Дисертації з теми "Interaction fluide-structure – Ballottement (hydrodynamique)"
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Aquelet, Nicolas. "Modélisation de l'impact hydrodynamique par un couplage fluide-structure." Lille 1, 2004. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2004/50376-2004-Aquelet.pdf.
Повний текст джерелаOmrani, Abderrazak. "Calcul de modes de ballottement de liquides et de modes hydroélastiques de réservoirs par une méthode d'éléments finis de frontière : application à l'industrie aérospatiale." Compiègne, 1992. http://www.theses.fr/1992COMPD503.
Повний текст джерелаAkkaoui, Quentin. "Computational dynamics of geometrically nonlinear structures coupled with acoustic fluids in presence of sloshing and capillarity : uncertainty quantification." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2001.
Повний текст джерелаIn this thesis, we are interested in computationally modeling and simulating coupled fluid-structure systems constituted of an elastic structure partially filled with a fluid with a free surface, considering the effects of sloshing and capillarity. The internal fluid is linear, acoustic, dissipative, and the linear elastic structure is submitted to large displacements inducing geometrical nonlinearities. The work presented in this manuscript first details the theoretical study regarding such coupled fluid-structure systems and focuses on the construction and implementation of the computational model using an adapted nonlinear reduced-order model. This reduced-order model allows for performing the nonlinear dynamical simulations and for better understanding the phenomena related to each subset of the coupled system. Several numerical applications are then presented to analyze various phenomena related to the different coupling mechanisms and energy transfers in such fluid-structure system. The first development axis consists in quantifying and reducing the computational resources required for the construction of the projection basis of the reduced-order model when dealing with very-large dimension fluid-structure computational models. A new methodology is presented, which allows for reducing the computational costs required for solving three generalized eigenvalue problems that cannot be solved on medium-power computers. A second development axis is devoted to the quantification of the influence of the coupling operator between the structure and the free surface of the internal liquid allowing for taking into account the capillary contact angle condition on the triple line while considering a deformable structure. The third axis is based on experimental research published in 1962 in the framework of NASA researches for orbital launchers, which highlighted an unexpected phenomenon of large amplitude and low-frequency sloshing of an internal liquid for a medium-frequency excitation of the tank. We propose to revisit these experimental results and to explain the causes of such unexpected phenomenon through a numerical simulation taking into account the geometrical nonlinearities of the structure. Finally, the last development axis is devoted to the propagation of nonparametric uncertainties of the structure in the system by the different coupling mechanisms. The nonparametric stochastic model is the nonparametric probabilistic approach using the random matrix theory. A methodology for identifying the hyperparameter is presented, based on an experimental data set and on an inverse statistical problem. A numerical validation of this method on a simulated experimental data set is presented
Ozdemir, Zuhal. "Interaction fluide structure et analyse sismique pour les déformations non linéaires de réservoirs." Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10003/document.
Повний текст джерелаIn this thesis, fluid-structure interaction algorithms based on the Lagrangian formulation for the structure and the Arbitrary Lagragian Eulerian formulation for the fluid have been used. These algorithms can take into account the effects of geometric and material nonlinearities of the tank and nonlinear sloshing behavior of contained liquid is utilized to evaluate the actual behavior of steel cylindrical ground supported liquid storage tanks when subjected to realistic base motions. Since seismic design codes generally define ground shaking in the form of an acceleration response spectrum, earthquake ground motions is selected and processed using spectrum matching techniques in time domain to be compatible with the Turkish Seismic Design Code (2007) spectra. In addition to two horizontal components of ground motion, the vertical component is also taken into account in order to determine relative importance of vertical ground motion on the behaviors of anchored and unanchored tanks. In order to clarify the key question of tank problems whether anchoring would prevent earthquake damage to the tank, numerical analyses are carried out on the same tank model having two different support conditions: anchored and unanchored. The consistency of the provisions presented in current tank seismic design codes and finite element method analysis results are evaluated and recommendations on seismic tank design codes are presented
Malleron, Nicolas. "Contribution à l'étude des interactions fluide-structure pour l'analyse de l'impact hydrodynamique d'un système de flottabilité d'hélicoptère." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2009. http://tel.archives-ouvertes.fr/tel-00457018.
Повний текст джерелаBrandely, Anaïs. "Étude du ballottement de fluide dans les réservoirs à carburant : approches numérique et expérimentale." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2274/document.
Повний текст джерелаThe present thesis focuses on an investigation of the sloshing phenomenon in a partially filled fuel tank submitted to a harmonic excitation motion. In the first part, the confrontation of numerical results between a linear approach - taking into account viscosity - and a nonlinear approach based on a commercial code leads to define a parameter of linearity. This parameter allows determining cases of sloshing who require non-linear resolution and those who need a linear theory to predict the phenomenon. An experimental study of fluid sloshing in a rectangular tank submitted to an automotive braking is conducted. Tests leaded allow measuring global forces engendered by the motion of the fluid, pressure of fluid impact and velocity field by PIV. This chapter provides an important data base and helps to investigate on the physical phenomenon. This study is completed by CFD results. To conclude, a numerical model for fluid-structure interactions is presented. Limits of this segregated partitioned coupling in case of sloshing in tank flexibly attached are highlighted, depending mostly on the mass ratio between fluid and tank structure. An added-mass term is integrated to the corrected staggered scheme ensuring systematically the convergence of the coupled solution and reducing significantly the iterations required
Fillon, Blandine. "Développement d'un outil statistique pour évaluer les charges maximales subies par l'isolation d'une cuve de méthanier au cours de sa période d'exploitation." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2337/document.
Повний текст джерелаThis thesis focuses on statistical tools for the assessment of maxima sloshing loads in LNG tanks. According to ship features, tank cargo and sailing conditions, a sloshing phenomenon is observed inside LNG tanks. The determination of sloshing loads supported by the tank structure is derived from impact pressure measurements performed on a test rig. Pressure maxima per impact, extracted from test measurements, are investigated. Test duration is equivalent to 5 hours in full scale. This duration is not sufficient to determine pressure maxima associated with high return periods (40 years). It is necessary to use a probabilistic model in order to extrapolate pressure maxima. Usually, a Weibull model is used. As we focus on extreme values from samples, fittings are also performed with the generalized extreme value distribution and the generalized Pareto distribution using block maximum method and peaks over threshold method.The originality of this work is based on the use of an alternate measurement system which is more relevant than usual measurement system to get pressure maxima and a 480 hours measured data available for same test conditions. This provides a reference distribution for pressure maxima which is used to assess the relevance of the selected probabilistic models. Particular attention is paid to the assessment of fittings quality using statistical tests and to the quantification of uncertainties on estimated values.The provided methodology has been implemented in a software called Stat_R which makes the manipulation and the treatment of results easier
Donguy, Bundi. "Etude de l'interaction fluide structure lors de l'impact hydrodynamique." Nantes, 2002. http://www.theses.fr/2002NANT2019.
