding characteristics including the morphology of the vortices, the vortex formation length, the effective height of the near wake flow and the shedding frequency. The numerical results predict that the circular shape of the vortices changes to an elliptical one and that the vortex shedding frequency is significantly increased under cavitation conditions. The main reason for the frequency increase seems to be the reduction in the transverse separation between the upper and lower rows of vortices induced by the increase in the vortex formation length.

ACS Style

Jian Chen; Linlin Geng; Xavier Escaler. Numerical Investigation of the Cavitation Effects on the Vortex Shedding from a Hydrofoil with Blunt Trailing Edge. Fluids 2020, 5, 218 .

AMA Style

Jian Chen, Linlin Geng, Xavier Escaler. Numerical Investigation of the Cavitation Effects on the Vortex Shedding from a Hydrofoil with Blunt Trailing Edge. Fluids. 2020; 5 (4):218.

Chicago/Turabian Style

Jian Chen; Linlin Geng; Xavier Escaler. 2020. "Numerical Investigation of the Cavitation Effects on the Vortex Shedding from a Hydrofoil with Blunt Trailing Edge." Fluids 5, no. 4: 218.

Journal article
Published: 28 July 2020 in Applied Sciences
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A numerical investigation of the erosion aggressiveness of leading edge unsteady cloud cavitation based on the energy balance approach has been carried out to ascertain the main damaging mechanisms and the influence of the free stream flow velocity. A systematic approach has permitted the determination of the influence of several parameters on the spatial and temporal distribution of the erosion results comprising the selection of the cavitation model and the collapse driving pressure. In particular, the Zwart, Sauer and Kunz cavitation models have been compared as well as the use of instantaneous versus average pressure values. The numerical results have been compared against a series of experimental results obtained from pitting tests on copper and stainless steel specimens. Several cavitation erosion indicators have been defined and their accuracy to predict the experimental observations has been assessed and confirmed when using a material-dependent damaging threshold level. In summary, the use of the average pressure levels during a sufficient number of simulated shedding cycles combined with the Sauer cavitation model are the recommended parameters to achieve reliable results that reproduce the main erosion mechanisms found in cloud cavitation. Moreover, the proposed erosion indicators follow a power law as a function of the free stream flow velocity with exponents ranging from 3 to 5 depending on their definition.

ACS Style

Linlin Geng; Jian Chen; Oscar De La Torre; Xavier Escaler. Numerical Simulation of Cavitation Erosion Aggressiveness Induced by Unsteady Cloud Cavitation. Applied Sciences 2020, 10, 5184 .

AMA Style

Linlin Geng, Jian Chen, Oscar De La Torre, Xavier Escaler. Numerical Simulation of Cavitation Erosion Aggressiveness Induced by Unsteady Cloud Cavitation. Applied Sciences. 2020; 10 (15):5184.

Chicago/Turabian Style

Linlin Geng; Jian Chen; Oscar De La Torre; Xavier Escaler. 2020. "Numerical Simulation of Cavitation Erosion Aggressiveness Induced by Unsteady Cloud Cavitation." Applied Sciences 10, no. 15: 5184.

Journal article
Published: 03 June 2020 in European Journal of Mechanics - B/Fluids
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The current study evaluates the effect of taking into account the second order term of the Rayleigh–Plesset equation for the numerical simulation of cavitation with homogeneous mixture models. For that, the corrected expression for the condensation mass transfer rate has been mathematically derived and implemented in the original Zwart and Singhal cavitation models. Two tests cases of steady sheet cavitation around a NACA 0009 hydrofoil and a hemi-spherical body at different cavitation coefficients have been simulated with both the original and the corrected models. The results demonstrate that the pressure distribution at the closure region of the attached cavity is better predicted and a stronger pressure gradient is obtained. Consequently, the cavity length is slightly shortened and it gets closer to the experimental observations. Another test case of cloud cavitation around a NACA 0009 hydrofoil has confirmed that the prediction of the shedding frequency is also improved with the corrected Zwart model because the maximum cavity length is significantly reduced. In conclusion, the proposed modification of the Zwart and Singhal cavitation models helps to ameliorate the numerical simulation of both steady and unsteady cavitation flows.

ACS Style

Linlin Geng; Jian Chen; Xavier Escaler. Improvement of cavitation mass transfer modeling by including Rayleigh–Plesset​ equation second order term. European Journal of Mechanics - B/Fluids 2020, 84, 313 -324.

