Дисертації з теми "Coupage au jet"
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Tazibt, Abou-el-Foutouh. "Étude théorique et expérimentale du processus d'accélération de particules abrasives dans un jet d'eau sous très haute pression : interaction avec le matériau à découper." Lille 1, 1995. http://www.theses.fr/1995LIL10003.
Weiss, Laurent. "Contribution au développement d'un procédé de découpe laser haute-énergie / jet d'eau haute-pression couplés : Application à la découpe d'alliages métalliques." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0112/document.
For a decade, the hybrid jet cutting where a water jet acts as waveguide for the laser has been successfully used in the field of microelectronics. To develop this technology and bring it up to other markets such as automotive, boiler or aerospace, it is necessary to increase both the laser energy and the water jet pressure. At these high energy levels, new interactions that occur between light and fluid as well as the material changes caused by the hybrid jet have never been studied from a physicochemical point of view. So, at first, we have devised a system allowing measurements of optical properties of water at high pressure with a possible direct application in optical sensor for fluid pressure. In an original way, this work has allowed us to measure the refractive index and polarizability of water up to 250 MPa and model their evolution using Tait, Sellmeier and Lorentz-Lorenz equations, respectively. A direct result of this study is the creation of a model linking directly the fluid density to the measurement of its refractive index. Following these developments and after hydrodynamics simulations, we have designed a specific head for coupling a high power laser guided by high pressure water jet. Then we have tested various head types allowing the coupling of a new generation hybrid jet. In the same time, we have studied the physicochemical impact of decoupled hybrid jet where the laser and water jet are both focused, for cutting, at the surface of 301L steel and titanium alloy TA6V samples. The analysis have been done by Raman spectroscopy, X-ray diffraction (XRD), optical microscopy and scanning electron microscopy coupled with EDS (Energy Dispersive Spectroscopy) analysis and the crystallographic orientation (EBSD) analysis. During cutting, a phase transformation and an oxidized layer appear on the surface of the samples. We have shown in particular that these oxide layers and cutting residues are mainly composed of magnetite (Fe3O4) and rutile (TiO2)
Xiao, Shenglei. "The investigation on mechanical behaviours of reinforcements and machining properties during manufacturing composites with complex shapes." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I056/document.
The mechanical characteristics and deformability behaviours of reinforcements are essential knowledge to optimize manufacturing process composites with complex shapes. Meanwhile, the machining properties of composites also greatly determine the in-service performance of composite parts. This thesis is not only dedicated on the three aspects in manufacturing and machining processes to explore what characters the special features in the mechanical properties and deformability behaviours of braided fabrics, which are promising and excellent textile reinforcements for composites with complex shapes. But also to study machining processes using the abrasive water jet technique in order to further improve machining efficiency without sacrificing quality. The mechanical characteristics of braided fabrics, especially for in-plane shearing phenomenon, were originally investigated and modelled based on bias-extension test. In addition, triaxial braids were also the subject of an experimental study to determine the mechanical characteristics with regard to braiding parameters, such as braiding angle and number of yarns. The deformability behaviour of triaxial braids during the preforming step was analysed and correlated with the associated defects according to the different process conditions, such as the pressures applied. In addition, the evolution of the deformability behaviour as a function of the braiding angle was geometrically modelled and verified by experimental results. The upgraded multi-pass cutting of abrasive waterjet was firstly introduced into composites machining process based on the exploration of the corresponding material removal mechanism. It was experimentally concluded that such technique could effectively enhance the machining quality and efficiency
Avrit, Antoine. "Étude du comportement d’ablation d’une structure solide par un jet liquide chaud." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0281.
Safety studies for fast neutron reactors with sodium led to the development of mitigation systems for severe accidents. During a hypothetical severe accident, at least part of the reactor's core melts, leading to the formation of corium. The corium has to be relocated to prevent any criticality problems. Therefore, transfer tubes were integrated to the design of the core to relocate the corium from the core to a core-catcher. A jet of corium exits the transfer tubes and spreads on the core-catcher, allowing a better cooling of the corium. However, thermal ablation of the core-catcher will occur as the temperature of the corium is very high (~ 2000 - 3000 K). Thus, the core-catcher has to be dimensioned to prevent any breach due to the ablation. Experiments were performed during a previous thesis to improve understanding of the phenomenon of ablation by a free-surface jet, with a bench called HAnSoLO (Hot AblatioN of a SOlid by a Liquid - Observations). New results were obtained in the present work to address additional phenomenologies. For instance, the ablation of a solid by an immersed jet was studied. This is another situation that could occur in the real case. The effect of the roughness of the impacted solid was also addressed, and it was shown that taking roughness into account is important to design the core-catcher. All these results were used to validate a CFD code. In particular, the ablation result obtained through the numerical simulations were very similar to the experimental results for the immersed jet case. The simulations and experiments will be completed in the future to numerically treat the ablation of a metallic solid by a corium jet under reactor conditions
Assoum, Hassan. "Étude expérimentale des couplages entre la dynamique d’un jet qui heurte une plaque fendue et l’émission sonore générée." Thesis, La Rochelle, 2013. http://www.theses.fr/2013LAROS420/document.
