Дисертації з теми "Dynamique des fluides – Essais (technologie)"
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HADJ-SADOK, CHIKH. "Forces fluide-elastiques dans un faisceau de tubes soumis a un ecoulement transversal." Paris 6, 1994. http://www.theses.fr/1994PA066384.
Повний текст джерелаBarkallah, Amine. "Membranes et systèmes pour le contrôle des échanges de fluides dans un boîtier électronique : essais et modélisation." Montpellier 2, 2009. http://www.theses.fr/2009MON20048.
Повний текст джерелаIn this thesis we studied the impact of the application of breathing membranes on protecting boxes of calculators embarked in a car. For that, a comprehensive experimental and theoretical study was developed in order to understand the whole phenomena of mass and heat of transfer controlling the exchanges of fluids in response to changes of external and internal environmental conditions (temperature, pressure, relative humidity and vapour partial pressure). A complete characterization of the membranes by static and dynamic techniques made it possible to specify the structure of the membranes and thus to obtain full structural and morphological parameters necessary to modelling. Thereafter, a model was developed based on an in series resistances approach by considering the influence of the boundary layers on the global transfer and by coupling mass and heat transfers in the whole system. The model was validated by matching the simulation curves with experimental results carried out with an actual and a reference box under various operating conditions. Conclusions on the choice of these systems and their dimensioning were then defined and the limitations of their uses were identified. One of the problems encountered during the use of a breathing membrane was the increase of relative humidity within the case. The developed and validated model can thus be used as predictive tool and as a sizing tool of the system
Podeur, Vincent. "Modélisation expérimentale et numérique du power take-off d’un bassin houlomoteur." Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0005.
Повний текст джерелаThe present work aims at studying the power take-off of a wave energy converter (WEC). This system is composed of a set of connected tanks. Rubber flaps are installed at tanks inlet and outlet to ensure a one-way flow direction. Thanks to wave induced motions of the supporting platform, sloshing appears inside the WEC tanks which feed a cylindrical basin with a centered drain hole at its bottom. Then, a bathtub vortex flow appears within this tank, where a vertical axis turbine is installed to harvest kinetic energy from the flow. The first phase of this research focuses on studying the steady bathtub flow. To do so, a dedicated experiment is built. Velocity field within the cylindrical basin, with and without the turbine, is studied via Particle Image Velocimetry (PIV). In addition, power production from the turbine and water level inside the tank are measured. These results are used to define starting hypothesis for developing a numerical model of the turbine. The second phase of this research focuses on studying the unsteady bathtub flow. For this purpose, a second experiment is built. This setup provides a more realistic environment, closer to what can be observed with the WEC system. PIV measurements are also used extensively to study the flow with and without the turbine. The last stage of this research focuses on the numerical modelling of the vertical axis turbine. The model is based on the potential flow theory. First, a two-dimensional approach is used to validate the early pieces of the model. Secondly, a three-dimensional approach is adopted to account for more complex flow features. Finally, numerical and experiment results are compared
Balducchi, Franck. "Analyse expérimentale des paliers et des butées aérodynamiques à feuilles." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2318/document.
Повний текст джерелаThis document deals with the experimental analyses of two types of air lubricated aerodynamic components: foil journal bearings and foil thrust bearings. These components belong to a new generation of bearings, and are well worth integrating in turbomachinery, which performances are at stakes. Indeed they enable to reach very high speeds without any wear in continuous regime and they diminish energy loss compared to oil bearings. This memoir is a contribution to these two elements, which maturity levels are different.A test rig dedicated to the study of foil thrust bearings under both static and dynamic loads is designed. Start-up characteristics show a linear increase of start-up torque with static load, a linear increase of the fluid film torque with both static load and rotation speed, and an increase of lift-off speed with rotation speed. Dynamical tests show a non linear increase of the stiffness with both excitation frequency (between 150 Hz and 750 Hz) and static load. Equivalent viscous damping decreases with excitation frequency, but increase with static load. Loss factor decreases with excitation frequency and increase with static load.An existing test rig was modified to test foil journal bearings, in a close architecture compared to turbomachines. Two rigid rotors (one light and one heavy) supported by two foil journal bearings were studied. Study is made in two different ways: by the analysis of the displacements spectrograms in two perpendicular directions on each bearing, or the study of the synchronous response at different unbalance masses. A comparison between experimental results and two theoretical models is made. Unbalance responses are compared to a linear rigid rotor model with 4 degrees of freedom, in which the dynamic coefficients of the foil journal bearings are obtained thanks to the Foil algorithm. Spectrograms show sub-synchronous vibrations that are computed thanks to a simplified dynamic force model. Experimental results show the limits in the foil journal bearings theoretical models. In order to improve knowledge and prediction of these components, it is now compulsory to establish a new non-linear dynamical model, enabling to predict both the synchronous unbalance responses and the complexity of the sub-synchronous dynamical signature of a rotor maintained by two foil journal bearings
Ercolanelli, Julien. "Étude numérique et expérimentale d'un système couplé stabilisateur et récupérateur d'énergie des vagues Experimental and numerical investigation of sloshing in anti-roll tank using effective gravity angle Experimental and numerical assessment of the performance of a new type passive anti-roll stabilisation system." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0008.
