Dissertationen zum Thema „Simulation aux grandes échelles de tourbillons“
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Moldoveanu, Cristian-Emil. „Simulation aux Grandes Échelles de tourbillons longitudinaux soumis à une turbulence extérieure intense“. Toulouse, INPT, 2007. http://ethesis.inp-toulouse.fr/archive/00000696/.
Der volle Inhalt der QuelleThe aim of this thesis is to study the behavior of the vortices under the influence of an external turbulence. We present the main mechanisms of instability, which is the basis of the counter-rotating vortices longitudinal decay. For the simulations we have selected the software JADIM developed by IMFT, adapted for Large Eddy Simulation of the turbulent flows. The validation of the numerical methods and of the software used, is made by comparing the theoretical and the numerical results of a single longitudinal vortex flow, in absence of external disturbances. We studied the behavior of a perturbed flow to the interior or to the exterior of a vortex. The study of the effect of the external turbulence on a counter-rotating longitudinal vortices pair highlighted the competition between elliptical and Crow instability. The simulation of the vortices pair in ground effect highlighted the generation mechanism of a vorticity layer and the generation of the secondary vortices
Bénard, Pierre. „Analyse et amélioration d'une chambre de combustion centimétrique par simulations aux grandes échelles“. Thesis, Rouen, INSA, 2015. http://www.theses.fr/2015ISAM0018/document.
Der volle Inhalt der QuelleDesigning a meso-scale combustion system remains a challenging scientific and technological issue. Increasing the surface-to-volume ratio promotes wall heat losses, reduces the residence time and turbulence intensity. The main objective of this thesis is to understand the physical phenomena involved in the centimetre-sized asymmetric whirl cubic burner of 8 x 10 x 8 mm3 (millimètre cube) and develop specific adapted numerical tools. The methane/air reactive flow is studied using detailed LES. While fuel and air are injected separately, combustion takes place in the premixed regime. However combustion is far from being complete, causing low combustion efficiency and significant emissions of pollutants. The second objective is to adapt in the best possible way the performances of this burner. Hydrogen enrichment of the fuel mixture showed significant efficiency enhancement and reduced pollutant emissions. Several other combustor geometries are also studied, paving the way for future improvement
Grébert, Arnaud. „Simulation numérique aux grandes échelles du contrôle de l'interaction onde de choc/couche limite au moyen de micro-générateurs de vortex“. Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0046.
Der volle Inhalt der QuelleBecause it is ubiquitous in high Mach number internal and external flow of interest in aeronauticalapplications, shock wave/turbulent boundary layer interaction (SBLI) is characterised by alow-frequency unsteadiness which generates large wall-pressure fluctuations that can occur at theresonant frequency of the structures. This work is devoted to the study of passive flow controldevices such as microramp vortex generators (mVGs) to alleviate these detrimental effects of SBLI.Large-eddy simulations (LES) have been performed based on an experimental configurationby Wang et al. (2012) of a SBLI under the influence of microramps at a Mach number ofM = 2.7 and a Reynolds number of Re× = 3600. The use of microramps has been shown toenable a reorganisation of the recirculation zone by breaking the spanwise homogeneity of theinteraction, yielding to a change of the reflected shock foot back and forth motion along the span.Additional simulations on three new configurations allowed to assess the effectiveness of microrampsin controlling the SBLI by comparing reduced size mVGs with more conventional ones
Maurel, Stéphane. „Étude par imagerie laser de la génération et de la rupture d'un écoulement tourbillonnaire compressé : situation modèle pour la validation de simulations aux grandes échelles dans les moteurs“. Toulouse, INPT, 2001. http://www.theses.fr/2001INPT035H.
Der volle Inhalt der QuelleLumet, Eliott. „Évaluation et réduction des incertitudes pour la simulation numérique de la dispersion atmosphérique à micro-échelle“. Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES003.
Der volle Inhalt der QuelleAir quality is severely degraded during events such as industrial accidents. Harmful gases and particles are released into the atmosphere and carried by the wind. In built environments, these pollutants can lead to local pollution peaks due to buildings blocking the flow, resulting in short-term health and environmental risks. Locating these peaks requires the use of models solving the fundamental equations of fluid dynamics and their interactions with the built environment. Despite their complexity, these models are subject to uncertainties that are partly linked to atmospheric conditions. The aim of this thesis is to build and validate a modeling system able of estimating these uncertainties and identifying possible dispersion scenarios. This is achieved by using tools derived from statistical learning and by informing the model with in-situ observations
Pinon, Grégory. „Modélisation numérique de jets transverses : application aux cas des inverseurs de poussée d'un avion en phase d'atterrissage“. Le Havre, 2005. http://www.theses.fr/2005LEHA0057.
