Dissertations / Theses on the topic 'Fatigue thermique – Transfert de chaleur – Modèles mathématiques'
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Guellec, Corentin. "Caractérisation en fatigue à grand nombre de cycles par mesures d’auto-échauffement des aciers d’arbres de transmission pour application navale sous chargements cycliques complexes." Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2023. http://www.theses.fr/2023ENTA0001.
Full textMarine shaft lines undergo complex cyclic loadings. In order to characterize these structures in fatigue, two complementary objectives are achieved. Firstly, the marine shaft’s loads are characterized in order to identify relevant fatigue cycles. During this step, an original parametric fatigue design method is implemented. This method is based on the definition of an equivalent load considering multiaxiality, variability, non-proportionality and mean stress. This method allows to distinguish two damage modes with a mode associated with the established cyclic regime of rotary bending and a mode associated with the ship’s maneuvers. Secondly, a rapid characterization method is implemented to characterize in fatigue the marine shafts’ steels for a large number of loading configurations. The method is based on a model which enables fatigue identification behaviors from self-heating measurements. The steels of the study are characterized in tension-torsion for various configurations of mean stress and nonproportionality of the loading. In this context, the notion of iso-self-heating surfaces is introduced. It allows, for a specimen, to model the elastoplastic and dissipative behavior of the material in the dedicated stress space. Their use makes it possible to define a multiscale fatigue criterion based on the invariants of the stress tensor. In the study, a modeling of the behavior of the material is proposed for very low amplitude loads (VHCF) exhibiting a strong difference in dissipation compared to the regime of higher amplitudes (i.e. HCF domain)
Berour, Nacer. "Modélisation du transfert de chaleur par rayonnement, conduction et convection : Application aux fours verriers." Nancy 1, 2005. http://docnum.univ-lorraine.fr/public/SCD_T_2005_0152_BEROUR.pdf.
Full textStudy of coupled heat transfer through radiation, conduction and convection has been carried out and detailed in this PhD memory. Non grey semitransparent media at high temperatures are studied. Acute description of involved physical phenomena leads us to develop several numerical methods for such materials. Radiative heat transfer equation (RTE), Navier-Stokes equations and energy balance are solved with the finite volume method (FVM). Analytical solutions cannot be considered for such problems owing to their complexity. Besides numerical treatment induces necessary approximation in order to rewrite characteristical equations describing the real problem. In the case of RTE modelling a new differencing scheme has been proposed, on the other side Navier-Stokes transport equations are solved with a modified QUICK scheme. Both techniques ensure efficient modelling. The achieved simulation codes have been used for glass melting process description. An enhanced model describes a float glass furnace behaviour, from the material feeding to the refined glass extraction
Louarn, Sylvain. "Études expérimentales et simulation numérique d'un procédé thermique de séchage : application au traitement des boues." Lorient, 2013. http://www.theses.fr/2013LORIS300.
Full textWithin an approach of wastes global valorization, sludge generated by municipal, industrial and agricultural wastewater treatment plants is mostly re-used in valorization processes. In most of the cases, these recycling processes first make it necessary to reduce significantly the water content in upstream sludge. Generally, the first step of this type of process is a mechanical dewatering phase followed by a thermal drying phase in order to reach a dry content of 80%. As dehydration is directly linked to the amount of energy brought to the product, it is necessary to develop a high energy efficient drying process. This thesis focuses on developing and validating a complete numerical tool for designing a heat pump assisted sludge dryer. The experimental setup within the LIMATB lead to the establishment of the drying kinetics of sludge plates submitted to convective and conductive heat intakes. Thanks to the analysis and the comparison of experimental data, the impact of operating parameters (air temperature, humidity and velocity, contact temperature) on the drying time and the product deformation can be observed. A coupled heat and mass transfer 1D model is validated by various experiments. The taking into account of an effective diffusion coefficient, which integrates the influence of cracks, has been proven relevant to access to the evolutions of temperature and water content gradients in the product. New drying scenarios with variable air conditions and product flipping have been simulated. Then, this model has then been combined to a global multizone tunnel dryer model. It integrates the circulation of sludge in the dryer and the evolution of air characteristics as it goes through each zone. Simulations permit to predict the dry content as a function of the air conditions in dynamic regime. Meanwhile, an additional computing module has been developed with a view to designing the heat pump system
Sahraoui, Nour-Eddine. "Contribution à l'étude en régime transitoire d'un nouveau modèle approché pour caractériser le comportement thermique d'un local : étude expérimentale des transferts dans les locaux." Lille 1, 1985. http://www.theses.fr/1985LIL10091.
Full textMichaud, Estelle. "Modélisation de l'évolution du champ thermique dans des tunnels ferroviaires longs interconnectés : application au tunnel sous la Manche." Valenciennes, 2003. http://www.theses.fr/2003VALE0026.
Full textIn order to know the thermal field and its time evolution in inter-connected long railway tunnels, we established a model taken into account all thermal transfers, as well as the principal source-sink terms. We develop initially the equations describing the occurring phenomena by detailing the whole of the heat sources as well as modeling chosen to represent them. A program was built to simulate these exchanges. We chose the method the finite differences to numerically integrate the conservation equations of energy. We have then to compare the simulation results with the measurements made in the Channel tunnel. The model selected makes it possible to simulate the changes of the temperatures on short term (a few days) if data inputs are precise, or on long term (several months at a few years) with the possibility of entering averaging data
Humbert, Laurent. "Modélisation thermique et cinétique du vapocraquage de mélanges gazeux légers." Aix-Marseille 3, 1998. http://www.theses.fr/1998AIX30005.
