Дисертації з теми "Combustion Simulations"
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Tajiri, Kazuya. "Simulations of combustion dynamics in pulse combustor." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/12175.
Повний текст джерелаSone, Kazuo. "Unsteady simulations of mixing and combustion in internal combustion engines." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/12171.
Повний текст джерелаHilbert, Renan. "Etude de la combustion turbulente non prémélangée et partiellement prémélangée par simulations numériques directes." Châtenay-Malabry, Ecole centrale de Paris, 2002. http://www.theses.fr/2002ECAP0856.
Повний текст джерелаLindberg, Jenny. "Experiments and simulations of lean methane combustion." Licentiate thesis, Luleå, 2004. http://epubl.luth.se/1402-1757/2004/61.
Повний текст джерелаShaw, Rebecca Custis Riehl. "Combining combustion simulations with complex chemical kinetics." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648248.
Повний текст джерелаAubagnac-Karkar, Damien. "Sectional soot modeling for Diesel RANS simulations." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0061/document.
Повний текст джерелаSoot particles emitted by Diesel engines cause major public health issues. Car manufacturers need models able to predict soot number and size distribution to face the more and more stringent norms.In this context, a soot model based on a sectional description of the solid phase is proposed in this work. First, the type of approach is discussed on the base of state of the art of the current soot models. Then, the proposed model is described. At every location and time-step of the simulation, soot particles are split into sections depending on their size. Each section evolution is governed by: • a transport equation;• source terms representing its interaction with the gaseous phase (particle inception, condensation surface growth and oxidation);• source terms representing its interaction with other sections (condensation and coagulation).This soot model requires the knowledge of local and instantaneous concentrations of minor species involved in soot formation and evolution. The kinetic schemes including these species are composed of hundreds of species and thousands of reactions. It is not possible to use them in 3D-CFD simulations. Therefore, the tabulated approach VPTHC (Variable Pressure Tabulated Homogeneous Chemistry) has been proposed. This approach is based on the ADF approach (Approximated Diffusion Flame) which has been simplified in order to be coupled with the sectional soot model. First, this tabulated combustion model ability to reproduce detailed kinetic scheme prediction has been validated on variable pressure and mixture fraction homogeneous reactors designed for this purpose. Then, the models predictions have been compared to experimental measurement of soot yields and particle size distributions of Diesel engines. The validation database includes variations of injection duration, injection pressure and EGR rate performed with a commercial Diesel fuel as well as the surrogate used in simulations. The model predictions agree with the experiments for most cases. Finally, the model predictions have been compared on a more detailed and academical case with the Engine Combustion Network Spray A, a high pressure Diesel spray. This final experimental validation provides data to evaluate the model predictions in transient conditions
Calhoon, William Henry Jr. "On subgrid combustion modeling for large-eddy simulations." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/12336.
Повний текст джерелаFujita, Akitoshi. "Numerical Simulations of Spray Combustion and Droplet Evaporation." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142213.
Повний текст джерелаBarsanti, Patricia Sylvia. "Simulations of confined turbulent explosions." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261538.
Повний текст джерелаCorrea, Chrys. "Combustion simulations in Diesel engines using reduced reaction mechanisms." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961521937.
Повний текст джерелаYu, Huidan. "Lattice Boltzmann equation simulations of turbulence, mixing, and combustion." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3081.
Повний текст джерелаPapadogiannis, Dimitrios. "Coupled Large Eddy Simulations of combustion chamber-turbine interactions." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14169/1/Papadogiannis_partie_1_sur_3.pdf.
Повний текст джерелаVasudevan, Raghavan. "Thermal diffusion coefficient modeling for high pressure combustion simulations." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202500574/.
Повний текст джерелаWood, Michael Philip. "Numerical simulations of temperature mapping in industrial combustion environments." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/numerical-simulations-of-temperature-mapping-in-industrial-combustion-environments(4d770272-abcd-45d4-8d7b-33cfffa61010).html.