Повний текст джерелаThe purpose of this study is to develop and validate a numerical tool to simulate the three-dimensional problem of a rigid or deformable blunt body penetrating a free surface. The hydrodynamic impact problem is considered in connection with its application to model locally ship slamming. .
Podeur, Vincent. "Modélisation expérimentale et numérique du power take-off d’un bassin houlomoteur." Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0005.
Повний текст джерелаThe present work aims at studying the power take-off of a wave energy converter (WEC). This system is composed of a set of connected tanks. Rubber flaps are installed at tanks inlet and outlet to ensure a one-way flow direction. Thanks to wave induced motions of the supporting platform, sloshing appears inside the WEC tanks which feed a cylindrical basin with a centered drain hole at its bottom. Then, a bathtub vortex flow appears within this tank, where a vertical axis turbine is installed to harvest kinetic energy from the flow. The first phase of this research focuses on studying the steady bathtub flow. To do so, a dedicated experiment is built. Velocity field within the cylindrical basin, with and without the turbine, is studied via Particle Image Velocimetry (PIV). In addition, power production from the turbine and water level inside the tank are measured. These results are used to define starting hypothesis for developing a numerical model of the turbine. The second phase of this research focuses on studying the unsteady bathtub flow. For this purpose, a second experiment is built. This setup provides a more realistic environment, closer to what can be observed with the WEC system. PIV measurements are also used extensively to study the flow with and without the turbine. The last stage of this research focuses on the numerical modelling of the vertical axis turbine. The model is based on the potential flow theory. First, a two-dimensional approach is used to validate the early pieces of the model. Secondly, a three-dimensional approach is adopted to account for more complex flow features. Finally, numerical and experiment results are compared
Paré-Lambert, Olivier. "Étude de l'extraction d'énergie du phénomène de Vibrations Induites par Vortex (VIV) lorsque deux cylindres sont placés de façon cruciforme." Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/67578.
Повний текст джерелаPernod, Laëtitia. "Simulations couplées fluide-structure et étude expérimentale d’un hydrofoil composite sous écoulement hydrodynamique." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0008/document.
Повний текст джерелаThis Ph.D is sponsored by the French company Naval Group in collaboration with LHEEA Laboratory from Ecole Centrale de Nantes and GeM Institute from ICAM de Nantes, and deals with the development of new composite marine propellers with improved efficiency, improved acoustic discretion and more environment-friendly. One of the key solutions lies in the application of composite materials to marine structures, in order to benefit from their reduced weight, increased flexibility and bend-twist coupling capacity. Indeed, the latter enables the shape-adaptability of the structure to passively adapt to the incoming flow. To meet this challenge, we first set-up a tightly coupled numerical fluid-structure method using two commercial CFD (Starccm+) and CSD (Abaqus) solvers on two flexible hydrofoils and we validated this method against experimental results available in the literature. Second, we specifically developed a composite hydrofoil to behave closely like a marine propeller and tested it in the hydrodynamic tunnel of the Ecole Navale. Thanks to the combined experimental and numerical analysis of this composite hydrofoil we reached the following conclusions: i) we helped demonstrate the industrial application of a state-of-the-art strain measurement technique using optical fibers directly embedded within the composite plies, ii) we provided some insights into the physics of the fluid-structure interaction occurring on composite hydrofoils and iii) we presented the current limitations of this coupled numerical fluid-structure method relatively to its industrial application
Boëdec, Gwenn. "Modélisation d'une vésicule sous forçage hydrodynamique." Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX30025.
Повний текст джерелаVesicles are drops of radius of a few tens micrometers, bounded by an impermeable lipidmembrane of approximately 4 nm thickness, and embedded in an external viscous fluid. Thevesicle membrane is an original system from the mechanical point of view : it presents bothincompressible fluid properties (the lipids can flow freely along the membrane, but membraneis incompressible locally) and solid properties (the membrane resists to bending). The specificproperties of the membrane make the system very deformable and very constrained at the sametime.This manuscript deals with the modelisation of a vesicle subjected to external stresses of hydrodynamical origin, in the Stokes regime. A particular attention is paid to the situation of asettling vesicle. This situation is studied analytically in the small deformation regime. It is foundthat several families of non-trivial stationnary shapes exist, owing to the specific properties ofthe membrane. The study of a settling vesicle is pursued by the development of a numerical codeable to deal with large deformations. Original numerical methods are developped to deal with thecomputation of the bending and with the surface incompressibility constraint. This code permitsto study the formation of tether at the rear of a settling vesicle. These tethers are thin (typicalaspect ratio : length/radius ∼ 100) cylinders of membrane connected to the original vesicle. Itis shown that these tethered shapes are stationary shapes. A theoretical model is proposed andcompared to numerical simulations. This model shows the particular importance of tension inthese shapes. A mechanical modelling based on a curved Cosserat surface is also presented, andpermits to identify the bending contribution to the stress tensor. This contribution is a salientingredient to understand tethered shapes
Haboussa, Grégory. "Contribution à la validation des méthodes numériques pour les problèmes dynamiques couplés fluide-structure." Valenciennes, 2008. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/66881e67-4270-45a8-943c-a32adee5eda6.
Повний текст джерелаNumerous numerical methods exist that can be used to solve fluid/structure interactions during hydrodynamic impacts on deformable structures. The purpose of the present work is to define a methodology which allows validating these numerical methods. The first stage of this work is to establish experimental reference, using a pressure transducer, in order to validate these methods. A methodology of exploitation of dynamics test responses, dedicated to the elimination of such measurement if needed, in order to get the true contact pressure that deformable structures have to support during hydrodynamic impacts, is proposed. For that purpose, the dynamic calibration of a pressure transducer is performed using shock tube, and a dynamic correction function is established, first theoretically, then practically. The obtained function is then applied on existing test results coming from water drop impacts onto the studied pressure transducer, in order to calculate the corresponding contact pressure on a flat panel. The second stage of this research is to model this phenomenon with different numerical methods: Finite Element Method, Arbitrary-Lagrange-Euler (ALE) Method and Smooth Particles Hydrodynamic Method, with a conforming –or not- interface. Comparison between corrected pressure and calculated pressure, corresponding to contact pressure on a flat panel, shows that ALE Method using a conforming interface (continuous mesh) is able to give good assumption of the hydrodynamic impact phenomenon, under the hypothesis that dynamic effect are more important than numerical diffusion. In conclusion, it is possible today to simulate correctly, with ALE method, hydrodynamic impacts on deformable structures
Constantinescu, Adrian. "Modélisation 2D de l’impact d’une structure sur l’eau : initiation de l’endommagement." Brest, 2006. http://www.theses.fr/2006BRES2037.