Повний текст джерелаGeps Techno's development is based on an innovative concept of a floating structure intended to produce electrical energy from several renewable marine energy sources, including wave power. The wave power system developed by Geps Techno is based on circulating water and creating a vortex within it. By taking advantage of the liquid hull phenomenon, the concept can also be used as a stabilization system for a ship or any other floating platform. The short-term objective of the company is the development of this technology allowing the stabilization and recovery of wave energy and for which there remain technological obstacles to be removed in order to achieve the viability and profitability of the system. To do this, in October 2015 Geps Techno launched the IHES (Integrated Harvesting Energy System) project, which consists of building a demonstrator of its wave power platform concept. The IHES project is one of the projects of the roadmap of the "Ecological ships" plan of New Industrial France. It is supported by Bpifrance within the framework of the Investments for the Future - Industrial Projects for the Future program. In order to master the objectives of stabilization and energy recovery, Geps Techno is studying the technological aspects necessary to switch from the energy available at wave level to that available at the wave turbine turbine. The Ph.D. thesis work supported by Fourestier in May 2017 focused on a first part "Definition and control of internal flows in the wave power system". Using CFD modeling, the latter resulted in operational models characterizing internal flows. This Cifre Ph.D. thesis follows on from Fourestier's work and deals with a second part "Modeling of the coupled platform / wave power system". All of this work should lead to an operational computer code correlated with experimental results making it possible to study the internal flow and the behavior of the float subjected to swell
Pagnoni, Filippo. "Design and Experimental Analysis of a Loop Heat Pipe for Thermal Control of Aircraft Engine Equipment." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2019. http://www.theses.fr/2019ESMA0004.
Повний текст джерелаIn this work, the development of a Loop Heat Pipe (LHP) for aircraft nacelle thermal management is presented. The study is focused on engine compartments and integrated equipment applications, according to the upcoming thermal management challenges in the next generation of engines. First, a feasibility study was performed, analyzing the thermal environment, the integration constraints and the identification of suitable working fluid construction material pairs. As for the latter aspect, water and DowthermTM J were identified as most suitable candidates with the lightweight aeronautical alloys considered for this environment. On one hand, the high triple point of water obliged to verify the wick mechanical resistance to repeated freezing cycles when soaked into pure water. On the other hand, compatibility tests were performed between DowthermTM J and the selected alloys, due to the lack of related data. In the former, the sintered titanium wick provided an excellent stiffness and it remained perfectly intact after more than 1500 cycles. In the latter, the thermal tests performed on parallel thermosyphon shave clearly shown the generation of non-condensable gases (NCG) inside all the samples starting from low operating temperatures. As a result, the compatibility of DowthermTM J was considered not fully satisfactory and this fluid was discarded. The next step concerned the design of the titanium/water LHP prototype. Robust numerical tools were developed for the final design validation: a simplified 0D nodal model for the entire device and a coupled 1D and 2D condenser model representation. The LHP prototype was manufactured and tested in different operating conditions. A significant amount of NCG was initially generated inside the device, due top assivation of the internal surfaces. Nonetheless, the experimental results demonstrated the LHP capability to satisfy the thermal requirements, even in presence of NCG, with standing high operating temperatures and pressures. Although the gas generation rate became negligible after several hours of tests, internal inspections performed at the end of the test revealed a deep alteration of the internal surface state, due to the chemical reactions with the working fluid. The results of this work represent an important milestone for the development of a LHP for aircraft nacelle applications. Essential information for the design of future generations of prototypes are provided, toward the validation and certification of LHP for nacelle thermal management
BEN, JEDIDIA ANIS. "Etude du comportement sismique d'un coeur de reacteur nucleaire de type r. E. P." Paris 6, 1993. http://www.theses.fr/1993PA066020.
Повний текст джерелаSarrot, Vincent. "Capture de fines particules par des inclusions fluides." Toulouse, INSA, 2006. http://eprint.insa-toulouse.fr/archive/00000189/.
Повний текст джерелаThis study focuses on the collision mechanism between a spherical bubble and particles when the particle diameter remains less than some percents of the bubble diameter. This situation corresponds to the first step of the particle capture in flotation processes. The efficiency determination is based on experimental measurements and Direct Numerical Simulations (DNS). Experimentally, a single bubble flotation cell has been build for the purpose of measuring capture efficiency. Small spherical bubbles are created by a capillary tube and then arise through a suspension capturing glass particles. Captured particles are recovered by overflow and are counted in a particle counter. Results are analysed and the magnitude is favorably compared to those of Ralston et al. (1999a). Efficiencies exhibit a general decreasing trend with particle to bubble diameters ratio dp/db, in opposition to the trend analytically predicted by collision efficiency models in litterature. This effect seems to be due to wetting properties of particles. Numerically, the flow around the bubbles is computed and particle trajectories determined. Particle with Stokes number less than 1 follow the streamlines. In this case, the collision efficiency only depends on the shape of the streamlines and on the size of the particles. Numerical simulations have been performed over large parameter ranges (particle to bubble diameters ratio, Reynolds number of the bubble and the degree of contamination of the bubble surface). The collision efficiency is found to increase with the Reynolds number and significantly decrease with the level of contamination. For clean (respectively fully contaminated) spherical bubbles, the efficiency evolves as dp/db (respectively (dp/db)2), whatever the bubble Reynolds number and the particle size. For partially contaminated bubbles, efficiency can be scaled with dp/db or (dp/db)2 depending on both the level of contamination and the particle size. Correlations of the numerical results are proposed for efficiencies versus dp/db, bubble Reynolds number and interface contamination degree
Al, Galib Dhafar. "Comportement statique et dynamique de structures fusibles susceptibles d'absorber les énergies d'impact en cas de crash." Lyon, INSA, 2003. http://www.theses.fr/2003ISAL0033.