Повний текст джерелаLI, YANJUN. "Flame Spread in Confined Spaces: Microgravity Experiments and Numerical Simulations." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1623863431539671.
Повний текст джерелаCollin, Félix. "Modeling and numerical simulations of two-phase ignition in gas turbine." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0053.
Повний текст джерелаIn order to meet the new international environmental regulations while maintaining a strong economic competitiveness, innovative technologies of aeronautical combustion chambers are developed. These technologies must guarantee fast relight in case of extinction, which is one of the most critical and complex aspects of engine design. Control of this phase involves a thorough understanding of the physical phenomena involved. In this thesis the full two-phase ignition sequence of an aeronautical engine has been studied, from the breakdown of the spark plug to thepropagation of the flame in the complete engine. For this purpose, Large-Eddy Simulations (LES) using a detailed description of the liquid phase (Euler-Lagrange formalism) and of the combustion process (Analytically Reduced Chemistry) were performed. The results also led to the development of a simplified model for the prediction of ignition probability map, which is particularly useful for the design of combustion chambers
Cuif, Sjöstrand Marianne. "Simulations Numériques Directes d’une méso-chambre de combustion : Mise en oeuvre et analyses." Thesis, Rouen, INSA, 2012. http://www.theses.fr/2012ISAM0022/document.
Повний текст джерелаMeso-combustion can be defined as the combustion regime where the involved lenghts scales are close but slightly larger than the quenching distance of the flame, tipically smaller than a cm. By taking advantage of the high energetic density of liquid hydrocarbons, it would become possible to build small-sized combustion-based long-lived lighter electrical power systems. However combsution phenomena at these meso-scales have their own shortcomings. Indeed, by decreasing the system size, the usual phenomenological balance betwenne chemical reactions, mixing, turbulence and heat transfer is changed. In the present work, we focus on the DNS calculation of a cubic meso-combsution chamber of 8 x 10 x 8 mm3. This works presents the implementation of the numerical strategy used, with a specific attention to the no-slip wall compressible boundary condition. We then present an analysis of this particular reactive flow. The results are useful for future modeling of such a combustor
Legier, Jean-Philippe. "Simulations numériques des instabilités de combustion dans les foyers aéronautiques." Toulouse, INPT, 2001. http://www.theses.fr/2001INPT029H.
Повний текст джерелаGoncalves, Dos santos Rogério. "Large Eddy simulations of turbulent combustion including radiative heat transfer." Châtenay-Malabry, Ecole centrale de Paris, 2008. http://www.theses.fr/2008ECAP1052.
Повний текст джерелаThe combustion is one of the principal ways to produced energy used nowadays, it is also a complex phenomenon, where the turbulent flow, chemical reactions, different phases and different heat transfer phenomena can interact. Better understanding of these interactions is essential to improve the actual combustion system and to developed the new ones. The goal of this thesis is to study the interaction of the turbulent combustion with the thermal radiation by the use of three-dimensional numerical simulation. For that, using a computational tool named CORBA, a code for the combustion Large Eddy Simulation (LES) was coupled with a radiative heat transfer code. This technique allows the exchange of information between the two codes without big changes in their structure, then it is possible to take advantages of the different characteristic time from each phenomenon in a high performance parallel computational environment. In a first time, two-dimensional simulation of a turbulent propane/air premixed flame stabilized downstream a triangular flame holder has been realised. After the changing of the twodimensional radiation code for another three-dimensional one, the same configuration was simulated in 3D. A mesh with more than 4. 7 millions cells for the combustion code (AVBP) and more than 3. 3 millions cells for the radiation code (DOMASIUM) are used. Results show a changing in the temperature and species fields, as well as in the flame dynamics when the thermal radiation was taken into account, with a minor intensity in the three-dimensional simulations. This method, also, shows that it is possible to perform 3D complex simulations in a industrial acceptable time
ZANONI, M. A. B. "Smoldering Combustion In Porous Media Kinetic Models For Numerical Simulations." Universidade Federal do Espírito Santo, 2012. http://repositorio.ufes.br/handle/10/4161.