Full textThis memo describes the development of a steam-cracking furnace model to optimise furnace operating conditions. The model is a knowledge model using heat transfer laws, pressure drop equation and simplified kinetic reactions scheme. The coking model and its effects on furnace operations are taken into account in model. Coke is the principal constraint which reduces run length and decreases the selectivity of steam cracking operations. The first part of this report describes the literature and the existing tools. It presents also the version developed for Lavera old horizontal gas furnaces cracking. The second part is development, tuning and validation of the model for new vertical furnaces. The kinetic scheme from the previous version has been tuned by little adjustment of the kinetic constants. Heat transfer, pressure drop and coking models are updated with new laws to improve the results of the models and to take into account of the new technology of the furnace. Then, the model has been tuned on a large set of industrial data and validated following a sever procedure before use in simulation. Applications of the model, which are the justification of the work progressed, are described in the third part. The first application is to follow actual runs to check the running conditions of the furnace and to detect as soon as possible any unexpected event. The second application is optimisation of turn operating conditions to improve the benefit of the plant. .
Sfaxi, Youssef. "Contribution à l'étude numérique et expérimentale du comportement thermique des dalles chauffantes." Paris 12, 1987. http://www.theses.fr/1987PA120057.
Full textBaccar, Mounir. "Modélisation numérique tridimensionnelle du comportement hydrodynamique et thermique en cuve agitée." Toulouse, INPT, 1990. http://www.theses.fr/1990INPT001G.
Full textWang, Hao. "Contribution à l'étude thermique des contacts périodiques solide-solide." Vandoeuvre-les-Nancy, INPL, 2000. http://www.theses.fr/2000INPL040N.
Full textLazard, Myriam. "Modélisation macroscopique du transfert de chaleur transitoire couplé conduction rayonnement dans un milieu semi-transparent : estimation de paramètres." Vandoeuvre-les-Nancy, INPL, 2000. http://www.theses.fr/2000INPL030N.
Full textChahboune, Abderazak. "L'isomérisation du polyacétylène-cis au sein d'un film du polyacétylène-(cis,trans) sous l'impact d'un faisceau laser : modélisation cinétique et thermique." Montpellier 2, 1999. http://www.theses.fr/1999MON20093.
Full textVariot, Bruno. "Modélisation des transferts de chaleur par rayonnement dans les systèmes gaz-solide à haute température." Perpignan, 1993. http://www.theses.fr/1993PERP0165.
Full textDubus, Nicolas. "Contribution à l'étude thermique d'un réacteur à décharge à barrière diélectrique." Poitiers, 2009. http://theses.univ-poitiers.fr/theses/2009/Dubus-Nicolas/2009-Dubus-Nicolas-These.pdf.
Full textThis thesis aims to study the thermal behaviour of a laboratory Dielectric Barrier Discharge (DBD) reactor. An experimental study was first realized to measure temperatures at different points of the reactor by using optic fibres. These measurements were performed in transient and steady states. To examine the influence of heat losses , not insulated and insulated reactors were considered. The influence of the nature and the form of the applied voltage was else considered. Experiments were conducted with a sinusoidal voltage and a pulsed power supply
Guigon, Pierre. "Hydrodynamique d'un lit ruisselant de particules et transfert thermique associé : application au dimensionnement d'un échangeur industriel." Compiègne, 1987. http://www.theses.fr/1987COMPE067.
Full textThe hydrodynamic and thermal characteristics of solids raining through a tubular heat exchanger with or without the presence of a counter current flow of gas had been studied. A physical model was developed to predict the performance of raining bed heat exchangers. An example for designing a solids cooler was given to illustrate the calcu1ating procedures. The particles trajectories in the heat exchanger could be computed with the knowledge of three parameters : namely, the solids-solids friction coefficient, the solids-wall friction coefficient and the tangential coefficient of restitution on the tube. Various experimental set-ups had been designed to obtain these parameters. An inclined chute of short length was constructed to study the heat transfer coefficient between the flowing solids and the wall. The coefficient appeared to depend mainly on the solids concentration at the wall, which is a function of average velocity and mass flow rate of solids. On the heat exchanger tube surface, two different zones were observed. The raining particles exchange heat directly with the upper surface of the tube. Additional heat is exchange through gas convection and radiation on the remaining tube surface. Heat transfer coefficients were obtained for various types of solids under different operating conditions – Criteria for optimum design were proposed
Goyheneche, Jean-Marc. "Modélisation et caractérisation thermique à très haute température de matériaux poreux en carbone destines à l'isolation des corps de rentrée dans l'atmosphère." Lyon, INSA, 1997. http://www.theses.fr/1997ISAL0043.