Self-sustaining sounds related to aero-acoustic coupling occurs in impinging jets when a feedback loop is present between the jet exit and a slotted plate: the downstream-convected coherent structures and upstream-propagating pressure waves generated by the impingement of the coherent structures on the plate are phase locked at the nozzle exit. The upstream-propagating waves excite the thin shear layer near the nozzle lip and result in periodic coherent structures. The period is determined by the convection speed of the coherent structures and the distance between the nozzle and the plate. Simultaneous measurements of the velocity fields and the acoustic waves in a plane jet impinging a slotted plate were performed using time-resolved particle image velocimetry (PIV) and a microphone. A better understanding of the flow physics and the aero-acoustic coupling are obtained thanks to spatio-temporal cross-correlations between the transverse velocity and the acoustic signals. Cross-correlations are calculated using two different methods: classical analysis of the original signals and by developing a pre-whitening technique. The latter method is useful for analyzing small random signals superimposed on a high amplitude pure tone
Meslem, Amina. "Contribution à l'étude du couplage thermique entre un jet et un local climatisé." Lyon, INSA, 1997. http://www.theses.fr/1997ISAL0053.
The work we present is based both on the analysis of the jet released from an air diffusion system and the coupling of the jet with a dwelling. The first part is devoted to a bibliographical review about jets and the indices allowing to assess the thermal environment of air conditioned dwellings. The second chapter is the description of the experimental set up which has been developed in the CETIAT on Villeurbanne. The third part leads to an accurate analysis of the cold jet issued from the air diffusion system and to an identification of its main characteristics. The results display a good agreement according to more academic studies conducted on 30 and anisothermal wall jets. Finally, the last chapter sets out the study of both the performance of the air diffusion system and the thermal comfort in the occupancy zone of the dwelling
Radenac, Emmanuel. "Développement et validation d'une méthode numérique pour le couplage fluide / structure en aérothermique instationnaire." Toulouse, ENSAE, 2006. http://www.theses.fr/2006ESAE0018.
Mateu, armengol Jan. "Étude numérique des effets du couplage du rayonnement thermique aux jets turbulents libres de vapeur d'eau." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC052/document.
Radiation plays an important role in a broad range of thermal engineering applications comprising turbulent flows. The growing need for accurate and reliable numerical simulations to support the design stages of such applications is the main motivation of this thesis.Of special interest in this work are the free-shear flows and the fundamental understanding of how radiation can modify their fluid dynamics and heat trans- port as well as how their turbulence fluctuations can alter radiative transfer. The goal of this thesis is to provide high-fidelity data of turbulent free jets coupled with thermal radiation in order to develop and validate free-shear turbulent models accounting for coupling interactions. To this end, turbulent free jets are described by direct numerical simulations (DNS) coupled to a reciprocal Monte- Carlo method to solve the radiative transfer equation. The spectral dependency of the radiative properties is accounted for with an accurate Correlated-k (ck) method. The numerical study is carried out with state-of-the-art fidelity to be as representative as possible of an actual jet in a participating medium. The simulation is optimized in terms of processing time taking advantage of an acceleration method called Acoustic Speed Reduction and by injecting artificial turbulence to enhance inlet boundaries.Two direct simulations of heated jets coupled with thermal radiation are carried out. On the one hand, a heated jet with moderate radiation is simulated. The analysis of its high-fidelity coupled DNS data has allow to derive a new scaling law for the decay of the temperature profile. This scaling accounts for the effects of modified density due to moderate radiation. Moreover, it allows for distinguishing whether thermal radiation modifies the nature of heat transfer mechanisms in the jet developed region or not. On the other hand, a strongly heated free jet is computed in order to quantify the effects of radiation on mean temperature and velocity fields as well as on second order moments.Besides the coupled DNS data, a RANS solver for variable-density flows coupled with thermal radiation has been implemented during the course of this thesis. The goal is to directly quantify the accuracy of the existing turbulent models, and to identify key parameters for further modeling of coupling interactions
Berthiaux, Henri. "Modélisation du broyage fin dans un broyeur à jets d'air et à lit fluidisé : étude du couple broyeur-sélecteur." Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL154N.