Повний текст джерелаTecnologias avançadas para a geração de energia usando combustíveis não convencionais xisto betuminoso e seu semi-coque, areias betuminosas, petróleo extra-pesado e biomassa proveniente de resíduos sólidos urbanos e de lodo de esgoto - têm em comum processos termoquímicos compostos de complexas reações químicas. Este trabalho trata da formulação e otimização de mecanismos químicos normalmente envolvidos na pirólise do xisto betuminoso e na combustão do xisto betuminoso e seu semi-coque. Problemas inversos (usando o algoritmo de Levenberg-Marquardt) foram empregados para minimizar o erro entre os valores estimados e os dados de termogravimétria para os mecanismos de reação de 3 passos para a pirólise do xisto betuminos, e mecanismos de 4 e 3 passos para o xisto betuminoso e seu semi-coque, respectivamente. Os parâmetros cinéticos, tais como ordem de reação, fator pré-exponencial, energia de ativação e os coeficientes estequiométricos que afetam a secagem, as reações de oxidação, pirólise e descarbonatação foram estimadas com sucesso. Além disso, os erros estatísticos e residuais foram avaliados, resultando em um valor razoável para todas as estimativas e o mecanismo cinético proposto e estimado para a combustão do semi-coque foi aplicado em um código em meios porosos. Um estudo paramétrico entre o perfil de temperatura e a velocidade do ar, e o perfil de temperatura e a concentração de carbono fixo foi desenvolvido. Este estudo mostra que o perfil de temperatura é extremamente influenciado por estes parâmetros, confirmando que a propagação da frente é controlada pela injeção de O2. Palavras-chave: Xisto Betuminoso, Semi-Coque, Pirólise, Combustão, Estimação de Parâmetros, Problemas Inversos, Levenberg-Marquardt, Meios Porosos.
Tyves, Natalie. "Numerical simulations of turbulent non-premixed combustion in a regenerative furnace." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq52670.pdf.
Повний текст джерелаAbdelsamie, Abouelmagd [Verfasser]. "Direct numerical simulations of turbulent flow and spray combustion / Abouelmagd Abdelsamie." Magdeburg : Universitätsbibliothek, 2017. http://d-nb.info/1136955100/34.
Повний текст джерелаSensiau, Claude. "Simulations numériques des instabilités thermoacoustiques dans les chambres de combustion annulaires." Montpellier 2, 2008. http://www.theses.fr/2008MON20155.
Повний текст джерелаThermoacoustic instabilities are spontaneously excited by a feedback loop between an oscillatory combustion process and one of the natural acoustic modes of the combustor. This phenomenon causes loss of performance and severe damages to the engine. However, aeronautical engines or gaz turbines manufacturers often observe this kind of instabilities during the experiments. In this work we propose a methodology dedicated to the computation of thermoacoustic instabilities usable in an industrial context. The coupling between acoustics and combustion is accounted for thanks to a specific Helmholtz equation including a reacting flow term. Using a finite element approach leads to an algebraic non-linear eigenvalue problem with N dimensions (N the number of nodes in the mesh). A point fix algorithm mixed with subspace iterative methods (Arnoldi implemented in ARPACK or Jacobi-Davidson) permits to solve this problem efficiently. Because aeronautical combustors usually present an annular shape with 10 to 20 injectors located all over the circumference, a multi-referenced (n-tau) flame transfer function is proposed. This thermoacoustic model shows amplified or damped, standing or spinning azimuthal modes depending on the parameter tau. This methodology is integrated in the calculation chain QUIET (AVBP-N3S-NOZZLE-AVSP) and it is used to study thermoacoustic instabilities of the Turbomeca ARDIDEN engine. The results are shown to be in good accordance with large eddy simulations of the whole combustor
Ruiz, Anthony. "Unsteady Numerical Simulations of Transcritical Turbulent Combustion in Liquid Rocket Engines." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0009/document.