Der volle Inhalt der QuelleThe aim of this PhD study is to predict the thrust reversers jets trajectories. These devices equip the aircrafts and produce opposite thrust, which brakes the aircraft in landingphase. The flow is ejected from the thrust reversers in a jet like form. This flow is complex and the mains characteristics are present even on a long distance from the nozzle's exit. For this study, we chose the vortex method more especially its « vortex blob » version. The resolution is unsteady and the discretisation is confined to the vortical zones. These zones are represented by vortex particles, carrying vortical information and followed in the flow in a lagrangian way. First, we make a short review of most jet like flows and we focus on their main characteristics, especially form jet issuing from a nozzle into a crossflow, where a contra-rotating vortex pair appears and is long-lived. Vortical structures are numerous in these kind of flow and they mostly depend on the injection ratio (ratio of the jet velocity compared to crossflow velocity). Secondly, treat the numerical aspects of the vortex method method. We use a three-dimensional Vortex Blob method, on which we have implemented a « Tree code » algorithm, a global reggridding of the flow and a « Particle strength Exchange » diffusion scheme, which unables us to use a Large Eddy Simulation (LES) model. On top of that, the whole code is parallelised using the MPI libraries. Then, we present some academical results of crossflow jet simulations. Nous study the temporal evolution of the vortical structures depending on the injection ratio, the temporal evoltion of the jet exit velocity, etc. . . Finally, we present a new hybrid method which couples eulerian simulations to our langrangian simulations in order to treat the industrial flow configurations. After some validation aspects of the new hybrid method with domain decomposition, we present several « complete » simulations of an aircraft in a landing phase. Finally, we are able to distingish re-ingestion case as they were experimentally obersed during wind tunnel testings
Guedot, Lola. „Développement de méthodes numériques pour la caractérisation des grandes structures tourbillonnaires dans les brûleurs aéronautiques : application aux systèmes d'injection multi-points“. Thesis, Rouen, INSA, 2015. http://www.theses.fr/2015ISAM0017/document.
Der volle Inhalt der QuelleThe reduction of pollutant emissions of aeronautical devices requires to optimize the design of the injection systems in the combustion chamber. The objective of this work is to improve the understandingof the flow dynamics in swirl stabilized burners. Large Eddy Simulation has become a major tool for the analysis of such flows. The steady increase in computational power enables to perform high-fidelity simulations, that generates a large amount of data, making it difficult to extract relevant information regarding the large scale phenomena. To this aim, massively parallel post-processing methods, suited for complex geometries, were developed in order to extract large-scale structures in turbulent flows. These methods were applied to simulations of spray flames in swirl burners, to get a better insight of how the large scale structures interact with the flame topology and the spray dynamics
Séverac, Eric. „Simulation des grandes échelles de haute précision d'écoulements tournants avec parois“. Aix-Marseille 3, 2008. http://www.theses.fr/2008AIX30024.
Der volle Inhalt der QuelleFully three-dimensional Large Eddy Simulation (LES) is developed with spectral approximation using a Spectral Vanishing Viscosity (SVV) technique. The SVV is first shown to keep the accuracy of the approximation. Secondly, turbulent flows are studied in an actual enclosed rotor-stator configuration. At low Reynolds number, we use a Direct Numerical Simulation (DNS) as reference. Then at Higher Reynolds number (from 10^5 to10^6), we provide detailed data on the flow and its boundary layer, including structures, physical properties, and statistical data. The results are favorably compared with the literature and an experiment conducted on an identical apparatus. We conclude that the SVV, coupled with a high order approximation, succeed in computing LES of complex flows when classical LES models fail
Albouze, Guillaume. „Simulation aux grandes échelles des écoulements réactifs non prémélangés“. Phd thesis, Toulouse, INPT, 2009. http://oatao.univ-toulouse.fr/7796/1/albouze.pdf.
Der volle Inhalt der QuelleQuillatre, Pierre. „Simulation aux grandes échelles d'explosions en domaine semi-confiné“. Phd thesis, Toulouse, INPT, 2014. http://oatao.univ-toulouse.fr/11851/1/quillatre.pdf.
Der volle Inhalt der QuelleChesnel, Jeremy. „Simulation aux Grandes Échelles de l'Atomisation, Application à l'Injection Automobile“. Phd thesis, Université de Rouen, 2010. http://tel.archives-ouvertes.fr/tel-00604870.
Der volle Inhalt der QuelleBoileau, Matthieu. „Simulation aux grandes échelles de l'allumage diphasique des foyers aéronautiques“. Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2007. http://tel.archives-ouvertes.fr/tel-00282523.
Der volle Inhalt der QuelleDefransure, Fabien. „Simulation aux grandes échelles de la combustion en charge stratifiée“. Châtenay-Malabry, Ecole centrale de Paris, 2004. http://www.theses.fr/2004ECAP0970.