Повний текст джерелаThe research work in this thesis covers the modeling of the impact of a 2D body with water and the subsequent appearance of macroscopic fractures. The main application is the modeling of the slamming forces acting on the ship structure in severe sea conditions. The time-dependent stresses and strains on a ship hull can provoke a premature mechanical failure due to fatigue. The main work consists in the development and validation of a numerical tool (lmpact++ ABAQUS) simulating the fluid-structure interaction during the violent impact of a body of a simple geometry (wedge, cone, cylinder, sphere, axisymmetric parabolic body, ellipsoid, etc) on a free water surface. This approach considers the effect of the deformation of the structure on the flow and vive versa. The numerical tool is based on the commercial finite element code ASAQUS and permits to calculate thee stresses and deformations, energies and the global forces for a 2D solid structure inipacting a fluid. In view of the long-term goal of aiding structural design of ships, the second objective was to bring a quantitative and qualitative representation of the beginning of the damage of a metallic structure impacting water, namely to predict the time and location of fracture initiation due to repeated slamming impacts. These phenomena are modeled here by a bifurcation of the solution for the velocity in the mechanical equilibrium equation for the deformable body
Sigrist, Jean-François. "Modélisation et simulation numérique d'un problème couplé fluide/structure non linéaire : application au dimensionnement de structures nucléaires de propulsion navale." Nantes, 2004. http://www.theses.fr/2004NANT2088.
Повний текст джерелаDucoin, Antoine. "Etude expérimentale et numérique du chargement hydrodynamique des corps portants en régime transitoire avec prise en compte du couplage fluide structure." Nantes, 2008. http://www.theses.fr/2008NANT2118.
Повний текст джерелаThe study is in the context of marine structure design such as rudder or marine propeller and is in collaboration with a naval industrial. The thesis deal with the experimental and numerical study of the hydrodynamic loading of an hydrofoil in transient regime including fluid structure interaction problems. The transient motion is defined as a pitching motion from 0 to 15° with a return to 0° for which various velocities are defined (slow, medium, fast). Reynolds numbers studied are between 750 000 and 1 500 000. Experimental and numerical approaches are carried out together, leading to an accurate study of phenomenon observed and giving response on prediction accuracy into industrial codes. Experiments deal with wall pressure, displacements and cavitation measurements in hydrodynamic tunnel. On one hand, the flow computations are done with the finite volume CFX code for which hydrodynamic models are selected in accordance to the flow case observed (Euler, viscous, turbulence model, transition model). On an other hand, the finite element code ANSYS is used for structure displacement resolution. The coupling is take into account by ensures the exchange of the physical information at the fluid structure interface. The study of the spatio temporal evolution of wall pressure around a rigid hydrofoil in transient pitching motion has been carried out. The laminar to turbulent transition is identified resulting from laminar separation bubble. For a slow pitching velocities, the transition have a strong impact on hydrodynamic loading and a plateau is observed at 5°. For high pitching velocities, the transition effects are reduced which induced a higher value before stall. A strong hystereris is observed when the angle of incidence return to 0°. Periodic pressure fluctuations are identified as vortex shedding of laminar separation bubble. For high pitching velocities, the transition is delayed whereas LSB vortex shedding frequencies and LSB size are constant. The fluid structure coupling was investigated on deformable hydrofoils. A stationary study has linked hydrodynamic loading to structural twist deformations which induced local incidence variations along the span. Then displacements of a deformable hydrofoil in transient pitching motion has shown that boundary layer events like transition and stall are clearly visible on measured hydrofoil displacements. This is confirmed by non coupled computations. Moreover, investigations of cavitating flows show that there is a strong impact of cavitation on structural behaviour, by both static and transient measurements. Significant local incidence fluctuations have been highlighted which can then creates a strong coupling between hydrofoil and cavitating flow
Ould, Abdallahi Mohamed. "Contribution à la mise en place d'une méthode d'intensimétrie à quatre capteurs." Lille 1, 2001. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2001/50376-2001-117.pdf.
Повний текст джерелаPichot, Géraldine. "Modélisation et analyse numérique du couplage filet-écoulement hydrodynamique dans une poche de chalut." Rennes 1, 2007. http://www.theses.fr/2007REN1S092.
Повний текст джерелаE are interested in the numerical simulation of the catch process at the end part of a trawl. The study of previous works emphasizes the lack of a convincing flow model. The need of a physical understanding of the flow leads us to perform experimental campaigns around a rigid cod-end net model, whose results are given in the manuscript. We propose a model based on the Navier-Stokes/Brinkman equations coupled to an equation for the turbulent kinetic energy by the means of an eddy viscosity, with appropriate boundary conditions. Existence of a weak solution to our coupled problem is proved in dimension 2. Then, we present the axisymmetric code we developed, called SeaNet. We set the parameters of the model and validate the code by comparison with the experimental results
Leroyer, Alban. "Étude du couplage écoulement/mouvement pour des corps solides ou à déformation imposée par résolution des équations de Navier-Stokes : contribution à la modélisation numérique de la cavitation." Nantes, 2004. http://www.theses.fr/2004NANT2106.
Повний текст джерелаGobert, Marie-Laure. "Etude de l'interaction entre un écoulement de couche limite instable et une structure déformable." Nantes, 2009. http://www.theses.fr/2009NANT2037.