Cammas, Jean-Pierre. "Circulation ageostrophique dans les systemes jet-fronts : une etude prospective du couplage dynamique haute et basse troposphere." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF21134.
Polverel, Michel. "Étude des événements à trois jets produits dans les interactions proton-antiproton au collisionneur du CERN." Paris 11, 1986. http://www.theses.fr/1986PA112372.
Hassani, Samira. "Mesure des couplages à trois bosons de jauge neutres au LHC & étude de la linéarité du calorimètre électromagnétique d'ATLAS." Paris 11, 2002. https://tel.archives-ouvertes.fr/tel-00006445.
The study of vector pair production ZZ and Zγ at the LHC allows to test the trilinear couplings. Deviations of the couplings from the SM values would indicate the presence of new physics beyond the Standard Model. Prospects for measuring neutral gauge boson couplings (NTGC) in ZZ and Zγ production with the ATLAS detector are studied in details including a fast detector simulation. NLO corrections in hadronic di-boson production are large at LHC energies, particularly in the region of maximum sensitivity to anomalous NTGC. With veto of hard jets, the qualitative shape of the 10 distributions is recovered. The expected limits on these couplings will improve the limits obtained by the LEP experiments by three to five orders of magnitude. A precise knowledge of the calorimeter energy scale is mandatory for precision measurements at the LHC. Precision studies of the linearity calorimeter response with test beam data require a good knowledge of the absolute beam energy. Two methods to estimate the field integral in the magnet were studied : a precise measurement of the magnet current and direct measurement of the field by a set of Hall probes. By taking into account the effects of hysteresis, the remnant field and the energy loss by synchrotron radiation, the beam energy is measured with good precision of 8x10^(-4). A method of weighting the longitudinal compartments of the electromagnetic calorimeter was developed. It allows to obtain a linearity response of ±0. 1% in the Monte Carlo, ±0. 3% with the test beam data. Limitations related to the calibration and the signal reconstruction are observed and must be investigated to improve the linearity studies in the data
Litaudon, Xavier. "Etude théorique et expérimentale du couplage de l'onde hybride dans Tore-Supra et jet au moyen d'antennes à multijonctions." Aix-Marseille 1, 1990. http://www.theses.fr/1990AIX11284.
Delon, Antoine. "Le chaos quantique dans la molécule de NO2 : spectroscopie en jet supersonique et modélisation des couplages vibroniques." Grenoble 1, 1991. http://www.theses.fr/1991GRE10019.
Valetoux, Hélène. "Approche expérimentale des phénomènes impliqués dans la découpe par plasma d'arc transféré : Contribution à l'étude des instabilités et du transfert thermique." Limoges, 1998. http://www.theses.fr/1998LIMO0054.
Guérassimoff, Gilles. "Etude numérique de jets d'air horizontaux et de la brumisation en vue de leur couplage pour le rafraichissement d'enceintes habitables." Paris, ENMP, 1997. http://www.theses.fr/1997ENMP0785.
Glesser, Martin. "Sons auto-entretenus produits par l'interaction d'un jet plan avec une plaque fendue : étude expérimentale et modélisation du couplage avec un résonateur." Phd thesis, Université de La Rochelle, 2006. http://tel.archives-ouvertes.fr/tel-00260176.
Gouzevitch, Maxime. "Mesure de la constante de couplage forte avec les jets hadroniques en diffusion inélastique profonde." Phd thesis, Ecole Polytechnique X, 2008. http://pastel.archives-ouvertes.fr/pastel-00004486.
Pautrizel, Jean-Baptiste. "Etude du couplage absorption-diffusion pour le rayonnement infrarouge de jets de propulseurs composites aluminisés." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2010. http://www.theses.fr/2010ECAP0036/document.