AMA Style

Linlin Geng, Jian Chen, Xavier Escaler. Improvement of cavitation mass transfer modeling by including Rayleigh–Plesset​ equation second order term. European Journal of Mechanics - B/Fluids. 2020; 84 ():313-324.

Chicago/Turabian Style

Linlin Geng; Jian Chen; Xavier Escaler. 2020. "Improvement of cavitation mass transfer modeling by including Rayleigh–Plesset​ equation second order term." European Journal of Mechanics - B/Fluids 84, no. : 313-324.

Articles
Published: 26 November 2019 in Engineering Applications of Computational Fluid Mechanics
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The numerical simulation of unsteady cavitation flows is sensitive to the selected models and associated parameters. Consequently, three Reynolds Average Navier-Stokes (RANS) turbulence models and the Zwart cavitation model were selected to assess their performance for the simulation of cloud cavitation on 2D hydrofoils. The experimental cavitation tests from a NACA65012 hydrofoil at different hydrodynamic conditions were used as a reference to tune the modeling parameters and the experimental tests from a NACA0015 were finally used to validate them. The effects of near wall grid refinement, time step, iterations and mesh elements were also investigated. The results indicate that the Shear Stress Transport (SST) model is sensitive to near wall grid resolution which should be fine enough. Moreover, the cavitation morphology and dynamic behavior are sensitive to the selection of the Zwart empirical vaporization, Fv, and condensation, Fc, coefficients. Therefore, a multiple linear regression approach with the single objective of predicting the shedding frequency was carried out that permitted to find the range of coefficient values giving the most accurate results. In addition, it was observed that they provided a better prediction of the vapor volume fraction and of the instantaneous pressure pulse generated by the main cloud cavity collapse.

ACS Style

Linlin Geng; Xavier Escaler. Assessment of RANS turbulence models and Zwart cavitation model empirical coefficients for the simulation of unsteady cloud cavitation. Engineering Applications of Computational Fluid Mechanics 2019, 14, 151 -167.

AMA Style

Linlin Geng, Xavier Escaler. Assessment of RANS turbulence models and Zwart cavitation model empirical coefficients for the simulation of unsteady cloud cavitation. Engineering Applications of Computational Fluid Mechanics. 2019; 14 (1):151-167.

Chicago/Turabian Style

Linlin Geng; Xavier Escaler. 2019. "Assessment of RANS turbulence models and Zwart cavitation model empirical coefficients for the simulation of unsteady cloud cavitation." Engineering Applications of Computational Fluid Mechanics 14, no. 1: 151-167.

Journal article
Published: 05 September 2019 in Applied Sciences
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The present paper focuses on the numerical simulation of unsteady cavitation around a NACA66 hydrofoil to improve the understanding of the cavitation effects on hydraulic machinery. For this aim, the Zwart–Gerber–Belamri cavitation model was updated and uploaded as a library file for OpenFOAM’s solvers using C++ language. Furthermore, the hybrid Reynold average Navier–Stokes (RANS)–large eddy simulation (LES) model k - ω SST scale adaptive simulation (SAS) was implemented as a turbulence model for the present study of scale adaptive simulation. For validation, numerical results were compared with experimental results obtained by Leroux at the Naval Academy Research Institute in France. In order to highlight the benefits in terms of computational consumption and reproduction of the phenomenon the k - ω SST SAS model was compared against implicit large eddy simulation (ILES). Results show that the cavitation evolution including the maximum vapor length, the detachment and the oscillation frequency were reproduced satisfactorily using k - ω SST SAS. Moreover, k - ω SST SAS results predicted a lower total vapor volume on time than ILES, which is related to observed pulses of pressure coefficient, C p , and those match fairly well with the experimental results. To summarize, the k - ω SST SAS model predicts with good accuracy unsteady cavitation behavior around hydrofoils and shows improved versatility over the ILES approach.

ACS Style

Víctor Hidalgo; Xavier Escaler; Esteban Valencia; Xiaoxing Peng; José Erazo; Diana Puga; Xianwu Luo. Scale-Adaptive Simulation of Unsteady Cavitation Around a Naca66 Hydrofoil. Applied Sciences 2019, 9, 3696 .