Повний текст джерелаThe objective of this study is to contribute to the improvement of the behavior to the crushing tubular extrusion, which should permit to find a structure optimizing the absorption of impact energy. An attempt to identify the characteristic behaviors of the studied structures was made by an experimental, analytical and numerical approach, Three main objectives constitute the frame of our study: * How will be able to reduce, during the crash, the first peak load, which reflect the decelerations transmitted to the occupants of the vehicle? * How will be able to dissipate by a controlled manner the kinetic energy during crash event? The proposed process, which reduced the first load peak, can be used for other geometries and other materials? * How can one evaluate the influence of the rupture of aluminum alloy on the global behavior of tubes, and what criteria can one propose to detect the rupture? On the experimental and numerical plan, the behaviors of static and dynamic crushing of circular and square aluminum tubes have been studied. A process that permits to decrease the deceleration transmitted to the passengers during impact or frontal collision has been proposed and validate. We could also have evaluated the behavior of these tubes while varying the mass and the speed of impactor and finally to study geometric imperfection, boundary conditions and loading affects on the static and dynamic behavior. Propositions are made for the choice of the geometric parameter used in order to facilitate the similarity (material, geometry). Finally, we linger especially on the influence of the rupture, that it is necessary to consider in an objective of design and quantification of the energy absorbed
Nottet, Romain. "Contribution au développement d'un moyen de mesure simultanée des vitesses et températures adapté aux essais incendie in situ." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0199/document.
Повний текст джерелаFire smoke spread prediction is a main issue in building fire safety studies. Safety devices can be tested thanks to in situ experiments, high lighting potential dysfonction. The smoke spread velocity is then a significant measurement. Hostile environment induced by fire attack sensors and can quickly damaged them. Hence, we need reliable, high temperature proof and cheap probe. The current fluid mechanics measurement techniques are not appropriate to real scale test with uncontroled conditions. Improvement in signal processing permit developpement of CCV technique (Cross correlation velocimetry). This apporach is based on frozen eddies Taylor hypothesis. For our concerne, the cross correlation calculated from the signal of two ε-distant thermocouples introduced in turbulent flow. The aim of the signal processing is to find temperature information from one thermocouple to the other one. Then, the delay obtained by cross correlation gives the velocity of the flow. Our objetcives is to adapt this laboratory technique to in situ measurements. Thermocouples are non intrusives, cheap and calibration-less responding to our need. At first, operating optimal conditions and limits are defined comparing laboratory-scale CCV measurements with classical techniques. Then, the quality of this technique is assessed in real conditions which high light the main adaptability difficulties
Limouni, Achour. "Étude dynamique, théorique et expérimentale des essais de frottement pion-disque." Compiègne, 1998. http://www.theses.fr/1998COMP1106.
Повний текст джерелаPélissier, Jean-Luc. "Automatisation d'une station de test par faisceau d'électrons : localisation dynamique de fautes." Montpellier 2, 1987. http://www.theses.fr/1987MON20269.
Повний текст джерелаMaganga, Fabrice. "Caractérisation numérique et expérimentale des effets d'interaction entre une hydrolienne et le milieu marin." Le Havre, 2011. http://www.theses.fr/2011LEHA0019.
Повний текст джерелаThis work aims to characterise by the means of experimental and numerical modeling, the behavior of marine current turbine and the characteristics of the wake generated under realistic inflow conditions. For that purpose, we used a tribladed horizontal axis turbine of 0. 7 m of diameter. Particular attention is paid to the flow characteristic effects on the efficiency of the turbine, but also on the generated wake. Tests are carried out in the Ifremer wave and current flume tank in Boulogne sur Mer and in the towing tank of Brest, taking into account current profils, upstream turbulence intensity level and disturbances generated by wave/current interaction. The development of a threedimensional software based on vortex methods, taking into account the non stationary evolution of the wake generated by a turbine is implemented. The obtained numerical results are compared to the experimental ones, making the validation of tools possible in terms of efficiency and of wake evolution
Sajet, Philippe. "Processus d'intéraction attrition/rhéologie lors du transport hydraulique d'une suspension de nodules concassés dans un fluide porteur." Compiègne, 1989. http://www.theses.fr/1989COMPD188.
Повний текст джерелаThomas, Michel. "Transport de l'eau à travers une membrane perfluorosulfonique Nafion : relations avec la microstructure : développement de membranes composites à haute perméabilité aux gaz." Lyon 1, 1989. http://www.theses.fr/1989LYO10174.
Повний текст джерелаSpiazzi, Edgardo Américo. "Conception et mise au point d'un générateur de régimes instationnaires d'écoulement : application au problème du colmatage des membranes d'ultrafiltration et de microfiltration." Lyon 1, 1991. http://www.theses.fr/1991LYO10074.
Повний текст джерелаLongchamp, Quentin. "Analyse expérimentale et numérique de l'écoulement dans le canal d'entrée d'un modèle de turbine bulbe." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30591/30591.pdf.
Повний текст джерелаThis work is part of the research activities of the Hydraulic Machines Laboratory of the Laval University and its objective is to contribute to the characterisation of the intake flow in a model of a bulb turbine. The representation of the mean velocity fields and the turbulent fluctuations under predefined operating conditions were obtained by the use of a LDV measurement system. Mass-flow imbalance and vortices in the intake channel were identified. The conception of an obstacle geometry causing a non-uniformity in the intake channel has been developed taking in consideration the predictions of numerical simulation. Numerical simulations of the complete machine for both steady and unsteady case were performed with and without obstacle in the intake channel. The objective of this process was to evaluate the influence of the intake flow condition on the turbine performances. Moreover, comparisons between experimental and numerical quantities were made.
Coulaud, Maxime. "Conception d'un banc de calibration pour l'étalonnage de capteurs de frottement pariétal." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30153/30153.pdf.