Full textThis research work consists of three parts. An analytical and numerical first part demonstrates that a diffusion model is very well adapted to the modelling of radiative-conductive coupled heat transfer in carbon porous materials. This model features an apparent conductivity which represents the radiative and conductive exchanges in the medium. Radiative transfer is strictly modelled herein using the HOTTEL Zone Method, the latter being extended to anisotropic scattering media in order to be applied to the problem. An experimental second part deals with carbon porous materials characterization. Apparent conductivity measurements are performed from 20°c to 500°c using the flash method, and from 1000°c to 2800°c using a modulated technique. A thorough study is developed from this experimental device. An experimental set-up for the measurement of spectral (1 0. 6 µm) radiative properties of carbon porous materials is performed. Then, in order to validate all the study, a fourth experimental system is devised to simulate thermal behavior of carbon porous materials in operational conditions. The third part deals with the characterization of some carbon porous materials. Conductivity measurements indicate the progressive influence of radiative exchanges into the medium when its temperature rises. Besides the difficulty encountered in measuring radiative properties of carbon porous materials shows the relevance of a global approach. Finally, experimental and numerical simulations of the thermal behavior of these materials in operational conditions lead to a critical analysis of results
Wang, Xi. "Prédiction et analyse numérique d’écoulements turbulents avec transfert thermique dans des cavités ventilées à l’aide d’un modèle à relaxation elliptique." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10075/document.
Full textThe aim of this work is to predict numerically turbulent airflow with heat transfer in indoor environment using an elliptic relaxation model. This approach named v² -f has been proposed for modelling near-wall turbulence. In this study, numerical investigations have been carried out in three configurations and validated on available experimental data and numerical results from the models considered, k -[epsilon]RNG model of Yakhot & Orszag, k -[omega] SST model of Menter and Reynolds stress model. The analysis and comparison of results obtained shows that the v² -f model provides a better prediction for the velocity fields and temperature fields with a reasonable computational time. All comparisons of thermal comfort indices suggest that
Mauriès, Sébastien. "Caractérisation et modélisation de la séquence de précipitation de carbures au cours du traitement thermique d'aciers martensitiques alliés." Toulouse, INPT, 2008. http://ethesis.inp-toulouse.fr/archive/00001195/.
Full textMartensitic steels containing 5% chromium, mainly used for forging and high-pressure die casting tools show limited lifetime due to severe thermo-mechanical working conditions. The resistance to stress at high temperatures is directly related to the stability of nanometer sized alloyed cabides which are formed beyond 450°C during tempering. The study aims to characterize alloyed carbides in the early stages of tempering and determine how the sequence of precipitation is changed. In that way, carbides forming elements (V, MO) as well as influencing the precipitation (NI, CO) were added to change the precipitation of a low-silicon AISI H11 steel previously studied, especially at temperatures near the peak hardness
Tupinier, Françoise. "Intégration dans la bibliothèque Modulef d'éléments de plaque épaisse : application de l'homogénéisation à une plaque d'échangeur thermique." Lyon 1, 1985. http://www.theses.fr/1985LYO11674.
Full textCourivaud, Jean-Michel. "Étude des transferts couplés de masse et de chaleur en milieu poreux : application à la cuisson par vapeur saturée d'un béton cellulaire." Toulouse, INPT, 1993. http://www.theses.fr/1993INPT082H.
Full textGendarme, Jean-Philippe. "Développement d'un contacteur/échangeur à lit transporté vibrofluidisé." Compiègne, 1992. http://www.theses.fr/1992COMPA001.
Full textHydrodynamics of continuous and discontinuous beds of mono and polydispersed sand conveyed in a helicoïdal vibrating elevator have been studied. We took into account, in a mecanistic modeling of a vibrating bed of solids, the gas/ solid interaction force created by a transient pressure gradient between the bed ends to estimate the average transport speed to ± 30 % in most cases. A dimensionnal vibratory acceleration is the main design parameter for transport speed, at constant particule diameter. The influence of the main vibratory parameters (frequency and amplitudes) and of the solids bed (thickness, particule mean diameter) on the wall/bed heat transfer coefficient has been studied experimentally. Due to vibration, the improvement of heat transfer intensity has been demonstrated by using a simplified model integrating the gas / solid interaction force (rigid vibrating bed hypothesis). As an example, we have briefly discussed the correlation of transport and heat/mass transfer in a vibrating heat exchanger used for absorption (fluidized bed) / desorption (vibrating bed) of water vapor on calcium sulphate in a continuous cycle. It's possible to intensify the internal movements of solids convection by using a tubular transport trough. A few preliminary experiments show a heat transfer coefficient improvement of almost 50 % when compared with the result obtained in a rectangular trough. A maximum coefficient of 215W /m2oc has been measured. Due to tubular geometry simplicity, interesting applications in jacketed or direct conduction heating (Joule effect) in vacuum or pressure service should be possible
Maliwan, Kittinan. "Modélisation de l'action des vibrations sur les écoulements de convection thermique ou solutale en milieux poreux." Toulouse 3, 2004. http://www.theses.fr/2004TOU30137.
Full textThe present work, we study analytically the effect of the action of high-frequency vertical vibration on the onset of the convective motion in mono and multi-component fluids in porous media. The geometry considered is a "Rayleigh-Bénard" configuration. Generalized Darcy-Brinkman mathematical model is taken into account to describe convective flows. In the framework of Oberbeck-Boussinesq approximation, the induced convective motion due to temperature field or concentration field in the presence of gravitational and vibrational fields are studied by using time-averaged method. In the first part of this work, the case of porous media saturated by pure fluid is considered. The critical parameters are found by applying Galerkin method. The asymptotic analysis is also performed to obtain an analytical relation in the case of small Darcy numbers. It is shown that high-frequency vertical vibration can delay convective instabilities and, in this way, reduce the convective flow. In the case of very small Darcy numbers, the weakly non-linear analysis is then carried out to obtain an expression for Nusselt number. .