Повний текст джерелаIn the past fifty years, most design parameters of the combustion chamber of Liquid Rocket Engines (LREs) have been adjusted without a detailed understanding of combustion phenomena, because of both limited experimental diagnostics and numerical capabilities. The objective of the present thesis work is to conduct high-fidelity unsteady numerical simulations of transcritical reacting flows, in order to improve the understanding of flame dynamics in LRE, and eventually provide guidelines for their improvement. First real-gas thermodynamics and its impact on numerical schemes are presented. As Large-Eddy Simulation (LES) involves filtered equations, the filtering effects induced by real-gas thermodynamics are then highlighted in a typical 1D transcritical configuration and a specific real-gas artificial dissipation is proposed to smooth transcritical density gradients in LES. Then, a Direct Numerical Simulation (DNS) study of turbulent mixing and combustion in the near-injector region of LREs is conducted. In the non-reacting case, vortex shedding in the wake of the lip of the injector is shown to play a major role in turbulent mixing, and induces the formation of finger-like structures as observed experimentally in similar operating conditions. In the reacting case, the flame is attached to the injector rim without local extinction and the finger-like structures disappear. The flame structure is analyzed and various combustion modes are identified. Finally, a LES study of a transcritical H2/O2 jet flame, issuing from a coaxial injector with and without inner recess, is conducted. Numerical results are first validated against experimental data for the injector without recess. Then, the recessed configuration is compared to the reference solution and to experimental results, to scrutinize the effects of this design parameter on combustion efficiency
Palluotto, Lorella. "Prédiction du transfert radiatif au sein d’une flamme prémélangée swirlée à l’aide d’une méthode Quasi-Monte Carlo couplée à la simulation aux grandes échelles." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC034/document.
Повний текст джерелаThe prediction of wall fluxes is a significant aspect in the life cycle of combustors, since it allows to prevent eventual wall damages. Heat transfer from flame to the walls is driven, apart from convection, also by radiation of burnt gases inside the chamber. In order to correctly account for both convective and radiative contributions to wall fluxes, the simultaneous solution of the radiative transfer equation (RTE) and the governing equations for reactive flows is required. However, multi-physics simulations where MC methods are coupled to Large Eddy Simulation (LES), remain very costly. The purpose of this study is then to investigate improvements of MC methods, by using an alternative sampling mechanism for numerical integration usually referred to as Quasi-Monte Carlo (QMC) integration. In this study, QMC method is coupled to Large Eddy Simulation (LES) of a configuration where the radiation plays an important role: the methane-air flame investigated during the experimental campaign Oxytec. Coupled and non-coupled simulations are compared and their comparison with experimental data shows that thermal radiation has an impact on both flow and flame topology. Finally a good agreement is found between numerical wall fluxes and experimental conductive fluxes
Ayache, Simon Victor. "Simulations of turbulent swirl combustors." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/243609.
Повний текст джерелаLamouroux, Jean. "Modélidation de la combustion diluée par tabulation de la cinétique chimique." Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00905523.
Повний текст джерелаSainte-Rose, Bruno. "Simulations numériques d'écoulements réactifs massivement décollés par une approche hybride RANS/LES." Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00635538.
Повний текст джерелаSen, Baris Ali. "Artificial neural networks based subgrid chemistry model for turbulent reactive flow simulations." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31757.
Повний текст джерелаCommittee Chair: Menon, Suresh; Committee Member: Lieuwen, Timothy C.; Committee Member: Sankar, Lakshmi; Committee Member: Stoesser, Thorsten; Committee Member: Syed, Saadat; Committee Member: Walker, Mitchell. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Locci, Carlo [Verfasser], and Fabian [Akademischer Betreuer] Mauß. "Large Eddy Simulations Modelling of flameless combustion / Carlo Locci ; Betreuer: Fabian Mauß." Cottbus : BTU Cottbus - Senftenberg, 2015. http://d-nb.info/1114283355/34.