AMA Style

Víctor Hidalgo, Xavier Escaler, Esteban Valencia, Xiaoxing Peng, José Erazo, Diana Puga, Xianwu Luo. Scale-Adaptive Simulation of Unsteady Cavitation Around a Naca66 Hydrofoil. Applied Sciences. 2019; 9 (18):3696.

Chicago/Turabian Style

Víctor Hidalgo; Xavier Escaler; Esteban Valencia; Xiaoxing Peng; José Erazo; Diana Puga; Xianwu Luo. 2019. "Scale-Adaptive Simulation of Unsteady Cavitation Around a Naca66 Hydrofoil." Applied Sciences 9, no. 18: 3696.

Journal article
Published: 17 June 2019 in Journal of Vibration and Acoustics
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High-speed water tunnels are typically used to investigate the single-phase and two-phase flows around hydrofoils for hydraulic machinery applications but their dynamic behavior is not usually evaluated. The modal analysis of an NACA0009 hydrofoil inside the test section was calculated with a coupled acoustic fluid–structure model, which shows a good agreement with the experimental results. This numerical model has been used to study the influence on the hydrofoil modes of vibration of the acoustic properties of the surrounding fluid and of the tunnel test section dimensions. It has been found that the natural frequencies of the acoustic domain are inversely proportional to the test section dimensions. Moreover, these acoustic frequencies decrease linearly with the reduction of the speed of sound in the fluid medium. However, the hydrofoil frequencies are not affected by the change of the speed of sound except when they match an acoustic frequency. If both mode shapes are similar, a strong coupling occurs and the hydrofoil vibration follows the linear reduction of natural frequency induced by the acoustic mode. If both mode shapes are dissimilar, a new mode appears whose frequency decreases linearly with speed of sound while keeping the acoustic mode of vibration. This new fluid–structure mode of vibration appears in between two hydrofoil structure modes and its evolution with sound speed reduction has been called “mode transition.” Overall, these findings reinforce the idea that fluid–structure interaction effects must be taken into account when studying the induced vibrations on hydrofoils inside water tunnels.

ACS Style

Wei Wang; Lingjiu Zhou; Zhengwei Wang; Xavier Escaler; Oscar De La Torre. Numerical Investigation Into the Influence on Hydrofoil Vibrations of Water Tunnel Test Section Acoustic Modes. Journal of Vibration and Acoustics 2019, 141, 051015 -23.

AMA Style

Wei Wang, Lingjiu Zhou, Zhengwei Wang, Xavier Escaler, Oscar De La Torre. Numerical Investigation Into the Influence on Hydrofoil Vibrations of Water Tunnel Test Section Acoustic Modes. Journal of Vibration and Acoustics. 2019; 141 (5):051015-23.

Chicago/Turabian Style

Wei Wang; Lingjiu Zhou; Zhengwei Wang; Xavier Escaler; Oscar De La Torre. 2019. "Numerical Investigation Into the Influence on Hydrofoil Vibrations of Water Tunnel Test Section Acoustic Modes." Journal of Vibration and Acoustics 141, no. 5: 051015-23.

Journal article
Published: 11 June 2019 in Fluids
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To have a safe structural design, an analysis of the dynamic behavior of a Francis turbine runner with consideration of the added mass effects of surrounding water is necessary during design phase. Both in design and at off-design operations, large-scale forms of attached cavitation may appear on runner blades and can change the added mass effects of the surrounding fluid in relation to a single water domain. Consequently, a numerical investigation of the modal response of a Francis runner has been carried out by reproducing the presence of various sizes of leading edge cavitation (LEC) and trailing edge cavitation (TEC). The fluid–structure interaction problem has been solved by means of an acoustic-structural coupling method. The calculated added mass effects with cavitation have been compared with those corresponding to the pure water condition without cavitation. Firstly, a single blade has been investigated to evaluate the level of significance for the proposed cavity shapes and dimensions. Afterwards, based on the results obtained, the complete runner structure has been considered, factoring in similar cavity shapes and locations. The results prove that significant added mass effects are induced on the entire runner by the attached cavitation that increase the natural frequencies of the first modes. Moreover, the added mass effects increase with cavity size and amplitude of blade deformation below the cavity.

ACS Style

Xingxing Huang; Xavier Escaler. Added Mass Effects on a Francis Turbine Runner with Attached Blade Cavitation. Fluids 2019, 4, 107 .