Prediction of infrared emission of exhaust plumes from aluminized composite rocket, follows mainly three steps : calculating aero-thermo-chemical values in the plume, converting those valuesto optical properties (absorption coefficient, scattering coefficient and phase function) and resolving the radiative transfer equation. This thesis is mostly devoted to this third step, and proposes new ways to use band models on two-phases and scattering media.Firstly, we extended band models to cases with thermic non equilibrium between gas and particles. Secondly, we proposed a method consisting in splitting radiance in two parts, one called un-scattered and the other scattered, from an original idea of Liu et al. The un-scattered part is solution of the radiative transfer equation obtained by ignoring scattering. As a result, the unscattered radiance can be found by using band models. By this approach, errors on spectral correlations are only present on the scattered radiance.We show the interest of thoses approches by comparing them with a line by line resolutionof the radiative transfer equation, on media representative of remote sensing cases of rocket exhaust plumes
Park, Hyun-Jong. "Etude de schemas de calcul des accidents de reactivite mettant en jeu le couplage neutronique thermohydraulique." Paris 11, 1993. http://www.theses.fr/1993PA112122.
Gouzévitch, Maxime. "Mesure de la constante de couplage forte αs avec les jets hadroniques en diffusion inelastique profonde". Palaiseau, Ecole polytechnique, 2008. http://www.theses.fr/2008EPXX0064.
Baudry, Xavier. "Couplage entre approches globales et locales cfd pour la conception d'organes hydrauliques application aux distributeurs hydrauliques et a la compensation des forces de jet." Toulouse, INSA, 1999. http://www.theses.fr/1999ISAT0045.
Thuillet, Swann. "Simulation multi-échelle de l’atomisation d’un jet liquide sous l’effet d’un écoulement gazeux transverse en présence d’une perturbation acoustique." Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0033/document.
The reduction of polluting emissions is currently a major issue in the aeronautics industry.Among the solutions developed by the engine manufacturers, lean combustion appears as an effectivetechnology to reduce the impact of combustion on the environment. However, this type oftechnology enhances the onset of combustion instabilities, resulting from a thermo-acoustic coupling.Experimental studies previously conducted at ONERA have highlighted the importanceof atomization in a multipoint injector to the combustion instabilities. The aim of this thesis isto implement the multi-scale methodology to reproduce the coupling phenomena between theatomization of the liquid jet in the presence of a crossflow (which is a simplified configuration ofan injection point of a multipoint injector) and an imposed acoustic perturbation, representativeof the effect of combustion instabilities. This type of approach can ultimately be used for the unsteadysimulation of a combustion system, and will determine the characteristic convection timesof the liquid fuel that can affect the phenomena of evaporation and combustion, and therefore theappearance of combustion instabilities. In order to validate this approach, the results obtainedfrom the simulations are systematically compared with the experimental observations obtainedwithin the framework of the SIGMA project. First, a simulation of the liquid jet in gaseous crossflowis performed. This simulation enabled us to validate the multi-scale approach : to this end,the large scales of the jet, as well as the atomization mechanisms reproduced by the simulations,are analyzed. Then, the influence of an acoustic perturbation on the atomization of the liquidjet is studied. The unsteady behavior of the jet and the spray resulting from the atomization arecompared with the experimental results using time averages and phase averages
Carlier-Cohat, Mireille. "Caractérisations théorique et expérimentale des jets supersoniques libres : modélisation du couplage entre les relaxations translationnelle et rotationnelle et mise au point d'une méthode de détermination de la masse volumique par tomographie laser." Châtenay-Malabry, Ecole centrale de Paris, 1992. http://www.theses.fr/1992ECAP0267.
SQUINABOL, FABRICE. "Mesure de la constante de couplage de l'interaction forte alphas par l'etude des jets dans l'experience h1." Paris 11, 1997. http://www.theses.fr/1997PA112065.
Favé, Claude. "Nouvelles méthodes de réduction des bruits auto-entretenus dans les jets confinés." Poitiers CEAT, 1995. http://www.theses.fr/1995POIT2343.
Ayed, Yessine. "Approches expérimentales et numériques de l’usinage assisté jet d'eau haute pression : étude des mécanismes d'usure et contribution à la modélisation multi-physiques de la coupe." Thesis, Paris, ENSAM, 2013. http://www.theses.fr/2013ENAM0056/document.