Повний текст джерелаThis work, supported by Thales Underwater Systems through a Cifre thesis grant, and by DCNS, aims at improving the prediction of the hydrodynamic self-noise of a sonar antenna, due to the pressure fluctuations in the boundary-layer flow that develops along the dome. Noise estimations are generally based on semi-empirical models, that take only partially into account the dome flexibility. The present study readdresses the issue of the hydrodynamic noise, in the simplified archetype case of an unstable boundary layer flow along an elastic flat plate. The first part of the study consists in the direct numerical simulation of a two-dimensional boundary layer flow, characterized by a highly supercritical Reynolds number, over an elastic clamped plate. The incompressible Navier-Stokes equations are solved by means of a time-dependent mapping, associated to a mixed finite differences – Chebyshev collocation spatial discretization. A fractional step method enables a full coupling between the plate model and the fluid system. A velocity forcing is introduced in the latter, at unstable frequencies and high amplitudes, in order to give rise to convective and non-linearly saturated instabilities, which interact with the plate motions. The latter vibrates around an initial bent state resulting from the coupling with the non perturbed flow. Plates of various materials and lengths are tested, to characterize the vibrations, in terms of levels and spatial structures, as well as their retro-action on the flow instabilities, depending on the values of the plate natural frequencies. For the cases considered in the present investigation, we observe that the wall pressure spectrum possesses additional modal components, with very low wavenumbers and relatively high frequencies, which may give rise to increased radiation. A post-treatment is implemented to estimate the noise generated by the boundary layer velocity fluctuations. The radiated pressure in the uniform flow domain is evaluated from the simulation data in the framework of the Lighthill's analogy. The calculations are performed in the spectral domain, using an appropriate Green function whose expression takes into account the presence of the elastic plate. In this approach, the plate vibrations induce at some frequencies, including the plate natural frequencies, higher radiated pressure levels than in the rigid case, by favouring larger spatial structures. Additional models, derived from the same formulation, but taking into account the boundary layer compressibility in the computation of the vibratory contributions, highlight a clear increase in the radiated pressure levels in a wide frequency range around the plate natural frequencies, when the latter are distinct from the forcing frequencies, as well as the benefit from considering a full coupling in comparison to classical approaches based on a weak coupling assumption. Finally, the fluid-structure system is investigated experimentally using a hydrodynamic tunnel setup, in order to measure the vibrations of an elastic clamped plate triggered by a transitional or turbulent boundary layer flow, as well as the radiated noise in the cavity beneath the plate, which is equipped with a hydrophone. The measurements, acquired using laser vibrometry and laser Doppler velocimetry, are detailed and analysed
Dalmon, Alexis. "Simulation numérique du ballottement d'ergol et modélisation de l'interaction fluides-membrane dans un réservoir de satellite." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30256/document.
Повний текст джерелаPropellant sloshing in tanks is one of the most important disturbances of satellite stability in orbit. Considering low-inertial manoeuvres, there is no analytical model and experimental facilities require long time period of microgravity conditions. Thus, this PhD thesis aims to predict this phenomenon by numerical simulations. The study is based on the DIVA code which solves the Navier-Stokes equations for two-phase flows with the level-set method and the Ghost Fluid method. Two tank technologies are studied: simple tanks, which only contain the liquid propellant and the gas maintaining the pressure, and diaphragm tanks, for which a hyperelastic membrane separates both fluids. In the first case, a parametric study on the sloshing effects is done considering rotational manoeuvres and the different behaviours observed are described in relation to the study parameters. Thereafter, the data from the FLUIDICS experiment, sent to the International Space Station, are compared to the numerical results and exhibit good agreement. In the second case, a fluids-membrane interaction model inspired from works on the deformation of biological cells is developed. The membrane strains and stresses are computed in an Eulerian way, from which the force exerted by the membrane on the surrounding fluids is deduced and integrated in the two-phase flows solver. The numerical results are validated by comparison with benchmarks from the literature
Messahel, Ramzi. "ALE and SPH formulations for Fluid Structure Interaction : shock waves impact." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10022/document.
Повний текст джерелаThis thesis focuses on the numerical study of the propagation of shock waves in compressible multiphase flows and fluid structure interaction. Two approaches are being studied for the numerical solution of the fluid part: the ALE approach (Arbitrary Lagrangian Eulerian) and the Lagrangian SPH (Smoothed Particle Hydrodynamics) approach; while the structure part is solved by a conventional FE (Finite Element). The numerical investigation of the ALE and SPH methods are the two main areas of research.Water Hammers phenomena occuring in nuclear industries are investigated in this thesis. During a Water Hammer, the shock waves reflections in nuclear piping may drop locally the water pressure below its saturation pressure and generate cavitation. The three equations HEM (Homogeneous Equilibrium Model) phase change model proposed by Saurel et al. (1999) is studied and applied to solve water hammers. The obtained results are compared with experimental data. Despite the use of renormalization techniques in SPH, instabilities (numerical oscillations) are developed at the interface between particles from different materials. These instabilities restrict the use of traditional SPH schemes to problems with low density ratio. In order to solve the shock problems in the compressible regime, the scheme originally proposed by Hu and Adams (2006) is adapted to fully compressible regime (FC-SPH) by considering the coupling between the density and the smoothing length. The different SPH schemes are compared for 1-D and 2-D multiphase shock problems. Validation is performed in comparison with exact solutions for 1-D problems and ALE solution for 2-D problems
Nunez, Ramirez Jorge. "A multi time-step partitioned approach for the coupling of SPH and FE methods for nonlinear FSI problems." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI040/document.
Повний текст джерелаA method to couple smoothed particle hydrodynamics and finite elements methods for nonlinear transient fluid–structure interaction simulations by adopting different time-steps depending on the fluid or solid sub-domains is proposed. These developments were motivated by the need to simulate highly non-linear and sudden phenomena that take into acount solid impacts and hence require the use of explicit time integrators on both sub-domains (explicit Newmark for the solid and Runge–Kutta 2 for the fluid). However, due to critical time-step required for the stability of the explicit time integrators in, it becomes important to be able to integrate each sub-domain with a different time-step while respecting the features that a previously developed mono time-step coupling algorithm offered. For this matter, a dual-Schur decomposition method originally proposed for structural dynamics was considered, allowing to couple time integrators of the Newmark family with different time-steps with the use of Lagrange multipliers
Melot, Vincent. "Hydrodynamique instationnaire d'un cylindre sous choc." Phd thesis, Université de Nantes, 2006. http://tel.archives-ouvertes.fr/tel-00124063.
Повний текст джерелаClement, Adrien. "Étude hydroacoustique de la réponse d'une structure à une excitation de couche limite turbulente." Thesis, Paris, ENSAM, 2015. http://www.theses.fr/2015ENAM0033/document.