Повний текст джерелаKoren, Chai. "Modeling conjugate heat transfer phenomena for multi-physics simulations of combustion applications." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC001/document.
Повний текст джерелаOxycombustion is seen as one mean to attain the wished goals in terms of efficiency optimisation and Greenhouse Effect Gases emissions reduction for industrial furnaces. The extreme operating conditions, high pressure and temperature, lead to a strong interaction between the different phenomena which take place inside the combustion chambe r: Combustion, turbulence and heat transfer. To better design these futur oxyfuel processes, a mean to study the related physics with a reasonable computational cost and return time. Such studies require the use of high-fidelity numerical resolution tools, and in order to model the multi-physics interaction in a cost efficient way, code coupling. The operating conditions being extreme : High pressure and temperature, a strong interaction exists between the different phenomena occuring inside the chamber. To better understand the physics inside oxycombustion chambers,a multiphysics high-fidelity simulation methodology is developped
Colin, Olivier. "Simulations aux grandes échelles de la combustion turbulente prémélangée dans les statoréacteurs." Toulouse, INPT, 2000. http://www.theses.fr/2000INPT011H.
Повний текст джерелаAlmutlaq, Ahmed N. "Density-based unstructured simulations of gas-turbine combustor flows." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/13892.
Повний текст джерелаFranzelli, Benedetta Giulia. "Impact of the chemical description on direct numerical simulations and large eddy simulations of turbulent combustion in industrial aero-engines." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0066/document.
Повний текст джерелаA growing need for numerical simulations based on reliable chemistries has been observed in the last years in order to develop new technologies which could guarantee the reduction of the enviromental impact on air transport. The description of combustion requires the use of detailed kinetic mechanisms for most hydro-carbons. Their use in turbulent combustion simulation is still prohibitive because of their high computational cost. Reduced chemistries and tabulation methods have been proposed to over-come this problem. Since all these reductions have been developed for laminar configurations, this thesis proposes to evaluate their performances in simulations of turbulent configurations such as a DNS of a premixed Bunsen methane/air flame and a LES of an experimental PREC-CINSTA burner. The mechanisms are analysed in terms of flame structure, global burning parameters, flame length, prediction of major species concentrations and pollutant emissions. An a priori methodology based on one-dimensional unstrained and strained laminar flames to evaluate the mechanism capability to predict three-dimensional turbulent flame features is therefore proposed. On the one hand when building a new reduced scheme, its requirements should be fixed compromising the computational cost, the robustness of the chemical description and the desired quality of results. On the other hand, the quality of DNS or LES results in three-dimensional configurations could be anticipated testing the reduced mechanism on laminar one-dimensional premixed unstrained and strained flames
Obando, Vega Pedro Javier. "Filtered Tabulated Chemistry for LES of non-premixed combustion." Doctoral thesis, Universite Libre de Bruxelles, 2021. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/317788.
Повний текст джерелаDoctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
Cuif, Sjöstrand Marianne. "Simulations Numériques Directes d'une méso-chambre de combustion : Mise en oeuvre et analyses." Phd thesis, INSA de Rouen, 2012. http://tel.archives-ouvertes.fr/tel-00845259.
Повний текст джерелаRuiz, Anthony. "Simulations Numériques Instationnaires de la Combustion Turbulente et Transcritique dans les Moteurs Cryotechniques." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2012. http://tel.archives-ouvertes.fr/tel-00691975.
Повний текст джерелаKewlani, Gaurav. "Large eddy simulations of premixed turbulent flame dynamics : combustion modeling, validation and analysis." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93863.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 293-300).