This study focuses on the machining of the Ti17 titanium alloy using high-pressure water jet assistance. Special emphasis is placed on the analysis of degradation mechanisms and tool wear during machining, with and without assistance. Wear monitoring was achieved by regular observations using both scanning electron microscope (SEM) and chemical analysis (EDS technique) to determine the areas of material deposition on the tool. These observations made it possible to explain the wear mechanisms for roughing and finishing conditions. Wear mechanisms for conventional machining and for assisted machining were found to be significantly different. Indeed, with high-pressure water jet assistance, some tool wear mechanisms are no longer activated, whereas others are accelerated. Hence, there exists an optimum water jet pressure which minimizes tool wear.To highlight the effect of water jet assistance on the thermomechanical phenomena in the chip formation zone, finite-element modeling has been performed. Fluid/structure coupling was developed to take into account the mechanical and thermal effects of the water jet. For this to be possible, the Johnson-Cook constitutive law and damage model have been identified for the Ti17 titanium alloy, under extreme conditions, over a wide range of temperatures and strain rates. This modeling has highlighted the fact that, for high-pressure assisted machining, the tool/chip contact zone is reduced. In addition, the simulation of chip fragmentation as well as the cooling effect on the tool and workpiece is possible.However, this model does not shed light on the effect of the microstructural heterogeneity of the material in the cutting zone. This is an important observation because the material studied has a very large grain size (of the order of a millimeter). For this reason, a new (multi-scale) modeling approach has been developed to take into consideration the microstructure of the material. The material is subsequently modeled as a polycrystal which obeys crystal plasticity constitutive laws. This new approach is then used to simulate chip formation, taking into account the grain orientations and phase changes that occur during the machining process
Schneebaum, Alyssa, and M. V. Lee Badgett. "Poverty in US Lesbian and Gay Couple Households." Taylor & Francis, 2019. http://dx.doi.org/10.1080/13545701.2018.1441533.
Coubez, Xavier. "Search for the standard Higgs boson produced in association with a pair of top quark in the multi-leptons channel in the CMS experiment." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE049/document.
The discovery in 2012 of the last elementary particle predicted by the Standard Model, the Higgs boson, has opened a new era in particle physics. One of the objectives now is to probe the coupling of the Higgs boson to other particles in order to confirm the validity of the model. The work of this thesis focused initially on the identification of jets coming from b quark at trigger level. The goal is to allow for the selection of one thousand events among the forty million produced every second at the LHC, by identifiying objects present in the final states of interesting physics processes such as the associated production of a Higgs boson decaying in a pair of b quark with a Z boson decaying into undetected neutrinos. The work then moved to the study of the coupling of the Higgs boson to the quark top, most massive particle in the Standard Model. After a study of one of the important background of the associated production of the Higgs boson and a top quark pair, a new method called matrix element method has been used to improve the discrimination between signal and background. This analysis has led to the first experimental evidence of coupling between the Higgs boson and the top quark
Cathelain, Marie. "Développement d’un modèle de simulation déterministe pour l’étude du couplage entre un écoulement atmosphérique et un état de mer." Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0001/document.
Modelling the dynamic coupling of ocean-atmosphere systems requires a fundamental and quantitative understanding of the mechanisms governing the windwave interactions: despite numerous studies, our current understanding remains quite incomplete and, in certain conditions, sparse field observations contradict the usual theoretical and stochastic models. Within the context of a growing exploitation of the offshore wind energy and the development of met ocean models, a fine description of this resource is a key issue. Field experiments and numerical modelling have revealed that atmospheric stability and wave effects, including the dynamic sea surface roughness, are two major factors affecting the wind field over oceans. A numerical tool has been implemented in order to study the coupling between an atmospheric flow and the seastate. A massively parallel large-eddy simulation developed by P. Sullivan at the National Center for Atmospheric Research is then coupled to a High-Order Spectral wave model developed at the Hydrodynamics,Energetics & Atmospheric Environment Laboratory in Ecole Centrale de Nantes. Numerous configurations of wind and sea states are investigated. It appears that, under strongly forced wind conditions above a small sea state, the semi-empirical laws referred to as standards in the international guidelines are a good approximation for the vertical profile of the mean wind speed. However, for light winds overlying fast-moving swell, the presence of a wave induced wind jet is observed, invalidating the use of such logarithmic laws
Chauvet, Laura. "Caractérisation expérimentale et optimisation d'une source plasma à pression atmosphérique couplée à un spectromètre de masse à temps de vol." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30302/document.