Der volle Inhalt der QuelleN order to reduce greenhouse gas and pollutants emissions, car manufacturers investigate new combustion processes such as stratified load combustion by gasoline direct injection. The engine can work with a globally poor mixture and the flame propagates into an heterogeneous mixture where the equivalence ratio is variable. To answer to the need of physical understanding of flame propagation into such heterogeneous mixture, a Research Action called ``Stratified load combustion" has been created where numerical and experimental actions have been carried out. This work belongs to this research action and is devoted to the modelling of combustion in heterogeneous mixture. It is based on large eddy simulation (LES). The combustion model used is the artificially thickened flame model. This model has been first tested on an academic case of a laminar stratified flame. Because it didn't correctly describe stratified flame propagation, some evolutions of the model have been proposed and provided a better description of the flame propagation and burnt gases composition. All the simulations carried out on the experiments of the Research Action have showed the capacity of the thickened flame model to reproduce specific phenomena of a stratified flame such as the continuation of combustion even though the equivalence ratio met by the flame front is under the poor extinction limit. Moreover, the capacity of the model to naturally take into account pressure effects on flame speed has been exposed. That's why the artificially thickened flame model appears to be a good candidate to describe combustion in engines as well as for stratified load combustion as for homogeneous combustion
El, Shrif Ali. „Contrôle optimal par simulation aux grandes échelles d'un écoulement turbulent“. Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL035N/document.
Der volle Inhalt der QuelleTwo control strategies were successively implemented to reduce the drag and the turbulent kinetic energy of a plane channel flow in turbulent regime (Re[tau]=180). Wall transpiration (unsteady blowing/suction) with zero net mass flux is used as the control. The main objective was to prove that a large eddy simulation (LES) could be relevant as a reduced-order model of the Navier-Stokes equations and thus strongly reduce the numerical costs. A heuristic approach known as opposition control was initially employed. The results show that the energetic efficiency is maximum for a position of the detection plane different from that which corresponds to the maximum of drag reduction. In addition, our results confirm that the drag reduction decreases with the increase of the Reynolds number. Then, an optimal control procedure was used by considering different cost functional (drag, terminal turbulent kinetic energy, mean turbulent kinetic energy). At Re[tau] =100, control managed to fully relaminarize the flow (drag reduction of about 50%) by considering as cost functional the terminal kinetic energy. For this same cost functional, an important drag reduction of about 55% is still obtained at Re[tau] =180 but without reaching the relaminarization. Our results show that to minimize the flow drag, it is more effective to consider the kinetic energy as cost functional than directly the drag. Lastly, it is essential for the convergence of the minimization that the optimality system is solved on a sufficiently long time horizon
Özel, Ali. „Simulation aux grandes échelles des lits fluidisés circulants gaz-particule“. Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0090/document.
Der volle Inhalt der QuelleEulerian two fluid approach is generally used to simulate gas-solid flows in industrial circulating fluidized beds. Because of limitation of computational resources, simulations of large vessels are usually performed by using too coarse grid. Coarse grid simulations can not resolve fine flow scales which can play an important role in the dynamic behaviour of the beds. In particular, cancelling out the particle segregation effect of small scales leads to an inadequate modelling of the mean interfacial momentum transfer between phases and particulate shear stresses by secondary effect. Then, an appropriate modelling ac counting for influences of unresolved structures has to be proposed for coarse-grid simu-lations. For this purpose, computational grids are refined to get mesh-independent result where statistical quantities do not change with further mesh refinement for a 3-D peri-odic circulating fluidized bed. The 3-D periodic circulating fluidized is a simple academic configuration where gas-solid flow conducted with A-type particles is periodically driven along the opposite direction of the gravity. The particulate momentum and agitation equations are filtered by the volume averaging and the importance of additional terms due to the averaging procedure are investigated by budget analyses using the mesh independent result. Results show that the filtered momentum equation of phases can be computed on coarse grid simulations but sub-grid drift velocity due to the sub-grid correlation between the local fluid veloc- ity and the local particle volume fraction and particulate sub-grid shear stresses must be taken into account. In this study, we propose functional and structural models for sub- grid drift velocity, written in terms of the difference between the gas velocity-solid volume fraction correlation and the multiplication of the filtered gas velocity with the filtered solid volume fraction. Particulate sub-grid shear stresses are closed by models proposed for single turbulent flows. Models’ predictabilities are investigated by a priori tests and they are validated by coarse-grid simulations of 3-D periodic circulating, dense fluidized beds and experimental data of industrial scale circulating fluidized bed in manner of a posteriori tests
Bouheraoua, Lisa. „Simulation aux grandes échelles et modélisation de la combustion supersonique“. Thesis, Rouen, INSA, 2014. http://www.theses.fr/2014ISAM0022/document.
Der volle Inhalt der QuelleThis PhD study is focused on the large eddy simulation (LES) and on the modelisation of supersonic combustion as encountered in scramjet types engines. In this context, a LES study was performed for an hydrogen-air supersonic flame (Cheng’s flame) with three mesh refinement levels. The results obtained for mean and fluctuations of composition and temperature are compared to experimental measurements, and the impact of the grid resolution is established. Moreover, a modelisation of turbulent combustion in highly compressible flows is proposed based of tabulated chemistry approach. An analysis of the dynamics of shock/flame interaction was then conducted, and the presence of transient structures, which impact the flame stabilisation processes, was emphasized
Chesnel, Jérémy. „Simulation aux grandes échelles de l'atomisation : application à l'injection automobile“. Rouen, 2010. http://www.theses.fr/2010ROUES021.