Zély, Didier. "Modélisation des thermoéléments à effet Peltier. Application à l'analyse thermique d'un instrument pour expérimentations en conditions spatiales." Toulouse 3, 1992. http://www.theses.fr/1992TOU30256.
Full textBouneder, Mohamed. "Modélisation des transferts de chaleur et de masse dans les poudres composites métal/céramique en projection thermique : application à la projection par plasma d'arc soufflé argon hydrogène." Limoges, 2006. https://aurore.unilim.fr/theses/nxfile/default/dc7476e0-d0ed-4c31-8047-ced37abb1d3d/blobholder:0/2006LIMO0021.pdf.
Full textThe aim of this work is the modelling and the investigation of heat and mass transfer for in flight composite metal/ceramic particles (obtained by mecanofusion process) and sprayed in Ar-H2 75-25% vol. Arc-jet DC plasma. The use of coated powder has the potential for producing metal matrix composite MMC coatings. To date, the thermal behaviour of these coated powders has not been studied yet. The thermal modelling presented, apply to the spraying process under low loading conditions and the numerical solution is based on enthalpy formulation and finite volume discretization technique of the second order in time and space. A thermal contact resistance TCR based on the volume solid fraction of the materials under consideration is proposed, to take into account solid-liquid phase transition. The thermal behaviour of the composite particle in the jet and within the trajectories is investigated and the influence of the main parameters like the size of the particle, physical nature of the materials, and thermal resistance of contact are clearly identified. Finally, some numerical results are obtained, which are in agreement with experimental results previously obtained by SPCTS laboratory ot Limoges University
Audet, Denis. "Stockage thermique par containérisation alvéolaire de M. C. S. Et M. C. P. : mise en oeuvre d’un évaporateur / stockeur." Compiègne, 1985. http://www.theses.fr/1985COMPI212.
Full textBouhouch, Ahmed. "Modélisation des écoulements monophasiques et des transferts de chaleur en milieux poreux : situations transitoires à masse volumique variable et à haute température." Toulouse, INPT, 1996. http://www.theses.fr/1996INPT045H.
Full textLe, Coroller Hervé. "Effet de la conductivité thermique sur la structure des ondes de choc radiatives : étude de la pulsation de deux étoiles super-géantes froides HD 56126 et HD 179821." Aix-Marseille 1, 2002. http://www.theses.fr/2002AIX11028.
Full textShuai, Xiaoshan. "Transfert thermique convectif en régime laminaire pour des fluides visqueux à forte dépendance thermorhéologique : cas des écoulements stationnaires et pulsés." Compiègne, 1987. http://www.theses.fr/1987COMPD073.
Full textManin, Lionel. "Modèles de comportement multiniveaux pour la Conception Mécanique Assistée par Ordinateur : application à la prévision du comportement thermique de transmissions de puissance par engrenages." Lyon, INSA, 1999. http://theses.insa-lyon.fr/publication/1999ISAL0019/these.pdf.
Full textThe aim of Computer Aided Design in mechanics is to design products with a maximum constraints integrated in the design process. The main aim is to predict as closest as possible the mechanism behavior in order to optimize its design. Numerical modeling provides results in several fields (static's, dynamics, thermal behavior…), in this work, we have considered the thermal behavior of a system at its preliminary design step. The actual trends of saving weight in order to increase efficiency reduce the heat dissipation capacity and consequently create a rise of the mean operating temperatures which must be integrated in the design process. The application in this work deals with the thermal behavior prediction of power gearing transmissions. The originality of this work comes from the simultaneous application of global and local approaches. First, a bibliographical study has been done in order to set down the bases of the work, and to make a census of the different existing approaches and modeling studies of the thermal problem in power gearing transmissions. Then, a methodology of thermal behavior modeling of a generic power gearing transmission has been developed. A global thermal model has been achieved using the thermal network method; it is composed of local models defined for each technological class of elements. Experiments on industrial test bench were carried out in order to validate the numerical approach. Finally, the established procedures were applied in order to provide thermal behavior prediction in several cases for mechanical design
Razi, Yazdan Pedram. "Contribution à l'étude de l'action des vibrations sur les écoulements de convection thermique ou solutale en présence ou en l'absence de gravité." Toulouse 3, 2004. http://www.theses.fr/2004TOU30234.
Full textIn the present work, we study the effect of the action of mechanical vibration on the convective motion in mono and multi-component fluids in the presence or in the absence of gravity. In the framework of the Boussineq approximation, the induced convective motion due to the temperature field in the presence of gravitational and vibrational fields are studied. In the first part of this work, the linear and weakly non-linear stability analysis of Horton-Rogers-Lapwood problem under the effect vertical vibration (parallel to the temperature gradient) has been carried out. Two different approaches (time-averaged and direct methods) are used to study the thermal stability analysis of this problem. By applying the results obtained from the scale analysis method to the coefficients of the Mathieu equation, the criteria for comparing the results from these two stability analysis approaches are found. In the second part of this work, the influence of directions of vibration of high frequency and small amplitude on the onset of Soret driven convection is addressed. The linear stability analysis in an infinite horizontal layer filled by a binary mixture is performed. The stability of quasi-equilibrium solution for an arbitrary direction of vibration in the presence or in the absence of gravity for long wave mode is then examined. For this case, an analytical relation giving the critical parameter is found. .