AMA Style

Xingxing Huang, Xavier Escaler. Added Mass Effects on a Francis Turbine Runner with Attached Blade Cavitation. Fluids. 2019; 4 (2):107.

Chicago/Turabian Style

Xingxing Huang; Xavier Escaler. 2019. "Added Mass Effects on a Francis Turbine Runner with Attached Blade Cavitation." Fluids 4, no. 2: 107.

Journal article
Published: 09 May 2019 in Energies
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It has been found recently that the dynamic behavior of a cavitating hydrofoil is different from that in pure water in that, not only are the natural frequencies different, but the mode shapes may also change. In order to elucidate the mechanism behind this phenomenon, finite element simulations were carried out based on acoustic–structure coupling equations. It was found that the structure and acoustic modes exhibit mode transitions with the variation of the sound speed in the cavity. Further, the mode transition was caused by coupling of the structure with the acoustic modes, which was induced by the vapor mode. The amplitude of the vibration near the mode transition point was high and the mode shape was easily excited. Moreover, with the change of the sound speed in the cavity, the different distributions of the acoustic pressure mode resulted in different structure mode shapes, even on the same transition line. Considering this, a sheet cavitation was simulated by a small change of the void fraction to 0.999 and the sound speed from 343 to 275 m/s to obtain good agreement with the experimental data. Both results showed that the second bending mode under cavitation conditions became a bending–torsion coupled mode.

ACS Style

Wei Wang; Lingjiu Zhou; Zhengwei Wang; Xavier Escaler; Oscar De La Torre. Numerical Investigation into the Effect of Sound Speed in Attached Cavitation on Hydrofoil Modes of Vibration. Energies 2019, 12, 1758 .

AMA Style

Wei Wang, Lingjiu Zhou, Zhengwei Wang, Xavier Escaler, Oscar De La Torre. Numerical Investigation into the Effect of Sound Speed in Attached Cavitation on Hydrofoil Modes of Vibration. Energies. 2019; 12 (9):1758.

Chicago/Turabian Style

Wei Wang; Lingjiu Zhou; Zhengwei Wang; Xavier Escaler; Oscar De La Torre. 2019. "Numerical Investigation into the Effect of Sound Speed in Attached Cavitation on Hydrofoil Modes of Vibration." Energies 12, no. 9: 1758.

Journal article
Published: 07 December 2018 in Machines
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A sample of healthy wind turbines from the same wind farm with identical sizes and designs was investigated to determine the average vibrational signatures of the drive train components during normal operation. The units were variable-speed machines with three blades. The rotor was supported by two bearings, and the drive train connected to an intermediate three-stage planetary/helical gearbox. The nominal 2 MW output power was regulated using blade pitch adjustment. Vibrations were measured in exactly the same positions using the same type of sensors over a six-month period covering the entire range of operating conditions. The data set was preliminary validated to remove outliers based on the theoretical power curves. The most relevant frequency peaks in the rotor, gearbox, and generator vibrations were detected and identified based on averaged power spectra. The amplitudes of the peaks induced by a common source of excitation were compared in different measurement positions. A wind speed dependency of broadband vibration amplitudes was also observed. Finally, a fault detection case is presented showing the change of vibration signature induced by a damage in the gearbox.

ACS Style

Xavier Escaler; Toufik Mebarki. Full-Scale Wind Turbine Vibration Signature Analysis. Machines 2018, 6, 63 .

AMA Style

Xavier Escaler, Toufik Mebarki. Full-Scale Wind Turbine Vibration Signature Analysis. Machines. 2018; 6 (4):63.

Chicago/Turabian Style

Xavier Escaler; Toufik Mebarki. 2018. "Full-Scale Wind Turbine Vibration Signature Analysis." Machines 6, no. 4: 63.

Journal article
Published: 10 August 2018 in Journal of Fluids and Structures
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In this study, experimental and numerical analyses were performed to determine the effects of water loading on the axisymmetric modes of vibration of a circular plate. The plate was harmonically excited at its centre through an extension bar and its outer edge was left free. The Chladni technique, which involves exciting the plate at a resonance and waiting for sand grains sprinkled on the plate to collect along the nodal circles, was used to identify and visualize the modes both in air and fully submerged in water. Surprisingly, inverse Chladni patterns were observed in water as particles were drawn towards the zero transversal velocity radii by the induced flow. A coupled acoustic–structural finite element model was built to simulate the same modes, which had been preliminarily validated against theoretical results of a completely free edged plate. A good agreement between experimental and numerical natural frequencies and mode shapes was found. The frequency reduction ratio due to the added mass effect was around 64 %. Moreover, measurable differences due to fluid–structure coupling were observed in the radii of the nodal circles between corresponding dry and wet modes.