Der volle Inhalt der QuelleLiquid injection takes an important part in many physical processes, especially within internal combustion engine (ICE). Up to know the Reynolds Averaged Navier-Stokes (RANS) approach has been widely used, both in Eulerian and Lagrangian framework. Several works on atomization have been done in our team developing the ELSA model. However, LES of atomization seems to be a necessarily step forward. In addition to standard LES method for turbulent flows, a special attention is necessarily to represent the interface. Two limit cases have to be considered : - The liquid surface can be well captured with the available mesh size (or filter size) then the LES formulation must recover the DNS methods used to track the interface (such as Level Set or VOF). -The liquid surface wrinkles size are smaller than the mesh size and the two-phase LES formulation must recover the LES used for spray where finally droplets are considered very small by comparison to the mesh size. In this work we present a LES method for two phase flow that can recover these two limits. It is shown that the unresolved SGS (Sub Grid Scale) term that appears in the phase function equation plays an important role, even if it is very small by comparison to the resolved contribution. Application of this method to the atomization of a Diesel jet is presented. LES results are then compared to a DNS data base
Lamalle, Damien. „Simulations aux grandes échelles de panaches libre et impactant“. Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0048/document.
Der volle Inhalt der QuelleFire Safety Engineering studies often rely on the use of Computational Fluid Dynamics, but several recent studies (e.g. Dalmarnock 2007, Arcueil Numérique 2009) have highlighted significant differences between experimental data and the results of numerical simulations. The numerical models are often rather sensitive to the choice of boundary conditions, and may depend on key parameters which are poorly understood. The research presented in this thesis addresses some of these questions, using the CFD code FDS to simulate a set of experimental test cases, and to test the sensitivity of the simulations to different input parameters. The general configuration studied is that of a thermal plume generated by a heated plate, either rising freely or else impacting on a ceiling. Radial profiles of 1st and 2nd order statistics of temperature and velocity agree well with published data, as does the axial variation of Mass, Momentum and Buoyancy fluxes, and the local Richardson number. A detailed study of the entrainment coefficient shows that this varies with distance from the heat source, between about 0.4 and 0.1; this is explained by the dependence of entrainment on the local Richardson number and the density difference between the plume and the ambient air. The comparison between simulations has also been used to investigate the applicability of different sub-grid scale models for this type of flow. Finally, a methodology has been developed for evaluating the sensitivity of the calculations to different input parameters, and the method has been applied to a test configuration representing a fire in a building. The results show the relative importance of both explicitly-defined parameters that characterize the situation (thermal power of the fire, ventilation regime inside the building) and implicit model parameters
Roux, Benjamin. „Couplage entre simulation système et simulation aux grandes échelles pour la simulation multi-échelles de moteurs à combustion interne“. Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066633/document.
Der volle Inhalt der QuelleThe decrease of greenhouse gases and pollutant emissions (nitrous oxides, carbon oxides, particles...) for spark ignited engines goes through the development of new technologies such as direct injection, turbocharging, downsizing, etc. However, the benefits of these technologies, which complexify the engines, are limited by the phenomena they intensify such as Cyclic Combustion Variability (CCV) and abnormal combustions. A thorough understanding of these phenomena is a cornerstone for the improvement of future engines. The aim of this work is to predict acyclic and transient phenomena in increasingly complex engines through the development, the validation and the use of a coupling method between Large-Eddy Simulation (LES) and system simulation. This thesis has demonstrated that simulating a complete industrial engine in 3D with LES to study its transient behavior is possible. The methodology developed in the present work was used to study the engine of the national research agency project SGEmac and a good agreement was obtained between the experiments and the tridimensional simulations. These results are the last validation step of the coupling method and demonstrate the capacity of the coupled solver to simulate the whole engine. The coupling method is then applied to study engine load and regime transients for the national research agency project ASTRIDE. The comparison between simulations and experiments show that the coupled solver can simulate CCV and transients, thus fulfilling its initial goal
Vié, Aymeric. „Simulation aux grandes échelles d'écoulements diphasiques turbulents à phase liquide dispersée“. Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2010. http://tel.archives-ouvertes.fr/tel-00620754.
Der volle Inhalt der QuelleTecher, Anthony. „Simulation aux grandes échelles implicite et explicite de la combustion supersonique“. Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2017. http://www.theses.fr/2017ESMA0020/document.
Der volle Inhalt der QuelleThis dissertation is devoted to the Large-eddy simulation (LES) study of a wall hydrogen underexpanded jet in a supersonic crossflow of vitiated air. This configuration is representative of flow conditions encountered in aerospace engines such as supersonic combustion ramjet (scramjets). Indeed, future of high-speed transport systems heavily depends on the development of this type of engine. Under such conditions, the high temperature flow of vitiated air is maintained supersonic in the combustion chamber to reduce effects of heating and dissociation. The mixing and combustion processes that develop downstream of the fuel jet are studied. This work is based on the use of a high fidelity numerical simulation: CREAMS (Compressible REActive Multi-species Solver) which is developed at the Pprime Institute. This computational solver makes use of high precision numerical schemes: a 3rd order Runge–Kutta scheme for the time integration combines with a 7th order WENO and 8th order centered scheme for the spatial discretisation. Non-reactive simulations allow to characterize the importance of shock/turbulence interactions with special attention paid to the description of the unresolved (i.e. sub-grid scale) scalar fluctuations. The reactive simulations allow to perform a detailed analysis of the stabilization mode and turbulent combustion regimes tha are encountered, thus providing valuable information about the possible adequacy of the available representation for these extreme conditions
Moureau, Vincent. „Simulation aux grandes échelles de l'aérodynamique interne des moteurs à piston“. Châtenay-Malabry, Ecole centrale de Paris, 2004. http://www.theses.fr/2004ECAP0952.