Повний текст джерелаThis Master’s thesis presents the design of a hydraulic tunnel. The bench should allow calibrating wall shear stress hot-film probes easily and rapidly. During this project, 3D CFD simulations have been performed to find minimum aspect ratio and minimum length of development to reach 2D fully developed flow. Then, mechanical and hydraulic analyses have been carried out to determine if the design conforms to specifications. After manufacturing, velocity and pressure measurements have been performed respectively with a LDV system and differential pressure sensor. By comparing different velocity profiles, it has been confirmed that the flow in test section is 2D fully developed. However, some discrepancies with the literature and the CFD simulations have been detected. The study of some parameters allowed to determine possible causes for these differences and to propose future studies to improve wall shear stress estimation.
Besnard, Gilles. "Caractérisation et quantification de surfaces par stéréocorrélation pour des essais mécaniques du quasi statique à la dynamique ultra-rapide." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2010. http://tel.archives-ouvertes.fr/tel-00579260.
Повний текст джерелаHamidipour, Mohsen. "Plugging phenomena in trickle bed reactors - Understanding the Mechanisms and Investigating Novel Mitigation Strategies." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27287/27287.pdf.
Повний текст джерелаBarrande, Maud. "Caractérisation de matériaux poreux pour la séparation de protéines." Aix-Marseille 1, 2007. http://www.theses.fr/2007AIX11050.
Повний текст джерелаRomero, Figueroa Julio. "Etude des transferts sur des systèmes à membrane non-conventionnels : cas du procédé d'évaporation osmotique et de la perméation de fluides supercritiques." Montpellier 2, 2002. http://www.theses.fr/2002MON20135.
Повний текст джерелаKhallaki, Kaoutar. "Analyse numérique des mécaniques d'intensification du transfert thermique par promoteurs de tourbillons dans les échangeurs à tubes ailetés." Valenciennes, 2006. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/a058154b-2a0c-4692-a6e8-df40778d3325.
Повний текст джерелаThis work is related to the heat transfer enhancement in compact finned tube heat exchangers. We study numerically the flow topology and its influence on heat transfer. The effects of fin spacing and velocity inlet variation are examined. Results are compared and validate with dynamic and thermal experimental measurements. This study shows that the flow in finned tube heat exchangers is characterised by the presence of horseshoe vortices in front of the tubes. These vortices increase the heat exchange and interact with a the dead zone located at the downstream of the tubes which is a region of a low heat transfer. Then, we propose an innovative technique of heat transfer intensification in continuous fin and tube heat exchangers by inserting vortex generators on fins
Si-Hassen, Djaffar. "Identification et caractérisation des mécanismes de colmatage et de décolmatage d'une membrane de microfiltration et application à l'analyse de l'hystérésis du flux de filtrat." Compiègne, 1997. http://www.theses.fr/1997COMP1037.
Повний текст джерелаSais, Hassiba. "Étude de l'effet du débit pulsé en microfiltration et ultrafiltration sur membranes organiques à fibres creuses." Compiègne, 1995. http://www.theses.fr/1995COMPD858.
Повний текст джерелаAgrapart, Quentin. "Bilan d’énergie au contact et contribution de la thermomécanique sur la dynamique d’interaction aube - revêtement abradable de turboréacteur aéronautique." Thesis, Lille, 2018. http://www.theses.fr/2018LIL1I033.
Повний текст джерелаThis thesis adresses the industrial problem of blade-tip / abradable coating interaction in aircraft engine leading to divergent dynamic response of blades. Even if it is well known that the dynamic behavior of the structure plays a key role on the divergence, wear and heating seem necessary to amplify vibratory motion leading to blade damage. In this multi-physic context the aim of this work is to provide explanations on the origins of the divergence by introducing thermomechanical phenomena. The work is divided in 2 parts. First, an energy balance at the rubbing contact is established through experimental analysis of interactions on a simplified test rig, coupled with inverse simulation models for heat flows estimation. The proposed method highlights different energy partitions between the blade and the abradable coating depending of the activation of different wear mechanisms. On the other hand, a thermomecanical strategy is developed for the simulation of blade-abradable rubbing events taking account of specific issues : different time scales between thermal and mechanical phenomena, generation and partition of heat flows at the interface, contact resolution, wear effects, thermal expansion and complex boundary conditions. Several divergent cases are investigated on the basis of comparison with experimental results available on compressor. It is shown that thermomechanical effects are sometimes overriding or conversely relegated to a more distant role, depending on the initial conditions of interaction. The competition of phenomena acting upon contact (thermal expansions, wear, etc.) is clearly demonstrated and certain aspects remain open to perspectives
Bouhelassa, Mohammed. "Optimisation du transfert d'oxygène dans un bioréacteur Emulsair." Compiègne, 1985. http://www.theses.fr/1985COMPI189.
Повний текст джерелаRjimati, El Arbi. "Microfiltration tangentielle de suspensions particulaires : modélisation." Montpellier 2, 1990. http://www.theses.fr/1990MON20029.
Повний текст джерелаSalemi, Bamdad. "Contributions expérimentales sur les écoulements diphasiques dans un évaporateur de climatisation : essais en eau-air et en réfrigérant R134a." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0282/document.
Повний текст джерелаUnderstanding of multiphase flows in mini-channel evaporators is essential for the performance of air-conditioning systems, particularly in automotive sector. This thesis is mainly interested in behavior of inlet flow and phase distribution in the mini-channels. Initially, an adiabatic two-phase flow at the evaporator's inlet was studied. A transparent experimental apparatus with the same geometry as an evaporator's inlet has been designed. This test section helped us to reproduce the same flow regimes with air-water as flow regimes encountered with R134a in an evaporator. Several characterization techniques were used (visualization, conductance probes, Pitot tube and pressure taps) to determine pressure losses, liquid film thickness and gas velocity in a predominantly annular flow regime. Following the same principle, another experimental facility in stainless steel was developed to directly characterize the R134a flow at the evaporator's inlet. Finally, we have extended the study to the case of a compact evaporator in two adiabatic situations: single-phase (water) and two-phase (air-water). Pressure losses, phase distribution along the evaporator and flow regime in mini-channels were studied on an evaporator made of transparent materials (polycarbonate) with a close geometry to that of a real evaporator. Numerous results were obtained to provide a consistent database that would be useful for numerical simulation of this type of two-phase flows
Sarrade, Stéphane. "Etude du couplage de l'extraction par CO2 supercritique avec la séparation par membrane de nanofiltration." Montpellier 2, 1994. http://www.theses.fr/1994MON20259.