ACS Style

Xavier Escaler; Oscar De La Torre. Axisymmetric vibrations of a circular Chladni plate in air and fully submerged in water. Journal of Fluids and Structures 2018, 82, 432 -445.

AMA Style

Xavier Escaler, Oscar De La Torre. Axisymmetric vibrations of a circular Chladni plate in air and fully submerged in water. Journal of Fluids and Structures. 2018; 82 ():432-445.

Chicago/Turabian Style

Xavier Escaler; Oscar De La Torre. 2018. "Axisymmetric vibrations of a circular Chladni plate in air and fully submerged in water." Journal of Fluids and Structures 82, no. : 432-445.

Proceedings article
Published: 16 July 2017 in Volume 1A: Codes and Standards
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The ALBA Synchrotron Light Source in Barcelona (Spain) requires a reliable, stable and adequate cooling system for its optimal operation. The current design with four long and intricate consumption lines with a ring type piping layout (270 m perimeter) and a common return pipe is believed to compromise the operability and to promote the trapping of air pockets. In order to improve its performance, a better understanding of the thermo-fluid dynamic behaviour is required that permits to opmitize the system and to anticipate unexpected failures. For that, a detailed 1D model has been built with Flowmaster® software comprising all the components and the various regulation mechanisms to control fluid temperature and pressure. Preliminarily, the model has been validated in steady state operating conditions against experimental measurements showing good agreement. Then, a series of specific steady and transient numerical simulations have been carried out to determine the system response. In particular, the effects of blockage and leakage as well as the increase or decrease of heat duty have been analysed. Furthermore, the best flow distribution through the rings has also been found to reduce the air content by maximizing the velocities.

ACS Style

Xavier Escaler; Montserrat Prieto; Marcos Quispe; Morten Kjeldsen; Oscar de la Torre. Numerical Modelling of the Cooling System at ALBA Synchrotron Radiation Facility to Understand its Performance. Volume 1A: Codes and Standards 2017, 1 .

AMA Style

Xavier Escaler, Montserrat Prieto, Marcos Quispe, Morten Kjeldsen, Oscar de la Torre. Numerical Modelling of the Cooling System at ALBA Synchrotron Radiation Facility to Understand its Performance. Volume 1A: Codes and Standards. 2017; ():1.

Chicago/Turabian Style

Xavier Escaler; Montserrat Prieto; Marcos Quispe; Morten Kjeldsen; Oscar de la Torre. 2017. "Numerical Modelling of the Cooling System at ALBA Synchrotron Radiation Facility to Understand its Performance." Volume 1A: Codes and Standards , no. : 1.

Conference paper
Published: 16 July 2017 in Volume 1A: Codes and Standards
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The presence of air in piping systems is a major concern in the industry. Problems like flow disruption, reduction of hydraulic machinery efficiencies or a significant drop in pipe capacity are many times related to this fact. The present paper aims to find a simple and non-intrusive experimental method to detect air in piping systems. The method, based on the dynamic properties of fluid-structure systems and underpinned by a novel low computational cost numerical simulation, accurately predicts the volume of water present in a pipe. Good agreement between numerical and experimental solutions has been obtained using much less computational effort than traditional fully coupled Fluid Structure Interaction with CFD analysis. From the numerical and experimental data, two different mathematical expressions relating the system natural frequencies, both vertically and horizontally, and the area occupied by the water have been obtained. These expressions account for the pipe geometry which theoretically would make them suitable for other diameter and wall thickness values. The paper is combined with a preliminary study of the system’s mode shapes for the different volumes of water.

ACS Style

Oscar de la Torre; Xavier Escaler; Jamie Goggins. Experimental Study of the Dynamic Response of Partially Filled Pipes Focused on Natural Frequencies and Mode Shapes. Volume 1A: Codes and Standards 2017, 1 .

AMA Style

Oscar de la Torre, Xavier Escaler, Jamie Goggins. Experimental Study of the Dynamic Response of Partially Filled Pipes Focused on Natural Frequencies and Mode Shapes. Volume 1A: Codes and Standards. 2017; ():1.