Since the beginning of the 2000's, new atmospheric pressure plasma sources have been developed. They allow the propagation of a cold plasma jet or plasma plume in open air (non-equilibrium plasma jets). Their particular properties (in terms of reactive species, low temperature and ability to extend in open air) make them useful tools in a large range of research fields such as biomedicine, decontamination and sterilization, nanomaterial synthesis and analytical chemistry. Among the plasma jet sources, some are based on a dielectric barrier discharge (DBD) configuration, which is the case of this study. This work proposes the experimental characterization of a plasma jet developed with the aim to be coupled with a Time-Of-Flight Mass Spectrometer (TOF-MS) in order to perform ambient chemical analysis. The source consists of a dielectric body surrounded by two electrodes. The source is fed by a discharge gas (helium or neon) and powered by a square alternative voltage. The main diagnostics are optical emission spectroscopy and imaging with an ICCD camera. The mass spectrometer has also been used as a diagnostic tool to identify the ions created by the jet interacting with the species present in ambient air. The jet has been studied for two gases, neon and helium, with different experimental conditions of flow rates and applied voltages. The mechanisms of the jet propagation in open air have been studied for both half periods of the voltage (positive and negative), where the passage between positive and negative streamers transited through a remnant ionized channel. The spatial and temporal distributions of the main radiative species were investigated independently for each streamer allowing the observation and identification of mechanisms responsible of the populating of the upper level of observed emissions. It was shown that the mechanisms differ according to the half period studied and also the type of gases (neon and helium) due to the difference between the energies of their metastable states. In order to lay the groundwork in ambient analytical chemistry with the plasma source, its ionization capability was evaluated. Firstly, the ions created by the jet in open air were identified and analyzed with the TOF-MS, secondly the analysis was performed with different volatile samples. The results highlighted that the jet initiated with neon as discharge gas is able to ionize as well as the jet initiated with helium. A semi quantitative study of one of the volatile samples has also been realized
Ricaud, Fabienne. "Etude de l'identification des sources acoustiques à partir du couplage de la pression en champ proche et de l'organisation instantanée de la zone de mélange de jet." Poitiers, 2003. http://www.theses.fr/2003POIT2274.
Blanc, François. "Production de son par couplage écoulement / résonateur acoustique : étude des paramètres de facture de flûtes par expérimentations et simulations numériques." Phd thesis, Paris 6, 2009. http://www.theses.fr/2009PA066616.
Blanc, François. "Production de son par couplage écoulement / résonateur accoustique : étude des paramètres de facture de flûtes par expérimentations et simulations numériques." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00476600.
Beaudet, Julien. "Caractérisations à très hautes températures de protections thermiques sous impact normal d'un jet chaud supersonique : influence du couplage aérothermique et des propriétés matériaux sur la tenue à l'ablation." Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2011. http://www.theses.fr/2011ESMA0016.
This study is focused on the characterizations of the ablative properties of different thermal protections for very high temperatures applications. Using a specific characterization method, the physical mechanisms involved during the ablation process have been identified. Two different test benches with a normal gas flow have been used in this investigation. The first one is laboratory test bench based on an oxyacetylene torch (conditions termed "thermal ablation" with a 3000°C gas temperature). The second one is a large scale facility producing a hot supersonic gas flow (Mach number = 3) and a temperature about 2000°C, leading to an "aerothermal ablation". Various composite materials have been tested by mixing different matrices, different architectures and different kind of fibers. Under thermal ablation condition (oxyacetylene torch), mass loss and surface recession are due to the thermo-oxidation reactions occurring both in the matrix and in the fibers. Once the pyrolysis reaction completed, a volatilization of the composite during the exposure is observed. In contrast, under aerothermal ablation conditions, surface recession is observed prior to the completion of the oxidation/pyrolysis reactions. Under such conditions, the degradation of local mechanical properties associated with the strong mechanical impact of the supersonic jet on the material leads to ablation. In parallel, a numerical model of ablation has been developed. One of the main requirements was to develop an engineering tool to design various types of thermal protection systems (e. G. Organic composite, ceramic composites…) and hence various ablation processes. This model is based on the oxidation/pyrolysis reactions kinetics. It has been identified for one composite material whose thermal parameters (i. E. Thermal conductivity, specific heat, density) have been fully characterized as a function of temperature and degradation state. First numerical simulations were compared to the experimental results on the oxyacetylene torch test to validate the model for a future extension of ablation modelling under aerothermal conditions
Lakmini, Hakim. "Etudes mécanistiques de réactions catalysées par des complexes de palladium mettant en jeu des réactifs organoborés : homocouplage et couplage croisé." Paris 6, 2006. http://www.theses.fr/2006PA066498.
Rodriguez, Anne. "Étude de la combustion de composés organiques grâce au couplage d'un réacteur parfaitement agité avec des méthodes analytiques spectroscopiques et spectrométriques : application à la détection des hydroperoxydes." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0246/document.