Повний текст джерелаEl, Itawi Hassan. "Crossing of a liquid-liquid interface by a droplet under centrifugal effect for a micro-encapsulation process." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0039.
Повний текст джерелаThe applications concerned by microencapsulation are constantly growing and cover sectors of industrial activities as varied as agriculture, pharmacy, food industry and even cosmetics. This work is a part of the development of a microencapsulation process based on sub-millimeter-sized drops crossing a liquid-liquid (L-L) interface under the influence of an external force, in this case centrifugal force. The objective of this work is to understand the hydrodynamics and interface mechanisms before, during and after the passage of a drop through a L-L interface, and leading to its coating. For this purpose, numerical and experimental approaches have been combined and complemented by theoretical models. A numerical method solves the Navier-Stokes equations for this three-phase flow by a finite volume discretization combined with the Level-Set and ghost-fluid methods to capture the interface dynamics and to deal with the discontinuities at the interfaces; it allows to compute the velocity field around the deformable droplets during the interface crossing. An experimental device for forming aqueous drops of sizes (100-1400 μm) and forcing their passage through a L-L interface using a centrifugal force of magnitude up to ≈ 2500g was designed to observe all stages of the process by a high-speed camera synchronized with the rotation of the encapsulation cell, and to analyze the crossing conditions and the different fluid entrainment regimes. The crossing or the rebound of a droplet at the interface is a result of the competition between interfacial forces, the weight of the drop and its inertial force, and is due to complex phenomena involving non-dimensional numbers. The two approaches made it possible to define the crossing conditions as a function of the relevant non-dimensional numbers: ξ12ξ13 and Bo13, and to develop a scaling law of the maximum length of the column formed during crossing, and the resulting drop coating volume. This work has thus made it possible to determine the optimal conditions, on the scale of a single drop, to encapsulate a liquid droplet by using this process, a necessary step prior to the design of an industrial pilot operating at a continuous production rate
Voeltzel, Nicolas. "Molecular simulation of an ionic liquid as lubricant : From bulk rheology to nanoconfinement." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI119.
Повний текст джерелаIncreasing economic and environmental constraints tend to reduce the amount of lubricant used in mechanical systems. This results in nanometric film thicknesses in the contact areas, leaving only a few layers of lubricant molecules to ensure the separation of the surfaces. To meet this challenge, new fluids are being considered such as ionic liquids which feature a great potential as lubricants. Through Molecular Dynamics simulations, the rheological response of an ionic liquid to different conditions of temperature, shear and pressure is first characterized in detail. The ability of the ionic liquid to lubricate thin films is confirmed. Besides, this study goes back over the classic analytical models used in rheology. The ionic liquid is then nanoconfined between two representative surfaces of a steel-steel contact. The combined effects of wall slip, shear-thinning and temperature rise provide answers to explain the saturation of the shear stress. Finally, the influence of different low friction surface coatings is analyzed. According to the material used, very different dynamical behaviors occur. Moreover, it is shown that the use of polar surfaces significantly impacts the response of ionic liquid lubricated contacts
Ikhennicheu, Maria. "Étude expérimentale de la turbulence dans les zones à forts courants et de son impact sur les hydroliennes." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I055/document.
Повний текст джерелаFrench waters have a strong potential for tidal turbines applications. In these areas of strong currents, intense velocity fluctuations are observed in the water column. They ultimately come from variations in seabed bathymetry and can have a strong impact on tidal turbine energy production and fatigue. In order to understand the turbulent structures generation in the wake of obstacles and to build a data base for future numerical studies, the Alderney Race conditions are reproduced experimentally, in a wave and current tank, in Froude similitude and with a Reynolds number as high as possible. In this study, real bathymetric variations are represented using canonical elements: a cube, a cylinder, an inclined plane or a combination of all three. Cases with bathymetric variations higher than average (obstacle alone) are differentiated from average rugosity cases (obstacles combined). In order to characterize the wake behind these obstacles and to study how turbulence evolve in the water column, PIV and LDV measurements are made for various turbulence rates of the incoming flow. Results show that the cylinder alone produces the most spread out wake. In that case, large scale turbulent structures, rising all the way to the surface, are identified. The development of processing methods and data analysis allows the detection of vortex centres and the determination of their properties. The cylinder wake impact on a tri-bladed horizontal axis turbine behaviour is then studied. Depending on the position of the turbine relative to the obstacle, the turbine can be subject to large amplitude loads due to velocity fluctuations generated by the presence of the obstacle in the flow. Force measurements on the blades and turbine dynamic behaviour characterization allow to quantify those load variations. They depend on the turbulent structures impacting the turbine and the shear in the velocity profile. The results obtained could be exploited for further fatigue analyses on blades or on other tidal turbine components
Dijoux, Alexandre. "Influence du fluide du travail, de la technologie des échangeurs et du pilotage dynamique d’un cycle ORC sur l’intérêt et les performances d’un système de conversion d’Énergie Thermique des Mers." Thesis, La Réunion, 2020. http://www.theses.fr/2020LARE0036.