Повний текст джерелаThe following work consist in the study of the vibroacoustic response of a structure submerged in fluid, under a turbulent boundary layer flow, the response of the structure is driven by the low wavenumber behaviour, for a small Mach number. This work aims at providing better means of predicting the noise radiated in such setups, mainly regarding stealthiness of ships and submarines and noise radiated by outer structures.A numerical modal analysis based on the (u,p,φ) formulation available in the finite element software Code_Aster is performed. The pressure induced by the boudary layer is then described as a sum of plane waves and several harmonical analysis are performed on the reduced problem, projected on the (u,p,φ) modal basis, one for each term of the sum. This allows us to account for the fluid-structure interaction (inertial and acoustic) in confined and infinite fluid domains. Most numerical models found in scientific papers are making the assumption of a light fluid, or a fluid loaded plate, thus not taking clearly into account the fluid-strucure interaction or only the inertialpart. Here the interaction due to the acoustic field radiated by the plate is fully accounted for.The validity of the proposed numerical method is assesed and numerical results are compared to data obtained from an experimental setup used within a hydrodynamic tunnel. Numerically, a good reproduction of the behaviour of the plate is obtained, both in terms of displacement and spectral levels. The acoustic levels are also compared to their numerical counterparts at the position of the transducer. Moreover, an experimantal analysis is performed, for backward and forward steps of height smaller than the thickness of the boundary layer, in order to investigate the influence of such configurations on the boundary layer excitation and on the vibroacoustic response
Cerqueira, Stéphane. "Étude du couplage aéro-mécanique au sein des moteurs à propergol solide." Thesis, Paris, ENMP, 2012. http://www.theses.fr/2012ENMP0011/document.
Повний текст джерелаFluid Structure Interaction of an inhibitor with the internal flow induced by wall injection was studied in an axisymmetric cold flow apparatus. Experiments were carried out over a wide range of injection velocities in order to underline how the obstacle not only modifies the mean flowfield but also its entire dynamic behaviour.The resulting instability (from the interaction of the unstable shear layer with the Taylor-Culick flow) exhibits a significant shift with respect to the Taylor-Culick instability and therefore emphasizes the strong impact of the inhibitor on hydrodynamics.The mecanisms responsible of such behaviour are studied in this thesis with the help of global linear stability analysis and multi-physics numerical computations
Levenez, Hauchecorne Marc. "Contribution à l'étude de l'interaction non linéaire entre le milieu marin et une structure cylindrique rigide." Le Havre, 2003. http://www.theses.fr/2003LEHA0010.
Повний текст джерелаThis experimental job treats about the effects of an oscillating plane or elliptic flow on a rigid circular cylinder. The studied oscillating flows are generated auround the cylinder by periodical movements of the cylinder in a still water tank. The first part of this study concerns regulating and the qualification of experimental device which gives the acquisition of strengthes and the video recording of wakes done by oscillating flow. The flow visialization is carried out by floating particules ; it allows to observe the influence of reduced amplitude AX/D on the length of drag zone LR during the starting phase of flow. The strength measurements made, show a good correlation with the different flow patterns which are classified in the (?,KC) plane on the following ranges : 700
Mohamad-Alderf, Nisrine. "Prédiction numérique des aspects instationnaires du surenfoncement dynamique d'un navire dans des chenaux fortement confinés." Compiègne, 2010. http://www.theses.fr/2010COMP1854.
Повний текст джерелаWe present a numerical model for dynamic phenomenon of squat by finite elements analysis. Lt proposes a set of modular and numerical tools therefore interchangeable. This model enables the study of the interaction betwen a two-dimension potential flow, in highly restricted waterways on irregular shaped bottom with stationary free surface. The proposed model has been validated by a stability model based on the extension of the one dimensional theory of Schijf (1949) to the dynamic effects. It is shown by testing into account the dynamic contributions of squat, the condition of stability given by the current approaches is not valid anymore
Rebufa, Jocelyn. "Vibrations de ligne d'arbre sur paliers hydrodynamiques : influence de l'état de surface." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC044/document.
Повний текст джерелаThe hydrodynamic bearing provides good damping properties in rotating machineries. However, the performances of rotor-bearings systems are highly impacted by nonlinear effects that are difficult to analyze. The rotordynamics prediction requires advanced models for the flow in the bearings. The surface of the bearings seems to have a strong impact on the lubricant flow, acting on the static and dynamic properties of the rotating parts. This study aims to enhance the simulation of the bearings’ surface state effect on the motion of the rotating shaft. The flexible shaft interacts with textured hydrodynamic bearings. Multi-scales homogenization is used in a multi-physics algorithm in order to describe the fluid-structure interaction. Different models are used to account for the cavitation phenomenon in the bearings. Nonlinear harmonic methods allow efficient parametric studies of periodic solutions as well as their stability. Moreover, a test rig has been designed to compare predictions to real measurements. Several textured shaft samples modified with femto-seconds LASER surface texturing are tested. In most cases the experimental study showed similar results than the simulation. Enhancements of the vibration behaviors of the rotor-bearing system have been revealed for certain texturing patterns. The self-excited vibration, also known as "oil whirl" phenomenon, is stabilized on a wide rotating frequency range. However, the simulation tool does not predict well the enhancements that are observed. Vortices in surface texturing patterns have been revealed numerically with Navier-Stokes equation resolution. These results are opposed to the classical lubrication hypothesis. It is also a possible explanation of the enhancements that are experimentally measured with textured bearings
Träsch, Martin. "Caractérisation expérimentale et numérique du comportement hydrodynamique d’une hydrolienne à membrane ondulante." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I009/document.
Повний текст джерелаThe thesis presented in this document deals with the characterization of the behavior of an undulating membrane tidal energy converter. This kind of device uses the flutter instabilities occurring between a semi-rigid pre-strained membrane and a fluid flow in order to convert the sea currents energy. Above a certain critical flow speed, the structure undulates, thus activating the linear converters fixed on it. In order to study this system, an experimental model is developed and tested in a flume tank. The power conversion system is simulated by hydraulic dampers. The membrane’s dynamics is analyzed in many configurations through trajectory and force measurements, and leads to a parametric study. More realistic flow conditions are also studied, such as the impact of current direction influence and the influence of surface waves on the behavior of the system. Wake characterization is carried out with two-dimensional PIV measurements. Scale effects and confinement are also studied through a comparison with a bigger scale prototype tested in tank and at sea.In addition to the experimental study, an analytical model and a numerical model are developed and compared with experiments. The linear analytical model is based on Euler-Bernouilli’s beam theory and on Lighthill’s slender body theory. It is solved in the frequency domain and gives good undulation frequency and critical speed results. The numerical model uses strong interactions between a fluid code using the vortex method and a structure code based on corotationnal finite elements. This model is validated on an experimental case
Caleyron, Fabien. "Simulation numérique par la méthode SPH de fuites de fluide consécutives à la déchirure d'un réservoir sous impact." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00711040.