Chicago/Turabian Style

Oscar de la Torre; Xavier Escaler; Jamie Goggins. 2017. "Experimental Study of the Dynamic Response of Partially Filled Pipes Focused on Natural Frequencies and Mode Shapes." Volume 1A: Codes and Standards , no. : 1.

Journal article
Published: 01 February 2017 in Journal of Fluids and Structures
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ACS Style

Xavier Escaler; Oscar de la Torre; Jamie Goggins. Experimental and numerical analysis of directional added mass effects in partially liquid-filled horizontal pipes. Journal of Fluids and Structures 2017, 69, 252 -264.

AMA Style

Xavier Escaler, Oscar de la Torre, Jamie Goggins. Experimental and numerical analysis of directional added mass effects in partially liquid-filled horizontal pipes. Journal of Fluids and Structures. 2017; 69 ():252-264.

Chicago/Turabian Style

Xavier Escaler; Oscar de la Torre; Jamie Goggins. 2017. "Experimental and numerical analysis of directional added mass effects in partially liquid-filled horizontal pipes." Journal of Fluids and Structures 69, no. : 252-264.

Journal article
Published: 20 January 2017 in Journal of Fluids Engineering
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A fluid–structure interaction (FSI) system has been solved using the coupled acoustic structural finite element method (FEM) to simplify the cavitating flow conditions around a hydrofoil. The modes of vibration and the added mass effects have been numerically simulated for various flow conditions including leading edge attached partial cavitation on a two-dimensional NACA0009 hydrofoil. The hydrofoil has been first simulated surrounded by only air and by only water. Then, partial cavities with different lengths have been modeled as pure vapor fluid domains surrounded by the corresponding water and solid domains. The obtained numerical added mass coefficients and mode shapes are in good agreement with the experimental data available for the same conditions. The study confirms that the fluid added mass effect decreases with the cavitation surface ratio (CSR) and with the thickness of the cavitation sheet. Moreover, the simulations also predict slight mode shape variations due to cavitation that have also been detected in the experiments. Finally, the effects of changes in cavity location have been evaluated with the previously validated model.

ACS Style

Xin Liu; Lingjiu Zhou; Xavier Escaler; Zhengwei Wang; Yongyao Luo; Oscar De La Torre. Numerical Simulation of Added Mass Effects on a Hydrofoil in Cavitating Flow Using Acoustic Fluid–Structure Interaction. Journal of Fluids Engineering 2017, 139, 041301 .

AMA Style

Xin Liu, Lingjiu Zhou, Xavier Escaler, Zhengwei Wang, Yongyao Luo, Oscar De La Torre. Numerical Simulation of Added Mass Effects on a Hydrofoil in Cavitating Flow Using Acoustic Fluid–Structure Interaction. Journal of Fluids Engineering. 2017; 139 (4):041301.

Chicago/Turabian Style

Xin Liu; Lingjiu Zhou; Xavier Escaler; Zhengwei Wang; Yongyao Luo; Oscar De La Torre. 2017. "Numerical Simulation of Added Mass Effects on a Hydrofoil in Cavitating Flow Using Acoustic Fluid–Structure Interaction." Journal of Fluids Engineering 139, no. 4: 041301.

Research article
Published: 09 August 2016 in Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
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The first three mode shapes of a cantilevered NACA0009 hydrofoil were experimentally investigated in air and under different flow conditions in a cavitation tunnel. First and second bending modes and first torsion mode were determined in resonance conditions with the hydrofoil vibrating in air, in still water, in flowing water, or with leading edge sheet cavitation. The hydrofoil was excited with embedded piezoelectric ceramic patches, and the response was measured along the surface at selected positions by means of a laser Doppler vibrometer. The modes of vibration obtained from a cross correlation analysis of the signals were compared for the different conditions, and the most significant differences were identified. In particular, it was found that the mode shape deformation and the location of the nodal lines are dependent on the fluid conditions.

ACS Style

O De La Torre; X Escaler; Eduard Egusquiza; Mohamed Farhat. Experimental mode shape determination of a cantilevered hydrofoil under different flow conditions. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 2016, 230, 3408 -3419.

AMA Style

O De La Torre, X Escaler, Eduard Egusquiza, Mohamed Farhat. Experimental mode shape determination of a cantilevered hydrofoil under different flow conditions. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. 2016; 230 (19):3408-3419.