Benabderrahmane, Yacine. "Modélisation dynamique et thermique d'écoulements diphasiques solide-liquide en présence d'effets non locaux et application au chauffage ohmique de mélanges agro-alimentaires." Compiègne, 2001. http://www.theses.fr/2001COMP1351.
Full textRavary, Serge. "Etude du comportement thermique des pistons de moteur diesel automobile : modélisation, expérimentation, analyse système du moteur." Poitiers, 1997. http://www.theses.fr/1997POIT2276.
Full textVinsard, Gérard. "Modélisation de l'électromagnétisme et des transferts thermiques couplés dans le cadre du chauffage par induction : application à la simulation d'un procédé industriel." Vandoeuvre-les-Nancy, INPL, 1990. http://www.theses.fr/1990INPL017N.
Full textRammal, Dina. "Thermo-mechanical behaviour of geothermal structures : numerical modelling and recommendations." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10172/document.
Full textGeothermal structures act as heat exchanger elements in addition to their major role as bearing structures. Thus, they are subjected to thermal solicitations as well as to mechanical loading. However, their design methods are not clearly defined yet. This work is divided into two main parts that cover the thermal and mechanical design of thermo-active piles and diaphragm walls. Regarding the thermal performance of geothermal structures, two strategies are introduced that are capable to evaluate the allowable exchanged conductive and advective energies. They help to distinguish between different forms of exchanged energies and show how they may vary under cyclic thermal loading. Two and three dimensional hydro-thermal numerical models have been conducted and the thermal performance of geothermal structures has been evaluated based on the two presented approaches. Regarding the mechanical design, this work covers the issues related to the choice of the thermal solicitation that the designer has to consider for the mechanical design of geothermal structures such as the number of cycles, cyclic thermal amplitude, and influence of the thermal loading order. This work deals with these issues with the aim to facilitate the design of geothermal structures. Recommendations are given for the mechanical design of both thermo-active piles and diaphragm walls based on the results obtained from the thermo-mechanical numerical analyses
Bendouma, Mathieu. "Systèmes d’isolation thermique par l’extérieur : études expérimentales et numériques des transferts de chaleur et d’humidité." Thesis, Lorient, 2018. http://www.theses.fr/2018LORIS485/document.
Full textExternal thermal insulation (ETI) is an interesting technical solution for improving the energy performance of the building sector. However, ETI may change the hygrothermal balance of the envelope and affect its durability, especially with regard to moisture. With this in mind, a first work consisted in studying the hygrothermal behavior of three systems of ETI set on a hollow concrete block wall in the laboratory: an ETICS system (wet process) and two systems under cladding (dry process), with one of them composed with bio-based materials (wood wool and cellulose wadding). Experiments in a bi-climatic enclosure, combined with numerical simulations of coupled heat and mass transfers, made it possible to apprehend the hygrothermal behavior of these renovated walls at different stages: during the installation of ETI solutions, in "normal" use and under conditions leading to risks of condensation. The results of the ETICS system show the important role of the glue and the difficulty to understand numerically its behavior. The results of the cladding systems underline the interest of using bio-based materials under hazardous conditions, but also the sensitivity of numerical simulations to the hydric properties of hygroscopic materials. A second study on the in situ analysis of a cladding ETI system highlighted the absence of major risks related to humidity during the two years studied. In addition, the simulation / experiment comparison highlighted the important role played by the ventilated air
Moissette, Sophie. "Étude dynamique et thermique par modélisation eulérienne-lagrangienne des effets liés aux interactions turbulence-particules dans un écoulement gaz-solide en conduite verticale non-isotherme." Nancy 1, 2001. http://docnum.univ-lorraine.fr/public/SCD_T_2001_0231_MOISSETTE.pdf.
Full textThe present study aimed at contributing to the development of simulation tools for turbulent gas-solid non-isothermal flows, which are present in numerous industrial applications (drying processes, combustion, ). The modelling is implemented in the frame of an Eulerian-Lagrangian approach and leans on a fine representation of the mechanisms able to affect the suspension behaviour (anisotropic low-Reynolds k-epsilon closure model and WET closure model, stochastic particle tracking with collisions and dispersion, coupling between the phases). The influence of the various phenomena and their modelling on the behaviour of each phase is estimated by several parametric studies and by comparisons with results from the literature. The calculation code turned out to be able to predict the heat exchange modulation in the presence of particles for a relatively wide range of flows, even if several problems still arise for the smallest particle sizes and for the strongest mass loading ratios
Ferahta, Fatima Zohra. "Etude du transfert thermique dans la lame d'air d'un capteur solaire." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4754.
Full textThis thesis aims to study the solar thermal collectors. Thus, we seek to understand the mechanisms of natural convective heat transfer in the air gap of a solar collector, in order to find an optimal design which allows adequate thermal control and energy performance.Part of this thesis is devoted to the numerical simulation using fluent, based on the development of natural convection model in an inclined parallelepiped air gap of solar collector. Fluent CFD software is based on the finite volume method. The simulations were carried out to determine the velocity and temperature fields under the effect of the air gap thicknesses, the heat flux provided to the absorber and the presence of obstacles in the air gap. The results show the effect of the air gap thickness on the flow regime, which can be steady or unsteady. These simulations were performed with and without the coupling of convection-radiation in the air gap. Values of the coefficient of heat transfer was calculated for different cases and a comparison for both cases with and without taking into account radiation was made. The numerical study was followed by an experimental work based on the study of solar collector. To reduce heat losses, experiments were carried out to evaluate the thermal behavior of solar collector under external conditions (sunshine, temperature...etc) and the coolant flow rate for various gap air thicknesses. The results show the effect of the air gap thickness on the thermal performance and the importance of having an optimum thickness for better performance. Similarly, the introduction of barriers also contributes to improve the performance of the solar collector
Rubiolo, Pablo. "Modélisation du transfert thermique dans un milieu poreux : application aux réacteurs nucléaires en situation accidentelle." Aix-Marseille 1, 2000. http://www.theses.fr/2000AIX11055.