In recent years, the world is facing a major energetic issue due to the growing primary energy demand and not to mention the emissions of harmful pollutants for the environment. Researchers have been studying alternative pathways to the massive use of fossil fuels, such as the incorporation of biofuels into conventional gasoline or the development of modern technology. New types of engines using a low-temperature combustion are currently under study. They have the advantage of combining both a good performance and a reduction in pollutant emissions (like NOx and soot particles). Significant gaps of knowledge are still remaining, both on the characterization of the reactivity, the emissions and on the low-temperature gas phase oxidation chemistry of biofuels. Main objectives of this thesis are to: ? - Establish an experimental database by identifying reaction products and intermediates and more particularly during the low-temperature oxidation (from 500 to 1100K), ? - Develop and validate detailed kinetic models in order to reproduce the combustion of the fuel. Oxidation experiments were performed using a jet-stirred reactor. Thanks to its homogeneity in both temperature and concentration, it can be considered as an ideal reactor for kinetic studies. The products obtained at the outlet of the reactor have been analyzed using three complementary methods: gas chromatography (GC) and cavity ring-down spectroscopy (CRDS) and mass spectrometry (MS). The GC method is efficient in separating compounds (including isomers) and allows us to analyze a wide range of products. The CRDS method is an absorption spectroscopic technique which allows us to analyze specific species such as HCHO, H2O and H2O2. Finally MS coupled with a soft ionization technique allows us to analyze hydroperoxides products of formula R-OOH. Both H2O2 and hydroperoxides are important reaction intermediates in combustion, but there is very little experimental data available on those species. Due to their weak O-O bond, those compounds are thermolabile and difficult to analyze (undectable using GC). This thesis allowed the study of different fuels oxidation, from hydrocarbons (n-pentane, n-hexane, n-hexenes, n-heptane, iso-octane, n?decane) to oxygenated compounds (dimethyl-ether, 1-hexanol, hexanal, large methyl-esters)
Hassani, Samira. "Mesure des couplages à trois bosons de jauge neutres au LHC & Etude de la linéarite du calorimètre électromagnétique d'ATLAS." Phd thesis, Université Paris Sud - Paris XI, 2002. http://tel.archives-ouvertes.fr/tel-00006445.
Michaud-Poussel, Emmanuelle. "Etude des couplages plasmas - spectrométrie de masse en vue d'applications analytiques : mise en oeuvre et espèces observées." Lyon 1, 1989. http://www.theses.fr/1989LYO10139.
Manuel, Isabelle. "Étude cinétique et modélisation de réactions mises en jeu en calalyse trois-voies." Paris 6, 2002. http://www.theses.fr/2002PA066437.
Ayed, Yessine. "Approches expérimentales et numériques de l'usinage assisté jet d'eau haute pression : étude des mécanismes d'usure et contribution à la modélisation multi-physiques de la coupe." Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2013. http://pastel.archives-ouvertes.fr/pastel-00973532.
Bendjebbar, Fatna. "Modélisation hydrodynamique d'une torche à plasma couplée inductivement." Thesis, Clermont-Ferrand 2, 2013. http://www.theses.fr/2013CLF22340/document.
The purpose of the work was the numerical modeling of the inductive coupling plasma torch. (ICP). We have established the necessary databases: composition, thermodynamic and transport properties applied to argon mixtures of nitric acid and water. The hydrodynamic model of the ICP torch (7 coils) considers the plasma at thermodynamic equilibrium and uses the Navier-Stokes equations to describe the plasma flow and the Maxwell equations to describe the evolution of the electric field and the magnetic field
Duluard, Amandine. "Transport polarisé en spin à travers une barrière de MgO (001) : magnétorésistance et couplage magnétique." Phd thesis, Université de Lorraine, 2012. http://tel.archives-ouvertes.fr/tel-00769754.
Fontane, Jérôme. "Transition des écoulements cisaillés libres à densité variable." Phd thesis, Toulouse, INPT, 2005. http://oatao.univ-toulouse.fr/7338/1/fontane.pdf.
Chéron, Victor. "Couplage de la méthode de capture d'interface et de particules lagrangiennes pour la simulation de l'atomisation." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR097.