Chicago/Turabian Style

O De La Torre; X Escaler; Eduard Egusquiza; Mohamed Farhat. 2016. "Experimental mode shape determination of a cantilevered hydrofoil under different flow conditions." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 19: 3408-3419.

Review
Published: 03 December 2015 in Journal of Physics: Conference Series
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Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed.

ACS Style

X Escaler; Oscar De La Torre; Mohamed Farhat. Review of parameters influencing the structural response of a submerged body under cavitation conditions. Journal of Physics: Conference Series 2015, 656, 012150 .

AMA Style

X Escaler, Oscar De La Torre, Mohamed Farhat. Review of parameters influencing the structural response of a submerged body under cavitation conditions. Journal of Physics: Conference Series. 2015; 656 (1):012150.

Chicago/Turabian Style

X Escaler; Oscar De La Torre; Mohamed Farhat. 2015. "Review of parameters influencing the structural response of a submerged body under cavitation conditions." Journal of Physics: Conference Series 656, no. 1: 012150.

Conference paper
Published: 03 December 2015 in Journal of Physics: Conference Series
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The added mass effects on a NACA0009 hydrofoil under cavitation conditions determined in a cavitation tunnel have been numerically simulated using finite element method (FEM). Based on the validated model, the effects of averaged properties of the cavity considered as a two-phase mixture have been evaluated. The results indicate that the void ratio of the cavity plays an increasing role on the frequency reduction ratio and on the mode shape as the mode number increases. Moreover, the sound speed shows a more important role than the average cavity density.

ACS Style

Xin Liu; Zhengwei Wang; Xavier Escaler; Lingjiu Zhou. Numerical evaluation of cavitation void ratio significance on hydrofoil dynamic response. Journal of Physics: Conference Series 2015, 656, 012159 .

AMA Style

Xin Liu, Zhengwei Wang, Xavier Escaler, Lingjiu Zhou. Numerical evaluation of cavitation void ratio significance on hydrofoil dynamic response. Journal of Physics: Conference Series. 2015; 656 (1):012159.

Chicago/Turabian Style

Xin Liu; Zhengwei Wang; Xavier Escaler; Lingjiu Zhou. 2015. "Numerical evaluation of cavitation void ratio significance on hydrofoil dynamic response." Journal of Physics: Conference Series 656, no. 1: 012159.

Journal article
Published: 01 December 2015 in Journal of Hydrodynamics
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The present paper focuses on the erosive cavitation behavior around a plane convex hydrofoil. The Zwart-Gerber-Belamri cavitation model is implemented in a library form to be used with the OpenFOAM. The implicit large eddy simulation (ILES) is applied to analyze the three dimensional unsteady cavitating flow around a plane convex hydrofoil. The numerical results in the cases under the hydrodynamic-conditions, which were experimentally tested at the high speed cavitation tunnel of the École Polytechnique Fédérale de Lausanne (EPFL), clearly show the sheet cavitation development, the shedding and the collapse of vapor clouds. It is noted that the cavitation evolutions including the maximum vapor length, the detachment and the oscillation frequency, are captured fairly well. Furthermore, the pressure pulses due to the cavitation development as well as the complex vortex structures are reasonably well predicted. Consequently, it may be concluded that the present numerical method can be used to investigate the unsteady cavitation around hydrofoils with a satisfactory accuracy.

ACS Style

Victor Hidalgo; Xian-Wu Luo; Xavier Escaler; Bin Ji; Alvaro Aguinaga. Implicit large eddy simulation of unsteady cloud cavitation around a plane-convex hydrofoil. Journal of Hydrodynamics 2015, 27, 815 -823.

AMA Style

Victor Hidalgo, Xian-Wu Luo, Xavier Escaler, Bin Ji, Alvaro Aguinaga. Implicit large eddy simulation of unsteady cloud cavitation around a plane-convex hydrofoil. Journal of Hydrodynamics. 2015; 27 (6):815-823.

Chicago/Turabian Style

Victor Hidalgo; Xian-Wu Luo; Xavier Escaler; Bin Ji; Alvaro Aguinaga. 2015. "Implicit large eddy simulation of unsteady cloud cavitation around a plane-convex hydrofoil." Journal of Hydrodynamics 27, no. 6: 815-823.