Повний текст джерелаThe temperature difference between the hot surface seawater (of tropical solar origin) and the cold one at depth (which comes from the poles) constitutes a stable, environmentally-friendly and renewable source of energy available in the ocean. This ocean thermal energy conversion (OTEC) can be used to produce electricity by the way of an organic Rankine cycle (ORC). However, the small temperature difference between hot and cold sources represents a technical challenge both for heat transfers and for cycle performances. The objective of this thesis is then to explore the operation improvement possibilities of an ORC applied to OTEC, to complete the knowledge of the system components and to highlight the advantages of this new technology on a non-connected grid such as that of Reunion Island. This work is based both on simulations and on experimental results obtained on a 450 kW thermal energy onshore prototype named PAT ETM. In the first chapter, a new method for the choice of the working fluid is proposed. The study brings out some fluids so far little considered for OTEC. In the second chapter, the experimental tool (the PAT ETM) is presented extensively. The third chapter reports the heat exchanger technologies that have been tested and characterized. The fourth chapter deals with the dynamic modeling of an OTEC system. This study leads to the assessment of the control-lability of a complete power plant and shows a still little explored opportunity: that of using OTEC as a management tool to control an electrical network
Nicolas, François. "Reconstruction de champs instantanés de masse volumique par BOS 3D. Applications à l’étude d’écoulements complexes en grande soufflerie." Thesis, Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0003/document.
Повний текст джерелаThis PhD work is part of the development of advanced metrological tools for fluid dynamics, especially for wind tunnel applications. 3D Background Oriented Schlieren (BOS), which has been developed at ONERA, is a line-of-sight technique which takes advantage of light rays deviation through an inhomogenous index media to measure density. It consisted in comparing a reference image of a textured background with the image of the background with the flow in presence. Image correlation can then be used to compute light rays deviations. Performing such acquisition from multiple view points, allows to reconstruct the corresponding density field, by solving an inverse problem. In order to pursue the technique development, we first elaborate a systematic processing chain and improved the robustness of the reconstruction algorithm. After validating our method on synthetic data, we applied it on a 3DBOS bench equipped with 12 cameras. Thereafter, the technique has been set up for the first time in a wind tunnel environment, on a subsonic hot jet configuration. During this test campaign, the technique has been validated via thermocouples measurements.Moreover, 3DBOS and stereo-PIV coupled acquisitions have been performed. Thereafter, a demonstration in industrial wind tunnel has been performed in ONERA S1MA facility. Compressible flows issues encountered during those tests lead us to finer analysis high density gradient flows. A 3DBOS test bench has been built in laboratory in order to optimize underexpanded jet measurements. On this specific configuration, very good agreements have bee obtained in comparison with literature and with a DES simulation. This study has allowed the extension of 3DBOS application domain to compressible flows and it has demonstrated its use in a wind tunnel environment. The quality of the results highlights the technique potential for flows physical investigation
Wisniewski, Christelle. "Etude du comportement de cultures mixtes en bioréacteur à membrane. Cinétiques réactionnelles et filtrabilité." Montpellier 2, 1996. http://www.theses.fr/1996MON20005.
Повний текст джерелаBlanpain-Avet, Pascal. "Étude des paramètres gouvernant l’effet du backpulse et de la superposition de pulsations de débit et de pression lors de la microfiltration du jus de pomme sur membranes minérales." Compiègne, 1991. http://www.theses.fr/1991COMPD360.
Повний текст джерелаTaillefer, Edith. "Méthodes d'optimisation d'ordre zéro avec mémoire en grande dimension : application à la compensation des aubes de compresseurs et de turbines." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/205/.
Повний текст джерелаThis thesis presents the result of collaboration between Snecma and IMT (Institut de Mathématiques de Toulouse). New efficient optimisation methods have been developed in IMT and then applied on blade design at Technical Department of Snecma. In many industrial applications, the gradient of a cost function is not available and if it is available, its domain of validity is very restricted. This led to the recent development of numerous zero order optimisation methods. Two numerical tools for large dimension optimisation without derivative computation are discussed here. The main idea is to use the cost function evaluations, which are performed during the optimisation process, to build a surrogate model. Addition of a new point during the optimisation process must reach a double target: progress towards the optimum and improve the approximation of the cost function for the next step. Among all approximation techniques, we focus here on those which catch easily constant behaviour. As a matter of fact, other methods introduce false local minima. Consequently we focus on two methods: neural networks and sparse grids. Especially sparse grid is a new promising way for various scientific topics thanks to its adaptative and hierarchical properties. Efficiency of these methods is proved on analytical functions and confirmed on industrial cases and especially for bend momentum balance of compressor and turbine blades
Ecault, Romain. "Etude expérimentale et numérique du comportement dynamique de composites aéronautiques sous choc laser. Optimisation du test d'adhérence par ondes de choc sur les assemblages composites collés." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2013. http://www.theses.fr/2013ESMA0031/document.
Повний текст джерелаThis work aims the development of a non-destructive technique to control the mechanical quality ofaeronautics adhesive bonds (ENCOMB project). Shocks were realized by use of laser sources or gas gun, anddifferent techniques were used to analyse the shocks such as: VISAR, PDV, Shadowgraphy, optical andconfocal microscopy, X-ray radiography, ultrasound testing…Epoxy resins and carbon/epoxy compositelaminates were first investigated. Monitored laser shocks, in addition to post-mortem analyses, enabled tobetter understand the shock phenomenon on these complex materials. The results obtained on bondedcomposite showed that the laser shock technique can be used to discriminate different adherence levels.The use of numerical models, developed thanks to the experimental data, enabled to analyze the shockpropagation in these complex assemblies. They also evidenced the need for optimization, in order to testonly the bond interface and not to break the composite parts on the assembly. Several optimizationsolutions are formulated such as the use of tuneable pulse duration, or double shock configurations. Someof these solutions have been experimentally validated, and the numerical optimization gives the shockparameters to use for the next experimental campaigns. Finally, this work provides original results on thedynamic behaviour of composite materials under laser shock and leads to the adaptation of the laser shockadhesion test to any kind of bonded composite assemblies
Mandard, Romain Baptiste. "Dynamique de contact aube- revêtement abradable : identification expérimentale de la force et des mécanismes d'interaction." Thesis, Ecole centrale de Lille, 2015. http://www.theses.fr/2015ECLI0001.