Full textVon, Bandel Sylvie. "Traitement thermique rapide et localisé de trempe et de cémentation des aciers par bombardement électronique : étude structurale et analytique." Compiègne, 1992. http://www.theses.fr/1992COMPD558.
Full textHachem, Elie. "Stabilized finite element method for heat transfer and turbulent flows inside industrial furnaces." Paris, ENMP, 2009. http://pastel.paristech.org/5656/01/EH-These.pdf.
Full textThe development of efficient methods to understand and simulate conjugate heat transfer for multi-components systems appears in numerous engineering applications and still a need for industrials, especially in the case of the heat treatment of high-alloy steel by a continuously heating process inside industrial furnaces. The thermal history of the load and the temperature distribution in the furnace are critical for the final microstructure and the mechanical properties of the treated workpieces and can directly determined their final quality in terms of hardness, toughness and resistance. The main objectives of this thesis is then to understand and better model the heat treatment process at the same time in the furnace chamber and within the workpieces under specified furnace geometry, thermal schedule, parts loading design, initial operation conditions, and performance requirements. The Computational Fluid Dynamics (CFD) simulation provides a useful tool to predict the temperature evolution and such processes. In the first part of this work, various stabilized finite element methods required for computing the conjugate heat transfer and the incompressible flows are proposed and analyzed. Two turbulence models, the k-epsilon and the Large Eddy Simulations (LES) models were introduced and used to simulate and take into account the complex turbulent flows inside the furnace chamber. The effect of thermal radiation was appropriately accounted for by means of a volumetric model known as the P1-model. In the latter part of this work, a multidomain approach referred as the immersed volume method (IVM) is introduced and applied to treat the fluid-solid interactions. It is based on the use of an adaptive anisotropic local grid refinement by means of the level-set function to well capture the sharp discontinuities of the fluid-solid interface. The proposed method showed that it is well suited to treat simultaneously the three modes, convective, conductive and radiative heat transfer that may interfere in both the fluid part and the solid part using anisotropic finite element meshes
Pham, Anh Thu. "Caractérisation aéraulique et thermique au sein d'un empilement de produits dégageant de la chaleur : application au cas des palettes de fromage." Thesis, Paris, Institut agronomique, vétérinaire et forestier de France, 2019. http://www.theses.fr/2019IAVF0010/document.
Full textCheese, like any fresh product, must be kept at a low temperature throughout the cold chain. A particularity of soft cheeses (Camembert, for example) is that they generate a significant amount of heat due to the respiration of the microorganisms. From a thermal point of view, cold air must flow within a cheese pallet to remove the heat released in order to achieve better production temperature control. From an airflow point of view, heat generated by the product induces natural convection inside the pallet. Several convection modes are therefore present: the forced convection imposed by the fans of the cold room around the pallet and the mixed convection, combination of forced and natural convection, inside the pallet. This therefore increases the complexity of the airflow. The mixed convection regime appears mainly at low fan speed which is often the case during storage. In addition, the system is influenced by many parameters: the orientation of the pallet, the opening area of the cartons, the blowing speed, the heat flux...The aim of the PhD is to provide inner knowledge on air flows and heat transfer within pallets of heat-generating products with low ventilation. This knowledge also aims to answer industrial problems. The PhD’s results should contribute to improve the design of vented cheese packaging and palletizing methods, which is currently done empirically. It should also be noted that the scientific topic addressed in this project related to aerodynamic and thermal interactions between forced and natural convection around and within the pallet has applications in other areas such as the cooling of electronic circuits.The PhD consists of two main parts: an experimental and a numerical study. In the experimental approach, a full scale pallet was built in which the products were replaced by plaster blocks inserted with heating resistance to simulate the heat flow generated by cheese. The experiments were carried out in a controlled temperature and air velocity room for two air inflow velocities: 0.31 and 0.73 m.s-1, three heat fluxes: 0.05 W, 0.15 W and 0.30 W per product (0.25 kg) and two orientations of the palette. The use of a laser Doppler velocimetry (LDV) and a hot-wire anemometer allowed characterizing airflows (velocity profiles, air flow rate in the vent holes) according to the air inflow velocity and the heat flux. The implementation of 200 thermocouples distributed throughout the experimental set-up also made it possible to obtain the temperature levels of the air and the products within the pallet according to these same parameters.The numerical study was performed by two approaches: a detailed model by computational fluid dynamics (CFD) with several millions of elements and a zonal model (about twenty zones) assimilating the system to a hydraulic network. Both models were validated using experimental data. The CFD gave complement information which is not accessible by the experimental measurements, which facilitated the understanding of the phenomena. The zonal approach, by its simplicity of use and its low computing time is more suitable for an industrial use
Thiry-Muller, Aurélien. "Modélisation de la décomposition thermique des solides." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0294/document.