The study of the liquid jet’s atomization consisting of two immiscible phases is a fundamental research subject. The main motivations linked to the study of these phenomena are the numerous applications resulting from them. For example, in the study of the propagation of a spray within a combustion chamber or for pharmaceutical applications. Their study is carried out by a theoretical, experimental and numerical approach. Each of these techniques faces its own limitations: in the numerical study, the treatment of the droplets resulting from the jet break is a limiting factor due to the size ratio introduced. This thesis manuscript presents the coupling between an Eulerian interface treatment method and a Lagrangian particle transport method, proposing a multi-scale approach to atomization. The numerical solver Archer is used to transport a two-phase flow and to study its evolution, solving the incompressible Navier Stokes equations. The interface separating the two phases is represented by a method combining precision and robustness, the Volume of Fluid/Level-Set coupling. The discretization of the Navier Stokes equations and the transport of the interface is presented in the first part of this manuscript. This introduces the weaknesses of this method due to the multi-scale aspect of the atomized jets: the low precision of the transport of the drops resulting from the secondary atomization. The second section of this manuscript is dedicated to the introduction of Lagrangian drop transport, different approaches are implemented and validated within the computational code Archer. Then, the coupling between the Eulerien and Lagrangian solver, validated from numerical experiments, is introduced. The latter aim to present the methodology implemented to validate the coupling while respecting the conservation of time and mass. This method is then applied to academic cases to introduce the parameterization allowing the junction between the Eulerien and Lagrangien solvers. Finally, the developed method is applied to the study of an atomized jet of crossflow configuration, used in gas turbine or ramjet. The results obtained demonstrate the possibilities related to the Eulerien/Lagrangien coupling, both on the physical and numerical aspects, opening up a model of drop breakup under Lagrangien transport
Fairhurst, Charles. "Contribution a l'amelioration de l'abattage mecanique de roches agressives : le pic assiste et le pic vibrant." Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0111.
Antoine, Yan. "Mise en œuvre de la fluorescence induite par laser couplée à la vélocimétrie laser a effet doppler. Application a l'étude et a la modélisation des propriétés diffusionnelles des écoulements turbulents." Nancy 1, 1999. http://www.theses.fr/1999NAN10047.
Gouy, Pierre-Alban. "Etudes spectrométriques de plasmas de rentrées atmosphériques (Mars-Terre) par torche plasma à couplage inductif à basse pression." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22608/document.
Many key technologies, to overcome some crucial steps, are needed for space missions. One of them concerns the re-entry: when the vehicle enters the atmosphere layer, its high velocity relative to the ground will generate significant friction and an increase in pressure. The kinetic energy of the object will be converted into heat energy and heat the gas forming a shock wave. Temperatures depend on the initial velocity, the atmosphere composition and its pressure. The gas is ionized and become plasma, it will therefore transfer its heat to the body of the probe not only by convection but also by radiation. To protect itself, the vehicle has a heat shield that can withstand extreme phenomena encountered during the descent. Additional constraints will impose a particular geometry and a heavy shield. So the goal is to have the lightest possible and effective protections to allow the probe to maximize its payload. For this, one of the key parameters is to know the behavior of the plasma and radiation produced during re-entry into the atmosphere. This thesis is positioned in this area of study: experiments to create a re-entry plasma are intended to be observed by a spectrometer
Ondet, Jérôme. "Adaptation d'une torche à plasma à couplage inductif à la détection de polluants dans les effluents des centrales thermiques." Clermont-Ferrand 2, 1998. http://www.theses.fr/1998CLF2A002.
Michel, Julien. "Développements numériques de la méthode SPH couplée aux Eléments Finis appliqués au phénomène de l'hydroplanage." Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0013.
This PhD thesis takes place in the Fond Unique Interministériel (FUI) HydroSafeTire project, dedicated to the study of the hydroplaning phenomenon. During a previous PhD thesis regarding this topic in the lab., the hydroplaning phenomenon has been investigated via a fluid/structure SPH/FE coupling, using the FE solver Abaqus developed by Simulia. Physical effects such as the water height, the velocity of the vehicle and the tire wear have been studied, showing that the tendencies experimentally observed were retrieved in the simulations. Therefore, it has been decided to use the FE structure solver specifically developed by Michelin for their tire applications, in order to take benefits of this solver for the specific hydroplaning problem. Then, in the present PhD thesis, the first step is the validation of the SPH/FE coupling, using this FE code, on academic test cases. The compromise between the accuracy of the results and the restitution time of the simulations is of paramount importance, particularly in an industrial context. Thus, three main topics are investigated in this work. Firstly, the consistency of SPH schemes using a Particle Shifting Technique (PST) is studied, in addition to a work on the PST itself. Then, a model of flow separation is proposed, compatible with suction effects. Finally, different coupling schemes SPH/FE using differed time-steps are studied, with an hydroplaning application