Повний текст джерелаMinimizing the clearance between turbofan blades and the surrounding casing is a key factor to re-ducing leakage flows and consequently improving efficiency. The tight clearance may lead to blade-casing interactions. An abradable coating is deposited on the casing to accommodate blade incursions and thus to protect the blades and the casing from severe damage. Blade/abradable-coating interactions involve tribological and vibratory phenomena at high velocity and temperature. Experimental knowledge of these interactions is paramount to the proper design of abradable materials and the prediction of their lifetimes through numerical simulations. The purpose of this thesis is to identify experimentally the force and the mechanisms occuring during interaction between a vibrating blade and an AlSi-Polyester abradable coating. To this end, experiments were conducted on a dedicated test rig, in conditions representative of low-pressure compressor situation. Specific methods involving dynamical measurements and analytical models have been developed in order to obtain the blade/abradable-coating interacting force as well as the blade tip incursion. The influence of temperature, coating nature and blade stiffness has been studied. The interaction mechanisms and wear of the abradable coating have been investigated and correlated with the interaction conditions. This work was achieved within the framework of cooperation between Laboratoire de Mécanique de Lille (France), SAFRAN-SNECMA (France) and ONERA, the French Aerospace Lab
Houarche, Nicolas. "Modélisation de défauts paramétriques en vue de tests statiques et dynamiques." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2009. http://tel.archives-ouvertes.fr/tel-00481534.
Повний текст джерелаBaïz, Sarah. "Etude expérimentale du contact aube/abradable : contribution à la caractérisation mécanique des matériaux abradables et de leur interaction dynamique sur banc rotatif avec une aube." Phd thesis, Ecole Centrale de Lille, 2011. http://tel.archives-ouvertes.fr/tel-00605091.
Повний текст джерелаBreil, Pascal. "Drainage des eaux claires parasites par les réseaux sanitaires ; mécanismes et approche quantitative." Montpellier 2, 1990. http://www.theses.fr/1990MON20103.
Повний текст джерелаBoujlel, Jalila. "Déplacement d’un objet à travers un fluide à seuil : couche limite, contrainte seuil et mouillage." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1114/document.
Повний текст джерелаThe behavior (flow, adhesion,...) of a yield stress fluid along a solid surface is a recurrent problem in many industrial processes. The non-Newtonian character of this type of material makes it difficult to apply the concepts established in the case of similar flows of simple liquids. In this thesis, we study this problem experimentally by analyzing the flow generated along a solid plate moving vertically (penetration and withdrawal) through a simple yield stress fluid. We first determine the relationship between the measured force along the object and the rheological properties of the material. We derive a new technique for measuring the yield stress of the material. We describe then the local characteristics of the flow generated during the penetration of the plate. We show that the flow is located around the object in a layer of uniform thickness, while the rest of the fluid is deformed but remains in its solid state. We describe the process by which the boundary layer develops and determine the distribution of solid / liquid zones around the object. Finally, we study the effects of wetting and adhesion on the plate. In particular, we present an experimental approach to evaluate the surface tension of a yield stress fluid
Cherdieu, Patrick. "Contrôle du décollement dans un diffuseur aubé de turbomachine centrifuge." Thesis, Ecole centrale de Lille, 2013. http://www.theses.fr/2013ECLI0020/document.
Повний текст джерелаThe performance improvement of turbomachinery operating at off-design conditions can be achieved by the understanding of unsteady phenomena which are occuring in its components. The present study is focussing on the interaction between a centrifugal impeller fan and its vaned diffuser. It aims at analysing precisely these unsteady phenomena (and especially the fluctuating separated region identified on the vanes wall) and their consequences on the diffuser performance by three holes probe and unsteady pressure measurements. In a second step, devices for a passive control of the separation are introduced. Several configurations are tested and their results are compared
Porras, Vazquez Alejandro. "A molecular approach to the ultimate friction response of confined fluids." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI087.
Повний текст джерелаIn order to control energy losses in mechanical systems, a thin film of lubricant is often introduced between the solids in contact. The lubricated point contacts operate in the elastohydrodynamic regime, characterized by high pressures (of the order of GPa) and thin film thicknesses (of the order of 100 nanometers). At high shear rates, the fluid may exhibit a limiting shear stress whose physical origin is still uncertain. At present, the empirical models available for the prediction of friction fail to describe the ultimate response of lubricants at these severe operating conditions. In addition, in-situ experimental analysis is very difficult to achieve due to confinement and high pressures. Thus, in this thesis, the problem is approached from the angle of modeling at the atomic scale. The shear behavior of three fluids (a traction fluid, a model lubricant and an industrial lubricant for the aerospace industry) is analyzed by Molecular Dynamics Simulation. The numerical results are then compared qualitatively and quantitatively with experimental tests. The friction response is independent of the velocity profile in the confinement thickness, the latter appearing rather as a consequence of boundary conditions at the surfaces. The limiting friction regime naturally occurs when the lubricant is subjected to thermodynamic conditions characteristic of a solid state. In this case, the dynamics of the molecules is strongly slowed down. The activation energy increases rapidly with the pressure, so that the diffusion becomes negligible at high pressure, even at the severe shear rates imposed in the Molecular Dynamics simulations. The macroscopic response to this phenomenon is thus a saturation of the value of friction. This work ends by laying the foundations of a modeling that will allow the prediction of lubricated friction under severe conditions
Sévénié, Benjamin. "Capsule deformation in a microfluidic channel : experiments, characterization and Proper Orthogonal Decomposition." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2278/document.