High efficiency, low emissions and stable operation over a wide range of conditions are some of the key requirements of modem-day combustors. To achieve these objectives, lean premixed flames are generally preferred as they achieve efficient and clean combustion. A drawback of lean premixed combustion, however, is that the flames are more prone to dynamics. The unsteady release of sensible heat and flow dilatation in combustion processes create pressure fluctuations which, particularly in premixed flames, can couple with the acoustics of the combustion system. This acoustic coupling creates a feedback loop with the heat release that can lead to severe thermoacoustic instabilities that can damage the combustor. Understanding these dynamics, predicting their onset and proposing passive and active control strategies are critical to large-scale implementation. For the numerical study of such systems, large eddy simulation (LES) techniques with appropriate combustion models and reaction mechanisms are highly appropriate. These approaches balance the computational complexity and predictive accuracy. This work, therefore, aims to explore the applicability of these methods to the study of premixed wake stabilized flames. Specifically, finite rate chemistry LES models that can effectively capture the interaction between different turbulent scales and the combustion fronts have been implemented, and applied for the analysis of premixed turbulent flame dynamics in laboratory-scale combustor configurations. Firstly, the artificial flame thickening approach, along with an appropriate reduced chemistry mechanism, is utilized for modeling turbulence-combustion interactions at small scales. A novel dynamic formulation is proposed that explicitly incorporates the influence of strain on flame wrinkling by solving a transport equation for the latter rather than using local-equilibrium-based algebraic models. Additionally, a multiple-step combustion chemistry mechanism is used for the simulations. Secondly, the presumed-PDF approach, coupled with the flamelet generated manifold (FGM) technique, is also implemented for modeling turbulence-combustion interactions. The proposed formulation explicitly incorporates the influence of strain via the scalar dissipation rate and can result in more accurate predictions especially for highly unsteady flame configurations. Specifically, the dissipation rate is incorporated as an additional coordinate to presume the PDF and strained flamelets are utilized to generate the chemistry databases. These LES solvers have been developed and applied for the analysis of reacting flows in several combustor configurations, i.e. triangular bluff body in a rectangular channel, backward facing step configuration, axi-symmetric bluff body in cylindrical chamber, and cylindrical sudden expansion with swirl, and their performance has been be validated against experimental observations. Subsequently, the impact of the equivalence ratio variation on flame-flow dynamics is studied for the swirl configuration using the experimental PIV data as well as the numerical LES code, following which dynamic mode decomposition of the flow field is performed. It is observed that increasing the equivalence ratio can appreciably influence the dominant flow features in the wake region, including the size and shape of the recirculation zone(s), as well as the flame dynamics. Specifically, varying the heat loading results in altering the dominant flame stabilization mechanism, thereby causing transitions across distinct- flame configurations, while also modifying the inner recirculation zone topology significantly. Additionally, the LES framework has also been applied to gain an insight into the combustion dynamics phenomena for the backward-facing step configuration. Apart from evaluating the influence of equivalence ratio on the combustion process for stable flames, the flame-flow interactions in acoustically forced scenarios are also analyzed using LES and dynamic mode decomposition (DMD). Specifically, numerical simulations are performed corresponding to a selfexcited combustion instability configuration as observed in the experiments, and it is observed that LES is able to suitably capture the flame dynamics. These insights highlight the effect of heat release variation on flame-flow interactions in wall-confined combustor configurations, which can significantly impact combustion stability in acoustically-coupled systems. The fidelity of the solvers in predicting the system response to variation in heat loading and to acoustic forcing suggests that the LES framework can be suitably applied for the analysis of flame dynamics as well as to understand the fundamental mechanisms responsible for combustion instability. KEY WORDS - large eddy simulation, LES, wake stabilized flame, turbulent premixed combustion, combustion modeling, artificially thickened flame model, triangular bluff body, backward facing step combustor, presumed-PDF model, flamelet generated manifold, axi-symmetric bluff body, cylindrical swirl combustor, particle image velocimetry, dynamic mode decomposition, combustion instability, forced response.
by Gaurav Kewlani.
Ph. D.
Fossi, Athanase Alain. "Numerical simulations of stationary and transient spray combustion for aircraft gas turbine applications." Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27597.