Full textThe work presented in this thesis focuses on understanding, describing and finally modelling the degradation, under heat exposure, of commonly used furnishing materials (mainly natural or synthetic polymers). This is not a new research field, as many models exist nowadays (such as Arrhenius models associated with varied kinetics functions). However, unlike for development related to gas phase chemical kinetics, most current solid phase chemical kinetics related models suffer from insufficient theoretical backgrounds. Moreover, laboratory experiments, more precisely small scale ones, reveal some behaviours, that are not only unpredicted by current model, but also invalidate some of the underlying assumptions these models are based on. This work context is more precisely related to solid anaerobic decomposition, at small scale, for mass in the range of one milligram, in order to focus on both mass loss kinetics and, to a lesser extent, on thermal transfer in solid phase. This work was structured into three main sections, each of them being a chapter of this thesis. First part concerns numerous experiments based on experimental plans and performed with a thermogravimetric analyzer (TGA). This aims at, on the one hand, determining most influent variables on thermal decomposition, and, on the other hand, identifying behaviour discrepancies between experimental data and predictions of current models available in the literature. Test campaign main result is that there is no mass convergence with TGA, even for very low masses. In addition, the effect of both heating rate and solid phase dilution were explored. This led to some behaviours significantly different from theoretical predictions. Second part concerns the modelling of material thermal degradation in a TGA analysis. It also highlights problems related to heat transfer inside solid material. It is demonstrated in this work that Dirichlet boundary conditions, which are usually used to describe TGA device, are not adequate to reproduce such experimental specificities. Third and last part is dedicated to the elaboration of a kinetic model relying on assumptions specific to the solid phase. First and foremost this model is on based on Eyring’s work on transition state theory. Then exploring thermodynamic formalism related to transition state allowed the formulation of a new model of thermal degradation called “outside Ellingham assumption”. This model is compared to two commonly used ones, so-called (A, E, 1) and (A, E, n) and led to best prediction for single reaction mechanisms. Finally, the prospects inspired by this work concern, first, a better characterisation of thermal boundary condition in TGA, in order to be able to reproduce experiments by modelling. Secondly, it may be relevant to extend the develop model to multiple reaction mechanisms, in order to increase its predictive capabilities for the targeted applications
Loussouarn, Thomas. "Maîtrise de la thermique des fours de maintien en fonderie." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0105.
Full textVacuum holding induction furnaces are used for the manufacturing of turbine blades by loss wax foundry process. Heat transfer control in a holding furnace is crucial to ensure the quality of manufacturing. This work has 3 major parts, which are the detailed modelling, reduced modelling and experiments. An axyisymmetric furnace and its load have been numerically modelled using FlexPDE and COMSOL Multiphysics, finite element codes. Modelling takes as inputs the electric power consumed by inductors and gives the temperature field in the heating module. The studied reduced models are phyisical convolutive models (enthalpic (0D), 1 dimension analytical (1D)) and parametric like AutoRegressive with eXogeneous inputs (ARX). ARX models have been compared to convolutive models (identification, validation). The goal is to get temperatures in the heating module without local presence of physical sensors (virtual sensor). Detailed and reduced models have been compared to experiments on the furnace. This last part is not described in this document
Abdallah, Ghassan. "La convection thermique dans les milieux fracturés : modélisation avec la méthode des éléments distincts." Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL126N.
Full textKeruzoré, Nicolas. "Caractérisation thermique de l'équipement roue et frein aéronautique hautes performances par voies théorique numérique et expérimentale." Thesis, Paris 10, 2018. http://www.theses.fr/2018PA100127.
Full textFor the equipment manufacturer who develops aircraft wheels and brakes, the thermal behavior of the equipment refers to a major reference design point. This discipline is today at the center of concerns, because the designer is challenged on the system mass improvements. As a result, the temperature limits are more frequently reached, which must now be anticipated as early as possible.The pre-design phase should now also allow avoiding design iterations. However, the conditions under which the system operates and its thermal behavior, are poorly understood and poorly controlled. The predictive nature of the numerical simulations used to design the structure, depends directly on the model’s accuracy and on the in service boundary conditions imposed to the system.Today, Safran does not have any enough reliable tool or means to predict the thermal behavior of the Wheels & Brake assembly right from the pre-design phase. It is known that the design of the brake and the wheel have a reciprocal influence on the thermal kinetics of the system. Knowing how to predict the thermal behavior of the product, in response to stresses requested by the aircraft manufacturer, allows upstream technological choices whose impact on the thermal kinetics will be known. Thus, the design is disregarded of possible design iterations that could delay the aircraft certification by several years.The purpose of this thesis is to propose solutions to qualitatively reproduce the thermal behavior of an aircraft braking system, taking into account physical parameters associated with technological solutions. We also illustrate that these tools are also a way of knowing the conditions under which the system operates, when one knows in advance its temperature response by taking the problem in the opposite way
Djibrilla, Saley Abdoulazizi. "Tomographie hydraulique des milieux poreux hétérogènes à partir de traçage thermique : approches expérimentales." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR102/document.