Повний текст джерелаHuang, Zhaoyuan. "Ship-waves modelling and their interactions with inland waterways." Electronic Thesis or Diss., Compiègne, 2022. http://www.theses.fr/2022COMP2686.
Повний текст джерелаThe subject of this thesis concerns the investigation of ship hydrodynamics, shipinduced wave modeling, and wave-bank interactions in restricted waterways by CFD approaches based on OpenFOAM. The first part of this thesis is focused on the study of the hydrodynamics of ships in a restricted environment. This consists of the characterization of the flow around the ship and the generation of waves according to the geometric and kinematic characteristics of the ship and also the geometric characteristics of the waterway channel. To this end, the steps of numerical modeling adapted to navigation in a confined environment, which concern the preference of meshgeneration, numerical schemes, etc., was developed. The second part is devoted (1) first to the validation and comparison of the numerical results with the experimental measurements from the laboratory of the CNR (Compagnie Nationale du Rhône) are carried out; (2) next to the examination of the ship’s forward resistance according to different geometric configurations of the waterway channel (width, water depth, slope, etc.) (3) finally, to the implementation of a six-degree-of-freedom model (6DoF) to assist in the modeling of the sinkage and trim processes of ships in restricted waterways. Meanwhile, the critical effects of ships under different speed conditions in restricted environments were also researched and analyzed. The third part of the thesis deals with the study of the influence of waves induced by ships on the banks of inland waterways and in particular on the stability of the bank protection blocks. The erosion effect caused by the impact and shear of ship-induced waves on the exposed river bank was studied. The armor protection layer on the river bank is composed of discrete blocks and these blocks are regarded as rigid bodies that can collide with each other and with the banks. Thus, in this part, a CFD-DEM solver, SediFoam, was applied to (1) take into account the solid-solid and solid-boundary of domain rigid contact and collision processes and (2) investigate the stability of the rocky layer of banks, based on the average of the movements of the blocks
Otsuka, Masahiko. "Applications effectives de l'onde de choc hydrodynamique générée par pulsation électrique ou par explosion." Lille 1, 2007. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2007/50376-2007-9.pdf.
Повний текст джерелаA choc wave generated by an underwater explosion or electric pulsed power can be used for industrial applications. Ln automotive and aerospace industry, sheet metal forming is usually used for parts production. Ln metal forming we usually encounter numerical difficulties as spring back problems, which requires implicit time integration, since the time for the structure to damp out from high frequency vibrations is long compare to loading time. Metal forming has a high cost for industrial applications. . Pressure loading due to the press machine in metal forming can be generated through pressure waves from detonation points in hydrodynamic medium. The aim of this work, which has an experimental part, that is validated by numerical simulation, consists of generating pressure waves for dynamic problems, through discrete detonation points, at different locations and detonating at different detonation time. Pressure waves from detonation create a structure loading similar to the one created by the press machine in metal forming. The problem is a fluid structure interaction problem, where the fluid has high damping properties compare to those of ambient air. The fluid is solved using compressible Navier-Stokes equations with equation of state relative to explosive material, the structure is solved with structural dynamic equations, using explicit time integration
Gartner, Nicolas. "Identification de paramètres hydrodynamiques par simulation avec Smoothed Particle Hydrodynamics." Electronic Thesis or Diss., Toulon, 2020. http://www.theses.fr/2020TOUL0004.
Повний текст джерелаThis thesis focuses on techniques that allows the simulation of dynamic interactions between an underwater vehicle and the surrounding water. The main objective is to propose a satisfactory solution to be able to test control algorithms and hull shapes for underwater vehicles upstream of the design process. In those cases, it would be interesting to be able to simulate solid and fluid dynamics at the same time. The idea developed in this thesis is to use the Smoothed Particles Hydrodynamics (SPH) technique, which is very recent, and which models the fluid as a set of particles without mesh. In order to validate the simulation results a first study has been performed with a hydrodynamic pendulum. This study allowed the development of an innovative method for estimating the hydrodynamic parameters (friction forces and added mass) which is more robust than previous existing methods when it is necessary to use numerical derivatives of the measured signal. Then, the use of two types of SPH solver: Weakly Compressible SPH and Incompressible SPH, is validated following the validation approach proposed in this thesis. Firstly, the behaviour of the fluid alone is studied, secondly, a hydrostatic case, and finally a dynamic case. The use of two methods for modelling the fluid-solid interaction: the pressure mirroring method and the extrapolation method is studied. The ability to reach a limit velocity due to friction forces is demonstrated. The results of the hydrodynamic parameters estimation from simulation tests are finally discussed. The simulated added mass of the solid approaches reality, but the friction forces currently seem not to correspond to reality. Possible improvements to overcome this problem are proposed
Peronne, Simon. "Modélisation expérimentale et analyse spatio-temporelle de l'hydrodynamique de la zone de déferlement à la zone de swash." Caen, 2010. http://www.theses.fr/2010CAEN2064.
Повний текст джерелаA study on the dynamics of the free surface and flow from the surf zone to the swash zone is proposed, based on results obtained from an experimental model in wave flumes, monitoring Lagrangian of the free surface and Eulerian measurements of the internal flow. After an inventory of results related to this area, a first part is devoted to the description of measuring systems, validation of measurement tools in this area and the presentation of the possible swells scenarios. Secondly, the use of algebraic and analytic tools in data processing is described and justified. A method for extracting the bore velocity from the surf zone from video measurements is also presented. The analytical work is divided into four stages. An analysis of the characteristics of the bore in the surf zone is proposed based on the video measurements. Then, the generation and eventual release of secondary waves (high or low frequencies) from non-linear processes, through different approaches classical and original, is treated. A comparison between the secondary wave generation and the dissipation of the potential energy is proposed and a study on wave pairing is also written. Thus, the internal flow in the transition zone between the inner surf zone and swash zone is studied to describe the interactions between offshore currents generated during the backwash phase and incident bore. Finally, after an analysis of boundary conditions in the inner surf zone, the last part is devoted to the study of the flow in the swash zone and the related bottom shear stress and friction factor
Randrianantenaina, Cyriaque Donat. "Contribution à l'étude expérimentale des écoulements confinés à surfaces libres : application à l'interaction fluide-structure dans un compartiment de JIG artisanal." Thesis, Le Havre, 2016. http://www.theses.fr/2016LEHA0033/document.