Повний текст джерелаThe development of current and future aero gas turbine engines is mainly focused on the safety, the performance, the energy consumption, and increasingly on the reduction of pollutants and noise level. To this end, the engine’s design phases are subjected to improving processes continuously through experimental and numerical investigations. The present thesis is concerned with the simulation of transient and steady combustion regimes in an aircraft gas turbine operating under various combustion modes. Particular attention is paid to the accuracy of the results, the computational cost, and the ease of handling the numerical tool from an industrial standpoint. Thus, a commercial Computational Fluid Dynamics (CFD) code widely used in industry is selected as the numerical tool. A CFD methodology consisting of its advanced turbulence and combustion models, coupled with a subgrid spark-based ignition model, is formulated with the final goal of predicting the whole ignition sequence under cold start and altitude relight conditions, and the main flame trends in the steady combustion regime. At first, attention is focused on the steady combustion regime. Various CFD methodologies are formulated using three turbulence models, namely, the Unsteady Reynolds-Averaged Navier-Stokes (URANS), the Scale-Adaptive Simulation (SAS), and the Large Eddy Simulation (LES) models. To appraise the relevance of incorporating a realistic chemistry model and chemical non-equilibrium effects, two different assumptions are considered, namely, the infinitely-fast chemistry through the partial equilibrium model, and the finite-rate chemistry through the diffusion flamelet model. For each of the two assumptions, both one-component and two-component fuels are considered as surrogates for kerosene (Jet A-1). The resulting CFD models are applied to a swirl-stabilized combustion chamber to assess their ability to retrieve the spray flow and combustion properties in the steady combustion regime. Subsequently, the ratios between the accuracy of the results and the computational cost of the three CFD methodologies are explicitly compared. The second intermediate study is devoted to the ignition sequence preceding the steady combustion regime. A bluff-body stabilized burner based on gaseous fuel, and employing a spark-based igniter, is considered to calibrate the CFD model formulated. This burner of relatively simple geometry can provide greater understanding of complex reactive flow features, especially with regard to ignitability and stability. The most robust of the CFD methodologies formulated in the previous configuration is reconsidered. As this burner involves a partially-premixed combustion mode, a combustion model based on the mixture fraction-progress variable formulation is adopted with the assumptions of infinitely-fast chemistry and finite-rate chemistry through the Bray-Moss-Libby (BML) and Flamelet Generated Manifold (FGM) models, respectively. The ignition model is first customized by implementing the properties of the flame considered. Thereafter, the customized ignition model is coupled to the LES solver and combustion models based on the two above-listed assumptions. To assess the predictive capabilities of the resulting CFD methodologies, the latter are used to predict ignition events resulting from the spark deposition at various locations of the burner, and the results are quantitatively and qualitatively validated by comparing the latter to their experimental counterparts. Finally, the CFD methodology validated in the gaseous configuration is extended to spray combustion by first coupling the latter to the spray module, and by implementing the flame properties of kerosene in the ignition model. The resulting CFD model is first applied to the swirl-stabilized combustor investigated previously, with the aim of predicting the whole ignition sequence and improving the previous predictions of the combustion properties in the resulting steady regime. Subsequently, the CFD methodology is applied to a scaled can combustor with the aim of predicting ignition events under cold start and altitude relight operating conditions. The ability of the CFD methodology to predict ignition events under the two operating conditions is assessed by contrasting the numerical predictions to the corresponding experimental ignition envelopes. A qualitative validation of the ignition sequence is also done by comparing the numerical ignition sequence to the high-speed camera images of the corresponding ignition event.
Wang, William K. "Experimental Results and Computer Simulations for Post-Combustion Carbon Dioxide Removal Using Limestone." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1262100381.
Повний текст джерелаPIANA, 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.
Повний текст джерелаAmaya, Jorge. "Unsteady coupled convection, conduction and radiation simulations on parallel architectures for combustion applications." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0044/document.