Full textThe importance of issues related to the quality of groundwater requires characterizing the operation of groundwater aquifers. Hydrogeological methods used to carry out conceptual model of an aquifer are generally based on the observation and characterization of the medium, by using boreholes and carrying out of pumping test operations. However, these methods present some limitations in characterizing the spatial variability of heterogeneous aquifers. In this thesis, we develop experimental approaches that use information from thermal or saline tracing for the characterization of hydraulic parameters in heterogeneous porous media. The choice of using experimental approaches was justified 1) by difficulties of taking into account hydraulic heterogeneities in natural porous media and 2) for a better understanding of the phenomena involved in a controlled situation. In this work, we first proposed the use of punctual thermal measurements, then measurements obtained by using thermal infrared to estimate hydraulic parameters in heterogeneous porous media. However, as thermal tracing methods are limited in low permeability areas, we improved our approach by combining it with a geophysical method (Spontaneous Potential). This method, sensitive to fluid flows and thermoelectric and electrochemical processes, has allowed us to collect interesting temporal data to monitor thermal or saline variations in the media. The measurements obtained were then used in inversion algorithms to estimate the spatial distributions of hydraulic properties. The results obtained allowed to demonstrate the effectiveness of these approaches for the characterization of heterogeneous media and consequently for the modelling of fluid flows
Guedia, Guemo Gilles Romuald. "Modélisation et caractérisation thermique de machines électriques synchrones à aimants permanents." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0023/document.
Full textPermanent magnet synchronous machines are likely to break down due to poorly controlled heating. The goal of this study was to develop a generic and predictive thermal model to calculate the temperature of machines during the design phase simulating temperatures at various states. These states include: steady state, transient state, fault mode, axial circulating of a cooling fluid in the air-gap and high speed. The lumped parameter method was used to develop this generic thermal model. Meanwhile, a test bench and a prototype instrumented with thermocouples were manufactured to validate the model at the same time. Sensitivity studies of the results of the model to some parameters demonstrated that some convective coefficients, contact conductances and the thermal conductivity of the winding in the radial direction influenced the model. However, these parameters are poorly known, because empirical formulas or abacus are used to calculate them. Using, the prototype and the developed model, these parameters were identified. Three methods of identification were tested in order to find a strategy for the identification: the genetic algorithms method, the Gauss-Newton method and the Levenberg-Marquardt method. Many tests were done on the prototype. The measure of the temperatures on the specific place allows to identify these parameters and to validate the model
Tadé, Valentina. "Modélisation de la variabilité spatiale et temporelle de la température de surface pour un sol homogène avec relief." Phd thesis, Université de Provence - Aix-Marseille I, 2004. http://tel.archives-ouvertes.fr/tel-00084669.
Full textL'approche 1D développée pour les modèles simplifiés consiste à exprimer la température en un point de la surface du sol avec relief comme une combinaison d'une température "ombre" et d'une température "soleil" du sol équivalent plat horizontal. Les phénomènes prépondérants de la variabilité de la température sont isolés par la réalisation de mesures en extérieur sur une maquette à profil sinusoïdal. Les mesures obtenues permettent de valider le code thermique 3D de référence.
Différents modèles analytiques 1D sont développés et validés par rapport à ce code. L'application de la méthode "ombre/soleil" par passage dans l'espace de Fourier conduit à une bonne concordance entre le modèle et la solution de référence 3D.
Maachou, Vaxelaire Asma. "Identification par modèle non entier non linéaire : application à la modélisation de la diffusion thermique." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14725/document.
Full textLinear fractional differentiation models have proven their efficacy in modeling thermaldiffusive phenomena for small temperature variations. However, for large temperature variations,the thermal parameters are no longer constant but vary along with the temperatureitself. Consequently, the thermal system could be modeled by non linear fractional differentialmodels. Volterra series are first extended to fractional derivatives. Volterra seriesare then used for modeling a non linear thermal system, constituted of an ARMCO iron sample,for large temperature variations
Munaretto, Fabio. "Étude de l'influence de l'inertie thermique sur les performances énergétiques des bâtiments." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2014. http://pastel.archives-ouvertes.fr/pastel-01068784.
Full textNoba, Ibrahima Sory. "Modélisation et simulation numérique du comportement de chargement de gaz naturel liquéfié dans une cuve de méthanier." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0312.
Full textThe evaporation process of Liquefied Natural Gas (LNG) in LNG vessel tanks is closely related to heat infiltration through the walls of the insulation and also to the sloshing of the liquid in the tank. Most of the models developed give predictions assuming a constant evaporation rate or BOR Design. Real evaporation depends on many more physical parameters because LNG is a multi-component mixture consisted essentially of methane, stored at its boiling point of about -161 °C at atmospheric pressure. A detailed zero-dimensional (0D) dynamic tool that enables one to evaluate the thermal transfers and thermodynamic properties in LNG carrier tanks has been developed. The model is used to investigate the variation of the LNG and BOG quantity, composition and thermodynamic properties during typical voyage profiles of a case study LNG carrier or Operational BOR concept. The principle of the operational Boil-Off Rate (Operational BOR in this paper) is different from the design BOR. The design BOR is a benchmark of the thermal performance of the insulation under standard environmental conditions in a stationary configuration, translated into daily evaporation rate for pure methane. Conversely, the Operational BOR which is an unsteady calculation of the thermal and thermodynamic state of LNG, is designed to measure the amount of boil-off gas produced during the navigation taking into account the actual environmental conditions. A correlations studies carried out in the model gave results with relative errors between 2% and 5% of natural BOG between observation and simulation