Der volle Inhalt der QuelleHecht, Nicolas. „Simulation aux grandes échelles des écoulements liquide-gaz : application à l'atomisation“. Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0026/document.
Der volle Inhalt der QuelleThis thesis is dedicated to improve atomization models for automobile injectors. The aim is to develop and evaluate numerical models to capture the liquid structure while they are being atomized from large scales to small sub grid scales in complex configurations. Initially, a calculation procedure is introduced for the transition to an Eulerian description of a spray into a Lagrangian description. In order not to lose the smallest fluid structures, they will be transformed into Lagrangian particles. During this process, an analysis is been performed with various physical parameters such as mass, momentum, or turbulent kinetic energy. The other part of this work is dedicated to the development of a LES (Large Eddy Simulation) for multiphase flow. The simulation of the spray requires a specific treatment of the interface. Two limiting cases are treated in the literature: • The interface may be captured by the mesh. At these locations, a conventional method of DNS (Direct Numerical Simulation) should be used, like the VOF method (Volume of Fluid). • When creating pleating smaller than the size of the mesh, the mesh can no longer match the interface. Then, the calculation must reproduce results from a LES method that take into account structures and drops smaller than the mesh size. Thus, the main problem is to define the configuration of the interface. The development of this model allows to obtain results in a configuration close to the Diesel injection's, which are then compared to a reference DNS
Aillaud, Pierre. „Simulations aux grandes échelles pour le refroidissement d'aubages de turbine haute-pression“. Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19731/1/AILLAUD_Pierre.pdf.
Der volle Inhalt der QuelleKnikker, Ronnie. „Analyse expérimentale de la combustion turbulente prémélangée pour la simulation aux grandes échelles“. Châtenay-Malabry, Ecole centrale de Paris, 2002. http://www.theses.fr/2002ECAP0741.
Der volle Inhalt der QuelleIafrate, Nicolas. „Simulation aux grandes échelles diphasique dans les moteurs downsizes à allumage commande“. Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/15721/1/Iafrate.pdf.
Der volle Inhalt der QuelleCharlette, Fabrice. „Simulation numérique de la combustion turbulente prémélangée par méthodes aux grandes échelles“. Châtenay-Malabry, Ecole centrale de Paris, 2002. http://www.theses.fr/2002ECAP0861.
Der volle Inhalt der QuelleSelle, Laurent. „Simulation aux grandes échelles des interactions flamme / acoustique dans un écoulement vrillé“. Toulouse, INPT, 2004. http://www.theses.fr/2004INPT001H.
Der volle Inhalt der QuelleMoldoveanu, Cristian-Emil Boisson Henri-Claude Moraru Florentin. „Simulation aux Grandes Échelles de tourbillons longitudinaux soumis à une turbulence extérieure intense“. Toulouse : INP Toulouse, 2008. http://ethesis.inp-toulouse.fr/archive/00000696.
Der volle Inhalt der QuelleThèse soutenue en co-tutelle. Titre provenant de l'écran-titre. Bibliogr. 120 réf.
Pascaud, Stéphane. „Vers la simulation aux grandes échelles des écoulements turbulents diphasiques réactifs : application aux foyers aéronautiques“. Phd thesis, Toulouse, INPT, 2006. http://oatao.univ-toulouse.fr/7497/1/pascaud1.pdf.
Der volle Inhalt der QuelleSengissen, Aloïs. „Simulation aux grandes échelles des instabilités de combustion : vers le couplage fluide / structure“. Phd thesis, Toulouse, INPT, 2006. http://oatao.univ-toulouse.fr/7428/1/sengissen1.pdf.
Der volle Inhalt der QuelleFransen, Rémy. „Simulation aux Grandes Échelles pour la modélisation aérothermique des aubages de turbines refroidies“. Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2013. http://tel.archives-ouvertes.fr/tel-00870685.
Der volle Inhalt der QuelleThobois, Ludovic. „Intérêt et faisabilité de la simulation aux grandes échelles dans les moteurs automobiles“. Toulouse, INPT, 2006. http://ethesis.inp-toulouse.fr/archive/00000292/.