Повний текст джерелаIn the aeronautical industry, energy generation relies almost exclusively in the combustion of hydrocarbons. The best way to improve the efficiency of such systems, while controlling their environmental impact, is to optimize the combustion process. With the continuous rise of computational power, simulations of complex combustion systems have become feasible, but until recently in industrial applications radiation and heat conduction were neglected. In the present work the numerical tools necessary for the coupled resolution of the three heat transfer modes have been developed and applied to the study of an helicopter combustion chamber. It is shown that the inclusion of all heat transfer modes can influence the temperature repartition in the domain. The numerical tools and the coupling methodology developed are now opening the way to a good number of scientific and engineering applications
Benezech, Laurent Jean-Michel Dimotakis Paul E. "Premixed hydrocarbon stagnation flames : experiments and simulations to validate combustion chemical-kinetic models /." Diss., Pasadena, Calif. : California Institute of Technology, 2008. http://resolver.caltech.edu/CaltechETD:etd-05302008-113043.
Повний текст джерелаBénard, 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.
Повний текст джерелаDesigning 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
Duran, Garcia-Rama Ignacio Luis. "Prediction of combustion noise in modern aero engines combining large eddy simulations and analytical methods." Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0138.
Повний текст джерелаCombustion noise is increasing its relative contribution to aircraft noise, while other sources are being reduced and new low-NOx emission combustion chambers being built. Two mechanisms are responsible for this noise source: direct noise in which acoustic waves are generated by the flame and propagate to the outlet of the aero-engine, and indirect noise, where entropy waves generate noise as they are accelerated and decelerated in the turbine stages. In this work the analytical models used for the propagation of waves through non-homogeneous flows, including the generation of indirect noise, are revised and extended. In the first part, the quasi-1D case is studied, extending the analytical method to non-zero frequencies and validating the results with numerical methods and experimental data. In the second part, the 2D method for the case of compact turbine blades is studied and validated using numerical simulations of a rotating blade and of a complete turbine stage. Finally, in the third part of this thesis, these models are combined with reactive and compressible Large Eddy Simulations (LES) of combustion chambers to build a hybrid approach, named CHORUS, able to predict combustion noise
Felden, Anne. "Development of Analytically Reduced Chemistries (ARC) and applications in Large Eddy Simulations (LES) of turbulent combustion." Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19226/1/Felden.pdf.
Повний текст джерелаRefahi, Sorour. "Développement d'un code de transfert radiatif et de son couplage avec un code LES." Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00832350.
Повний текст джерелаLoyez, Marc Jason. "Free Lagrange simulations of flame/vortex interactions, including detailed finite rate chemical kinetics and heat release." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241965.
Повний текст джерелаLabarrere, Laure. "Etude théorique et numérique de la combustion isochore appliquée au cas du thermoreacteur." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0028.
Повний текст джерелаA major challenge for the aircraft industry is to improve engine efficiency and to reduce pollutant emissions for economic, technical and environmental reasons. Aeronautical gas turbines have enjoyed a constant improvement for more than 60 years. This technology seems to have reached such efficiency levels that a technological breakthrough is necessary. Constant Volume Combustion (CVC) offers significant gain in consumption and could replace classical constant pressure combustion technologies, currently used in aeronautical engines. Mechanisms involved in isovolume combustion are not accurately controlled in the context of aeronautical chambers. Experimental, theoretical and numerical studies should provide a better understanding of CVC devices. The objective of this thesis is to develop simulation tools to study the thermoreacteur concept. First, a zero-dimensional (0D) simulation tool is developed to describe the evolution of a CVC cycle. Models based on experimental correlations are used to build the 0D tool. Parameters have to be determined from numerical simulations. Today, the 3D simulation of a CVC system is possible thanks to the recent progress of the LES (Large Eddy Simulation) methods developed at CERFACS. Simulations of the thermoreacteur concept have been carried out, and compared to experimental results obtained at the Pprime laboratory. Three operating points have been calculated. The main conclusion is the existence of significant cyclic variations which are observed in the experiment and analyzed in the LES: the local flow velocity at spark timing and the level of residuals gases are the major factors leading to cyclic variations
Gutiérrez, Daniel. "Green Fuel Simulations." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79244.
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