Повний текст джерелаThe motion and deformation of a liquid-filled classic microcapsule flowing in microchannels is investigated bath experimentally and numerically. The flow of capsules into a straight microfluidic channel with a square cross-section is firstly studied. The objective is to develop a method to determine the mechanical properties of the capsule membrane from its hydrodynamic deformation. A method of identification has been devised to compare the particle deformed shape measured experimentally in the microchannels to the ones predicted by a three-dimensional numerical model for the same configuration. The precision and robustness of the inverse analysis algorithm have been tested when the microfluidic channels slightly depart from pure squareness. We have finally applied the method on microcapsules with a membrane made of reticulated albumin and determined their rnechanical properties. A Proper Orthogonal Decomposition (POD) has then been applied to the shapes assumed by the capsules while flowing in either a straight or bi furcated channel. Using numerical data in a straight channel, we have determined the dimension of the capsule shape variety. We have then interpolated the coefficients resulting from the POD analysis to compute the capsule deformed shape at any time for any flow parameter. Capsules have finally been investigated flowing in a bifurcated microchannel. Qualitative results of the motion and deformation of capsules in such channel have been obtained. A semi-automatic contour detection program has been developed to improve the image analysis. The POD method has been applied to the experimental results, thus proving the feasibility of building a reduced-order model of the phenomenon by using a POD reduced basis
Phalippou, Pierre. "Data-enabled, reduced-order simulation of dynamical systems with application to vehicle crash simulation." Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2544.
Повний текст джерелаVehicle manufacturers face numerous constraints regarding security, comfort, weight, and fuel consumption when designing new automotive vehicles. Numerical simulation, and more precisely, the finite element method, is extensively used in the process to achieve cost reduction while allowing to test the impact of multiple design parameters on the system behavior. Nevertheless, industrial finite element models of automotive crash are growing prohibitively expensive in computation time, slowing down the design process. Numerous model order reduction methods have been developed in order to speed-up simulations by making use of the humongous amount of collected data and the repetitiveness of computations with slight changes to the design variables. This thesis aims to apply model order reduction methods to finite element simulations of automotive crash, involving material and geometric nonlinearity as well as contact. This project, conducted in close collaboration between the car manufacturer PSA group, the software developer Altair engineering, and the computational mechanics group at the UTC-CNRS joint laboratory Roberval, targets intrusive methods necessitating modifications in the finite element solver source code. Amongst different promising methods reviewed in the state-of-the-art, our work focuses on projection-based reduced order modeling and hyper-reduction. A reduced-basis of global shape functions is built upon relevant data in the online training phase and used online to reduce the model size, enabling the hyper-reduction of internal forces and computational speed-up. The contributions of this thesis concern three aspects of the training phase. Developments of the incremental singular value decomposition allow for a more flexible and faster reduced-basis training. The proposed sparse criterion enables the formation of basis functions subsets with enhanced performances and better correlation between the online training phase approximation error and the actual error in the online reduction phase. An innovative formulation of the hyper-reduction optimization problem involving mixed-integer programming, added constraints on polynomial integration, and volume conservation is suggested for the benchmarking of future heuristic methods. All implementations are performed in the industrial explicit finite element solver Altair Radioss with complete access to the source code. To the author's best knowledge, the implementation of such a method in industrial explicit finite element solver represents a significant differentiator of the present contribution. Implementation specific difficulties relevant to this aspect of the thesis are discussed. Finally, recommendations, as well as perspectives and further developments required for the robust application of the method to industrial numerical simulations of vehicle crash, are given
Hu, Xu-Qu. "Mouvement et déformation de capsules circulant dans des canaux microfluidiques." Phd thesis, Université de Technologie de Compiègne, 2013. http://tel.archives-ouvertes.fr/tel-00857260.
Повний текст джерелаMichaïe, Sandra. "Experimental study of the fundamental phenomena involved in pool boiling at low pressure." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI040/document.
Повний текст джерелаBoiling is an efficient heat transfer mode used in numerous thermal or energy systems. In some systems boiling takes place at low pressure. The static head of the liquid column over the wall where bubbles nucleate is then not negligible against the saturation pressure at the free surface level. The pressure and the induced subcooling degree therefore cannot be considered as homogeneous around growing bubbles, resulting in non-homogeneous thermophysical properties in the fluid. The relative influence of the forces acting on a growing bubble differs from higher pressure conditions, yielding specific bubble dynamics features. Heat transfer is consequently also affected. The effect of the pressure on pool boiling was experimentally investigated during the isolated bubbles regime taking place from a single activated nucleation site. Experiments were first conducted with water for a wide range of subatmospheric pressures. Four distinct bubble dynamics behaviors were identified through high-speed camera visualizations. An adapted image processing of the recordings enabled the measurement of several bubble dynamics characteristics. In order to generalize the concept of pool boiling at "low pressure" and to get a better understanding of the related fundamental phenomena, new experiments were performed with a second fluid, cyclohexane, chosen from original thermodynamic similarity with water boiling at pressures lower than atmospheric. The comparison of fluids’ behaviors made possible the identification of parameters governing the specific phenomena occurring during boiling at low pressure. Besides, the experimental facility was improved to provide new functionalities. The high-speed measurement of the heat flux transferred under the growing bubble, its synchronization with the high-speed videos images and the study of boiling on enhanced surfaces are in particular made possible. Results are encouraging for a better understanding of the specific behaviors of low pressure boiling and for its future implementation in practical applications