Der volle Inhalt der QuelleEuropean environmental regulations obligate automotive manufacturers to develop less pollutant and less consuming engines. These engines are widely based on new combustion strategies, where mixing and aerodynamics need to be precisely controlled. Common aided development tools are no more adapted to predict accurately in space and time aerodynamics and mixing in new engines. RANS computations can not provide unsteady phenomena and engine test benches can not provide all the flow characteristics due to optical access. Large eddy simulation can be predicted through the motion of large turbulent eddies. The objectives of this work are to simulate engines geometries with the LES approach, to bring to front the advantages of the LES approach and to elaborate specific methodologies. On the one hand, LES is applied in steady-state flow benches in order to predict their discharge coefficient and their swirl number. Several flow benches have been tested. For all of them, LES results obtained are in agreement with experimental measurements. The final flow bench is the more realistic flow bench computed in this work. It is composed of two intake ports of a real Diesel engines. The LES approach gives insights into the understanding of flow generation and its dependance on valve lift. On the other hand, an ignition model (ADEL) is coupled to the turbulent combustion model TFLES. This model is then adapted to engine geometries, where thermodynamical conditions change. These two models are finally used to compute the combustion stroke of an indirect-injection gasoline engine. Four cycles of the engine are computed. The cycles obtained are in agreement with experimental cycles but they all differ. Cycle-to-cycle variations are analyzed in terms of mixing, aerodynamics, combustion and engine efficiency
Poitou, Damien. „Modélisation du rayonnement dans la simulation aux grandes échelles de la combustion turbulente“. Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT035G/document.
Der volle Inhalt der QuelleSimulation of turbulent combustion has gained high potential with the Large Eddy Simulation (LES) approach, allowing to predict unsteady turbulent reactive flows. In this context, taking into account radiation rises new fundamental and practical questions. Indeed the physics involved in radiation and in combustion are completely different : combustion is controlled by local exchanges and finite times whereas radiation is instantaneous and is based on non-local exchanges. In a first step, the impact of LES modelling of turbulent combustion on radiation is regarded. This question is treated in the more general frame of the turbulence-radiation interaction. From theoretical and numerical studies, it is shown that this interaction is weak in the LES context so that LES solutions can be directly coupled to radiative calculations, without further modelling. Then the unsteady coupling of radiation and turbulent combustion is realised. A key point is the reduction of calculation time of radiation, and several strategies are proposed. In particular a new global spectral model is introduced, using a tabulation technique and ensuring a sufficient level of accuracy. The radiative time calculation is finally decreased by two orders of magnitude, enabling the realization of a coupled calculation of a turbulent premixed flame
Lacaze, Guilhem. „Simulation aux Grandes Echelles de l'allumage de moteurs fusées cryotechniques“. Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2009. http://tel.archives-ouvertes.fr/tel-00429666.
Der volle Inhalt der QuelleRobert, Anthony. „Simulation aux Grandes Échelles des combustions anormales dans les moteurs downsizés à allumage commandé“. Phd thesis, Toulouse, INPT, 2014. http://oatao.univ-toulouse.fr/16783/1/ROBERT_Anthony.pdf.
Der volle Inhalt der QuelleLavedrine, Jacques. „Simulation aux grandes échelles de l'écoulement diphasique dans des modèles d'injecteur de moteurs aéronautiques“. Toulouse, INPT, 2008. http://ethesis.inp-toulouse.fr/archive/00000685/.
Der volle Inhalt der QuelleIn the issue of reducing pollutant emissions in aeronautical engines, Large Eddy Simulation (LES) allows a better understanding of the phenomena related to the fuel spray. In this thesis, the LES approach is first applied to an academic configuration with a polydisperse injector. This study goes through a comparison between numerical results and measurements, and constitutes a validation of the computational tool. This tool is then used to investigate the two-phase flow in a new industrial injector design through a comparison with experiments. This investigation also identifies the performances and potential improvements of such an injector. Finally, LES sensitivity to different injection strategies is assessed
Riber, Eleonore. „Développement de la méthode de simulation aux grandes échelles pour les écoulements diphasiques turbulents“. Toulouse, INPT, 2007. http://ethesis.inp-toulouse.fr/archive/00000531/.
Der volle Inhalt der QuelleThis work deals with numerical modeling of turbulent two-phase flows. It focuses on the phenomena of dispersion and preferential concentration of solid particles in a gas flow, and proposes a LES formulation of the eulerian mesoscopic approach, which raises two main issues. First, the set of equations for the dispersed phase that is non diffusive creates strong gradients difficult to handle numerically. Then, the unclosed terms are due both to ensemble averaging and volume filtering. In the presence study, a new numerical method more adapted to the dispersed phase equations is first proposed. Second, its robustness and accuracy are shown performing DNS of particle-laden decaying HIT flow. Finally, the LES eulerian mesoscopic model that was a priori proposed by Moreau (2006) is a posteriori validated in two complex geometries (Hishida et al. (1987) and Borée et al. (2001)) through comparisons with measurements and lagrangian results
Varoquie, Bertrand. „Etude expérimentale de la combustion turbulente non prémélangée pour la simulation aux grandes échelles“. Châtenay-Malabry, Ecole centrale de Paris, 2004. http://www.theses.fr/2004ECAP0950.
Der volle Inhalt der QuelleStaffelbach, Gabriel. „Simulation aux grandes échelles et analyse acoustique de turbines à gaz industrielles multi-brûleurs“. Toulouse, INPT, 2006. http://ethesis.inp-toulouse.fr/archive/00000245/.