Повний текст джерелаThe work realized under this co-supervised thesis concerns two study areas of fluid-structure interaction. The first concerned the Mineral Engineering and deals with the interaction between a moving grate in a sluice and the confined flow associated. The second concerns the fundamental Hydrodynamics and deals with the interaction of a cylinder mounted on flexible supports and a free surface flow in presence of plane wall. Our work contributes to the study a confined free surface flow by experimental approach. We coupled techniques of CCD camera visualization, velocity fields measurements by PIV and hydrodynamic forces to qualify the dynamics of structure motion in the flow. Experimental methods and devices are applied to the study the flow around two simplified models of a moving JIG grate and then to study a vibrating cylinder due to flow. Treatments of PIV data acquisitions by multivariable statistical POD enabled us to describe evolution of recirculation zones in the compartment and unsteady velocity field. Experimental study was completed by a numerical simulation of Jig model by using ANSYS14.5 and a numerical wake oscillator model for the case of the cylinder. This work highlighted a simple technique to give motion, in a sluice, a attached net to a cylinder and to study effects of free surface flow confinement on a vibrating cylinder
Tassin, Alan. "Modélisation tridimensionnelle d'impacts hydrodynamiques pour l'étude du tossage des bulbes d'étrave." Brest, 2010. http://www.theses.fr/2010BRES2029.
Повний текст джерелаThe present work deals with the modelling of water impacts in order to determine the hydrodynamic loads occurring during bulbous bow slamming. A three-dimensional model of water impact based on the Wagner theory has been developed. Such an approach is attractive, as it is accurate for blunt bodies and requires low computational resources. A new numerical method is proposed to solve the threedimensional Wagner problem by using the displacement potential approach and the Boundary Element Method. The hydrodynamic pressure is determined with the modified Logvinovich model. The proposed approach has been used to study several three-dimensional bodies. In addition, experimental tests have been carried out by using a hydraulic shock machine and CFD investigations have been made using a Finite Element software. A very good agreement between the three approaches has been observed. Furthermore, the efficiency of the proposed approach highlights the possibility of using it as a practical tool for preliminary design or optimization
de, Moraes Franklin Erick. "Dynamique de dunes isolées dans un écoulement cisaillé." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/302/.
Повний текст джерелаThe transport of solid particles entrained by a fluid flow as bed-load is frequently found in nature and in industrial environments. If bed-load takes place over a non-erodible ground, and if the particles flow rate is small enough and the fluid flow one-directional, an initial thin continuous layer of particles becomes discontinuous and composed of isolated dunes with a crescentic shape: the barchans. We present here an experimental study concerning barchans dynamics when submitted to a rectangular closed-conduit turbulent fluid flow. On the one hand, we investigate the migration of barchan dunes. On the other hand, we investigate the fluid flow perturbation caused by the dune, in particular the shear stress acting on its surface
Miras, Thomas. "Effets de la viscosité et de la capillarité sur les vibrations linéaires d'une structure élastique contenant un liquide incompressible." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2013. http://tel.archives-ouvertes.fr/tel-00877348.
Повний текст джерелаDiallo, Djamal Moussa. "Modélisation mathématique et simulation numérique de l'hydrodynamique : cas des inondations en aval du barrage de Diama." Phd thesis, Université de Franche-Comté, 2010. http://tel.archives-ouvertes.fr/tel-00545770.
Повний текст джерелаArbie, Muhammad Rizqie. "Stability of self-propelled body wake." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4754/document.
Повний текст джерелаThe caudal fin of swimming animals can be modelled as a thrust-producing flapping foil. When considered alone, such a foil produces on average a jet wake with a positive net momentum. It has been argued that the instability characteristics of these averaged wakes are linked to the propulsion efficiency of swimming animals. Here, we reconsider this question by taking into account both the thrust and the drag exerted on a self-propelled swimming body. To do so, we study the stability of a family of momentumless wakes, constructed as the Oseen approximation of a force doublet moving at constant velocity. By performing a local stability analysis, we first show that these wakes undergo a transition from absolute to convective instability. Then, using the time-stepper approach by integrating the linearised Navier-Stokes system, we investigate the global stability and reveal the influence of a non-parallel base flow as well as the role of the locally absolutely unstable upstream region in the wake. Finally, to complete the global scenario, we address the nonlinear evolution of the wake disturbance. These results are then discussed in the context of aquatic locomotion. According to the present stability results, the momentumless wake of aquatic animals is generally stable, whereas the corresponding thrust part is unstable. It is therefore essential to consider all forces exerted on a self-propelled animal when discussing its wake stability and its propulsion efficiency
Ercolanelli, Julien. "Étude numérique et expérimentale d'un système couplé stabilisateur et récupérateur d'énergie des vagues Experimental and numerical investigation of sloshing in anti-roll tank using effective gravity angle Experimental and numerical assessment of the performance of a new type passive anti-roll stabilisation system." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0008.
Повний текст джерелаGeps Techno's development is based on an innovative concept of a floating structure intended to produce electrical energy from several renewable marine energy sources, including wave power. The wave power system developed by Geps Techno is based on circulating water and creating a vortex within it. By taking advantage of the liquid hull phenomenon, the concept can also be used as a stabilization system for a ship or any other floating platform. The short-term objective of the company is the development of this technology allowing the stabilization and recovery of wave energy and for which there remain technological obstacles to be removed in order to achieve the viability and profitability of the system. To do this, in October 2015 Geps Techno launched the IHES (Integrated Harvesting Energy System) project, which consists of building a demonstrator of its wave power platform concept. The IHES project is one of the projects of the roadmap of the "Ecological ships" plan of New Industrial France. It is supported by Bpifrance within the framework of the Investments for the Future - Industrial Projects for the Future program. In order to master the objectives of stabilization and energy recovery, Geps Techno is studying the technological aspects necessary to switch from the energy available at wave level to that available at the wave turbine turbine. The Ph.D. thesis work supported by Fourestier in May 2017 focused on a first part "Definition and control of internal flows in the wave power system". Using CFD modeling, the latter resulted in operational models characterizing internal flows. This Cifre Ph.D. thesis follows on from Fourestier's work and deals with a second part "Modeling of the coupled platform / wave power system". All of this work should lead to an operational computer code correlated with experimental results making it possible to study the internal flow and the behavior of the float subjected to swell
Robert, Marie. "Modélisation numérique du comportement hydroélastique des navires sur houle non linéaire." Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0047.