Der volle Inhalt der QuellePollutant emissions restrictions have driven gas turbine manufacturers to employ new technologies and to operate these systems in extreme operating conditions where combustion instabilities may develop. Extended experimental and numerical studies are required to assess the danger to the turbine. For annular combustors, most tests are performed in reduced single-burner configurations. This thesis proposes to study using Large Eddy Simulation two phenomena that are neglected: burner/burner interaction and the impact of acoustic azimuthal modes on the burners. An additional issue considered is the effect of the pilot fuel injection on the flame stability
PIANA, JULIEN. „Etude de l'application des simulations aux grandes échelles à la combustion turbulente prémélangée“. Châtenay-Malabry, Ecole centrale de Paris, 1996. http://www.theses.fr/1996ECAP0529.
Der volle Inhalt der QuelleStefanin, Volpiani Pedro. „Modèle de plissement dynamique pour la simulation aux grandes échelles de la combustion turbulente prémelangée“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC005/document.
Der volle Inhalt der QuelleLarge eddy simulation (LES) is currently applied in a wide range of engineering applications. Classical LES combustion models are based on algebraic expressions and assume equilibrium between turbulence and flame wrinkling which is generally not verified in many circumstances as the flame is laminar at early stages and progressively wrinkled by turbulent motions. In practice, this conceptual drawback has a strong consequence: every computation needs its own set of constants, i.e. any small change in the operating conditions or in the geometry requires an adjustment of model parameters. The dynamic model recently developed adjust automatically the flame wrinkling factor from the knowledge of resolved scales. Widely used to describe the unresolved turbulent transport, the dynamic approach remains underexplored in combustion despite its interesting potential. This thesis presents a detailed study of a dynamic wrinkling factor model for large eddy simulation of turbulent premixed combustion. The goal of this thesis is to characterize, unveil pros and cons, apply and validate the dynamic modeling in different flow configurations
Oussama, Chikhaoui. „Simulations des grandes échelles et modélisations hybrides RANSE/LES pour le calcul d'écoulements turbulents de grande complexité“. Nantes, 2007. http://www.theses.fr/2007NANT2143.
Der volle Inhalt der QuelleThis PhD thesis deals with the Large Eddy Simulation and the hybrid RANSE/LES modelization. The abilityof ISIS-CFD flow solver, originally designed for solving Reynolds-Averaged Navier-Stokes equations, was extended to these different methods by integrating different turbulence models in order to provide a computing code able to deal with a wide range of academic and industrial complex problems. The models and numerical methods chosen and implemented were justified and validated over several academic test cases and comparisons of LES and hybrid simulations using different flow solvers have been successful. Hybrid methods studied showed a good ability to find expected solutions allowing a large saving in mesh resolution. A criterion based on the assessment of the residual of the momentum budget of the averaged flow is also proposed as an indicator of the numerical errors committed in LES and hybrid simulations. Finally, the simulation of complex turbulent flows using hybrid models have been undertaken. The use of RANS/LES models for the computation of the flow around a skidding simplified car model can reproduce faithfully and cheaply, the experimental observations of a turbulent flow of great complexity
Guillaume, Albouze. „SIMULATION AUX GRANDES ECHELLES DES ECOULEMENTS REACTIFS NON PREMELANGES“. Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2009. http://tel.archives-ouvertes.fr/tel-00451443.
Der volle Inhalt der QuellePuggelli, Stefano. „Vers une approche unifiée pour la simulation aux grandes échelles d'écoulements réactifs, diphasiques et turbulents“. Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR013/document.
Der volle Inhalt der QuelleThe recent limitations imposed by ICAO-CAEP, regulating NOx emissions, are leading to the implementation of lean burn concept in the aero-engine framework. From a design perspective, a depth insight on lean burn combustion is required and Computational Fluid Dynamics (CFD) can be a useful tool for this purpose. Several interacting phenomena are involved and various modelling strategies, with huge differences in terms of computational costs, are available. Nevertheless, up to now few numerical tools are able to account for the effects of liquid fuel preparation inside reactive computations. Spray boundary conditions are normally determined thanks to correlative approaches that are not able to cover the wide range of operating conditions and geometrical characteristics of aero-engine burners. However, as highlighted in the first part of the dissertation, where several literature test cases are analysed through numerical calculations, the impact of liquid preparation can be extremely important. Considerations based on correlative approaches may be therefore unreliable. More trustworthy predictive methods focused on fuel atomization are required. This research activity is therefore aimed at developing a general numerical tool, to be used in an industrial design process, capable of modelling the liquid phase from its injection till the generation of a dispersed spray subject to evaporation. The ELSA (Eulerian Lagrangian Spray Atomization) model, which is based on an Eulerian approach in the dense region and a Lagrangian one in the dilute zone, has been chosen to this end. The solver is able to deal with pure liquid up to the generation of a dispersed phase and to account for the breakup process through the introduction of the liquid-gas interface density. However, several limitations of such method arise considering its application in a highly swirled reactive environment like an aero-engine burner. Therefore, particular attention has been here devoted first to the study of the turbulent liquid flux term, inside the liquid volume fraction equation. This quantity is of paramount importance for a swirled flow-field, with high slip velocities between phases. A completely innovative modelling framework together with a new second order closure for this variable is proposed and validated on a literature jet in crossflow test case. Then, to handle a reactive environment, a novel evaporation model is integrated in the code and assessed against experimental results. Finally, an alternative way to derive the Drop Size Distribution (DSD) in ELSA context for the lagrangian injection is presented and assessed by means of Direct Numerical Simulations. Ultimately, this work introduces an innovative framework towards a uni- fied description of spray combustion in CFD investigations. The proposed approach should lead to a comprehensive description of fuel evolution in the injector region and to a proper characterization of the subsequent reacting flow-field. Several improvable aspects are also highlighted, pointing the way for further enhancements
Boger, Metta Maria. „Modélisation de sous-maille pour la simulation aux grandes échelles de la combustion turbulente prémélangée“. Châtenay-Malabry, Ecole centrale de Paris, 2000. http://www.theses.fr/2000ECAP0904.