Повний текст джерелаThe increase of large ships dimensions shifts their structural natural frequencies towards common wave frequencies, inducing more interactions between the classic seakeeping response and the structural response. Accurate modeling of wavestructure interactions becomes a key issue for architects and classification societies during the design of a ship. In this respect, a new numerical tool for fluidstructure interaction is developed, combining a finite difference RANSE description of the fluid domain with ICARE-SWENSE and an analytic beam model, within a modal approach. Thanks to the use of a simple formulation for the structure part, the tool inherits ICARE-SWENSE tolerance properties with regard to large time steps, while still taking into account hydrodynamic nonlinear effects. Results presented for a flexible barge in diffraction and radiation according to flexible modes validate the first steps of the coupling procedure. Special consideration is given to hydrodynamic non linearities threshold and their impact on the structural response. A first implementation is shown for the resolution of the equation of motion for the elastic degrees of freedom. Parametric studies on ship resistance in both regular and bichromatic waves are included as a stepping stone towards future simulations of ship hydroelasticity in irregular waves
Linde, Florian. "3D modelling of ship resistance in restricted waterways and application to an inland eco-driving prototype." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2389/document.
Повний текст джерелаAn eco-driving prototype, named EcoNav, is developed with the aim of optimizing a vessel speed in order to reduce fuel consumption for a given itinerary. EcoNav is organized in several modules : - a 2D hydraulic model simulating the flow conditions (current speed and water depth) along the itinerary; - a ship resistance model calculating the thrust necessary to counteract the hydrodynamic forces ; - a fuel consumption model calculating the fuel consumption corresponding to the thrust input; - a non linear optimization algorithm calculating the optimal speed profile. In order to evaluate the fuel consumption of an inland vessel, a ship resistance numerical model is developed in the first part of this PhD. This 3D numerical model simulates the flow around an inland self-propelled vessel and evaluates the hydrodynamic forces acting on the hull. A RANS solver is coupled with a quasi-Newton approach to find the equilibrium position and calculate ship sinkage. This method is validated by comparing the results of numerical simulations to towing tank tests. The numerical results with and without sinkage are also compared to study the influence of sinkage on ship resistance and on the accuracy of the method. Additionally, some empirical models are investigated and compared with the accuracy of the numerical method. Finally, the numerical model is used to determine if channel with and water depth restriction contribute to the same amount of ship resistance increase for the same level of restriction. The results of that investigation give insight to whether channel restriction can be characterized by a unique parameter (for instance the blockage ratio) or two parameters to distinguish water depth and channel with effects. In the second part of this PhD, the numerical methods used in the speed optimization model are described and validated. The speed optimization model is then used to simulate a real case: the itinerary of the self-propelled ship Oural on river Seine, between Chatou and Poses (153 km). The optimized fuel consumption is compared with the non-optimized fuel consumption, based on AIS speed profile retrieved on this itinerary. The effects of the ship trajectory and travel duration on fuel consumption are also investigated. The results of those investigations showed that optimizing the ship speed lead to an average fuel saving of 8 % and that using an optimal track and including real time information such as lock availability and river traffic can lead to additional fuel savings
Nachtane, Mourad. "Énergies marines renouvelables et étude des performances des matériaux composites : cas d'une hydrolienne." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0010.
Повний текст джерелаRecently, Renewable Marine Energies (RME) has emerged as a tremendous opportunity for a real ecological and industrial choice to meet the growing demands for energy and also to fight global warming. The study conducted in this thesis is with in this framework of research and is focused on the investigation of one of the most promising categories of RMEs which is tidal current turbine. A new hydrofoil for the turbine was designed using BEM (Blade Element Momentum) methods and CFD (Computational Fluid Dynamics) calculations with improved hydrodynamic efficiency. Furthermore, a series of numerical studies were conducted to investigate and examine the damage behavior of composite materials under critical loadings by developing DLOAD and VUMAT routines. This numerical study assisted in understanding the problems of structural lightening, resistance to fatigue and impact loading, and other degradation phenomena of themechanical properties of a composite turbine in severe marine environments and solving the needs of the manufactures. Moreover, study about the dynamic behavior of a composite/composite bonded assembly was also conducted because joint assembly plays a vital role in reducing the mass of the structure which is of extreme relevance in the field of marine and offshore structures. Another important obstacle regarding the application of composite and bonded structures in marine was the control of hygro-mechanical coupling. Therefore in this context, additional campaign of tests was carried out on bonded composite specimens by studying the hygrothermal effect on their dynamic behavior at different deformation rates using Hopkinson bar method. This hybrid study of hygro-thermal effect of the dynamic properties of the bonded composites will aid in optimization of the structures and to move into the commercial phase with a substantial gain in LCOE (Levelized Cost of Energy) in future
Hugues, Florian. "Modelling the vibrations generated by turbulent flows in ducts." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2470/document.
Повний текст джерелаPipeline and duct vibrations can cause a range of issues from unplanned shutdownsto decreased equipment life time. Thus, the prediction of flow-induced vibrations is essential in piping design in many industrial plants, especially, for Gas industry. This study deals with the prediction of pipe flow noise and vibration at low Mach number. We aim to present a numerical and experimental study which can offer engineers a better understanding of the coupling between random excitation and duct section for two geometries (circular or rectangular). An experimental facility and measurement approach is developed and used to validate numerical predictions. Two cases are investigated: (i) a straight duct with no singularity, duct acoustic modes are excited by the Turbulent Boundary Layer (TBL) and (ii) a straight duct with a diaphragm inserted upstream generating a localized acoustic source. The acoustic contribution is either measured via cross-spectra based methods or calculated using Computational Fluid Dynamics (CFD) and aeroacoustic analogies. The response of the structure is estimated via a ‘blocked’ approach using analytical modal Frequency Response Functions (FRFs) of a simply supported finite duct. Measurements will lead to evaluate and suggest improvements to existing Cross Power Spectral Density (CPSD) empirical models in a context of internal turbulent flows. Experimental modalanalysis of a finite rectangular duct are confronted to computational methods to assess the effect of the Boundary Conditions (BCs), the resistive damping from coupling with the internal acoustic medium and aerodynamic damping. The fluid-structure coupling is analyzed through the joint acceptance function both in the spatial and wave number domain. The excitation includes both the acoustic and hydrodynamic contributions using CPSD written on the basis of Corcos, Diffuse Acoustic Field (DAF) and acoustic duct mode coherence functions. Finally, the numerical and experimental studies in this thesis were used to develop a framework for studying and modelling pipe flow noise and vibration which links CFD, analytical and empirical models to efficient random analysis techniques