Der volle Inhalt der QuelleBlin, Laurent. „Modélisation statistique et simulation des grandes échelles des écoulements turbulents. Application aux inverseurs de poussée“. Phd thesis, Université de Rouen, 1999. http://tel.archives-ouvertes.fr/tel-00011645.
Der volle Inhalt der Quelle(1) un écoulement décollé (marche descendante - calcul RANS),
(2) un écoulement cisaillé libre (couche de mélange plane - calculs RANS et LES),
(3) des écoulements présentant de fortes courbures des lignes de courant (conduite rectangulaire courbée (calcul RANS) et couche de mélange courbe - calculs RANS et LES). Ensuite, deux configurations simplifiées d'inverseurs de poussée à portes sont étudiées numériquement par simulations RANS et LES.
Truffin, Karine. „Simulation aux grandes échelles et identification acoustique des turbines à gaz en régime partiellement prémélangé“. Phd thesis, Toulouse, INPT, 2005. http://oatao.univ-toulouse.fr/7719/1/truffin1.pdf.
Der volle Inhalt der QuelleLeguille, Matthieu. „Étude du cliquetis dans un moteur industriel à allumage commandé par Simulation aux Grandes Échelles“. Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC081/document.
Der volle Inhalt der QuelleThe rising concerns about the environment have led car manufacturers to come up with new engine technologies, in order to reduce the impact of internal combustion engines on CO2 emissions. In this context, downsizing of turbocharged spark-ignition engines has become a commonly used technology, the advantage of which is to operate the engine under thermally more efficient high loads. However, these high loads favour the appearance of potentially damaging knock phenomena, which prevent the engine to fully exploit its potential. Because of cyclic combustion variability (CCV) in the engine, knock, which depends on the local conditions inside the combustion chamber, can appear at different locations and timings and not in all engine cycles. In this thesis, a Large-Eddy Simulation (LES) approach was selected to investigate and further improve our understanding of the appearance of knock. The study is based on the LES of a production engine, the RENAULT 1.2 TCe 115. For this engine, a set of 30 cycles was initially simulated at a single operating point, corresponding to a knocking point in the test bench database from RENAULT. The results were compared to experimental findings, both in terms of CCV and knock. Subsequently, a spark-timing sweep was simulated in order to enlarge the LES database to also include weaker and stronger knock levels. The resulting LES, which consists of 150 combustion cycles, was used to develop methodologies and tools with the objective to better characterize and understand knock. The computational access to any quantity inside the combustion chamber, together with the separate description with the present LES approach between the spark-triggered premixed flame propagation and auto-ignition, were exploited to characterize knock focusing on its source: autoignition in the fresh gases. Then, the developed methodologies and tools supported a detailed analysis of the mechanisms that control the knock onset. In particular, its link with CCV was explored. The results point out the impact of the cyclic variability in the premixed flame propagation speed and shape on knock
Martinez, Lionel. „Simulation aux grandes échelles de l'injection de carburant liquide dans les moteurs à combustion interne“. Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT040H/document.
Der volle Inhalt der QuelleCar manufacturers are facing increasingly severe regulations on pollutant emissions and fuel consumption. To respect these regulations, a better understanding of combustion processes is needed. Large Eddy Simulation (LES) is becoming a promising tool for such issues as it allows the study of complex unsteady phenomena which can not be analysed with RANS simulations or experiments. The present work is a step towards the LES of liquid injection in piston engines. The numerical code has been adapted to the specifications of Direct Injection which is more and more used in industry. Firstly, in order to avoid the difficulties linked to the 3D simulation of cavitation, primary break-up and turbulence in the near-nozzle region, an original methodology, based on an injector model, has been proposed. The idea is to initiate the spray physics downstream to the injector exit. Then LES 3D simulations of spray have been conducted using the Eulerian Mesoscopic approach extended to dense dispersed sprays by the addition of a particle-particle interactions model. The simulation results have been validated by comparison with experimental data in Diesel conditions with a low injection pressure. Furthermore a study on the spray dynamics has permitted to better understand its development and to find similarities with a turbulent gaseous jet. Additional simulations on realistic Diesel injection conditions have shown the good predictivity of LES in such cases. Finally, a first simulation of a Direct Injection Engine has been been carried out to assess the developments achieved in this work