Dissertations / Theses on the topic 'Two phase flow combustion'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Two phase flow combustion.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Carabateas, Nicolas. "Two phase flow and combustion in S.I. engines." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265853.
Sankaran, Vaidyanathan. "Sub-grid Combustion Modeling for Compressible Two-Phase Flows." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5274.
Rochette, Bastien. "Modeling and simulation of two-phase flow turbulent combustion in aeronautical engines." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0059.
Nowadays, more than 80% of the energy consumed on Earth is produced by burning fossil fuels. Alternative solutions to combustion are being developed but the specific constraints related to air transport do not make it possible to currently power engines without introducing a technological breakthrough. These findings explain the research activity to improve the knowledge and the control of combustion processes to design cleaner, and more efficient aeronautical engines. In this framework, Large Eddy Simulations (LES) have become a powerful tool to better understand combustion processes and pollutant emissions. This PhD thesis is part of this context and focuses on the models and numerical strategies to simulate with more accuracy turbulent gaseous and two-phase reacting flows in the combustion chamber of aeronautical engines. First, a generic and self-adapting method for flame front detection and thickening has been developed for the TFLES model, and validated on several academic configurations of increasing complexity. This generic approach is then evaluated in the LES of a laboratory-scale burner and compared to the classical thickening method. Results show a more accurate thickening in post-flame regions. Second, from the analysis of 1-D homogeneous laminar spray flames where the dispersed phase has a relative velocity compared to the carrier phase, two analytical formulations for the spray flame propagation speed have been proposed and validated. The agreement between the overall trend of both the measured/estimated spray flame speeds demonstrates that the model and its parameters correctly take into account the main physical mechanisms controlling laminar spray flames. Finally, the state-of-the-art TFLES models were tested on complex turbulent gaseous and two-phase reacting configurations. The pros and cons of these models were investigated to contribute to the understanding of the mechanisms related to turbulent combustion, and to propose a LES modeling strategy to improve the fidelity of reactive simulations
Collin, Félix. "Modeling and numerical simulations of two-phase ignition in gas turbine." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0053.
In 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
Thawley, Scott. "Spatio-temporal Characteristics of a Spray from a Liquid Jet in Crossflow." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/31276.
Master of Science
Caceres, Marcos. "Impact of transverse acoustic modes on a linearly arranged two-phase flow swirling flames." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR01/document.
The energy needs of population around the word are continuously increasing. For instance, forecasts indicates an important grow of the request of the aeronautic transportation sector. It is necessary to continue the research efforts to get more performants and less contaminating systems. New concepts for combustion have been developed and introduced to the gas turbine industry. Among these concepts it is found technologies based on lean-premixed combustion or lean-premixed prevaporized combustion when liquid fuels are employed. These novel energetic systems, making use of lean combustion, are promising to meet the future norms about pollutant emissions, but this make them more sensitive to combustion instabilities that limit their operating range and can lead to irreversible damage. In this domain, many questions still need to be considered. In particular that of the behavior of two-phase flow swirling flames subjected to acoustic perturbations. Indeed most of aero-engines operate with this type of flames, but the dynamics and mutual interaction of these flames, as they are submitted to acoustic perturbation, are not yet well understood. This work addresses these issues and gives some understanding elements for the mechanisms driving the response of the flow and of the flame to acoustic perturbations and delivers data to validate models predicting unstable operating points.The experimental bench employed for this work is TACC-Spray. It has been designed and developed in the CORIA laboratory during this PhD thesis which is inscribed in the framework of the ANR FASMIC project. The injections system that equips this bench is composed by three swirled injectors fed with a liquid fuel (here n-heptane), developed by the EM2C laboratory. They are linearly arranged in the bench such that this represents an unwrapped sector of an annular chamber. The setup, being new and complex, needed technical solutions developed during this work and applied then in order to equip TACC-Spray with pressure and temperature sensors, a photomultiplier as well as adequate optic diagnostics (LDA, PDA, high speed imaging systems). In this study, the energetic system, composed by the two-phase swirling flow and the spray flame, has been submitted to the impact of a transverse acoustic mode excited within the acoustic cavity. The system response has been studied as a function of its location in the acoustic field. Three basins of influence of the acoustic field on the energetic system have been chosen, namely: (i) the pressure antinode characterized mainly by strong pressure fluctuations, (ii) the intensity antinode where important acoustic pressure and velocity gradients are present, (iii) the velocity antinode with strong velocity fluctuations where the acoustic pressure is residual. The approach of the study presented here is to investigate in first place the energetic system free of acoustic forcing. The results concerning this first study are presented in the Part I of this manuscript. In second place, the energetic system is placed in each of the location of interest within the acoustic field and the response of the air flow without combustion, that of the two-phase flow with combustion and finally that of the spray flames, are systematically investigated. The results of the study under acoustic forcing are shown in Part II of the manuscript
Eyssartier, Alexandre. "LES of two-phase reacting flows : stationary and transient operating conditions." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0011/document.
Ignition and altitude reignition are critical issues for aeronautical combustion chambers. The success of ignition depends on multiple factors, from the characteristics of the igniter to the spray droplet size or the level of turbulence at the ignition site. Finding the optimal location of the igniter or the potential of ignition success of a given energy source at a given location are therefore parameters of primary importance in the design of combustion chambers. The purpose of this thesis is to study forced ignition of aeronautical combustion chambers. To do so, Large Eddy Simulations (LES) of two-phase reacting flows are performed and analyzed. First, the equations of the Eulerian formalism used to describe the dispersed phase are presented. To validate the successive LES, experimental data from the MERCATO bench installed at ONERA Fauga-Mauzac are used. It allows to validate the two-phase evaporating flow LES methodology and models prior to its use to other flow conditions. The statistically stationary two-phase flow reacting case is then compared to available data to evaluate the model in reacting conditions. This case is more deeply studied through the analysis of the characteristics of the flame. This last one appears to experience very different combustion regimes. It is also seen that the determination of the most appropriate methodology to compute two-phase flow flame is not obvious. Furthermore, two different methodologies may both agree with the data and still have different burning modes. The ability of the LES to correctly compute burning two-phase flow being validated, LES of the transient ignition phenomena are performed. The experimentally observed sensitivity of ignition to initial conditions, i.e. to sparking time, is recovered with LES. The analysis highlights the major role played by the spray dispersion in the development of the initial flame kernel. The use of LES to compute ignition sequences provides a lot of information about the ignition phenomena, however from an industrial point of view, it does not give an optimal result, unless all locations are tested, which brings the CPU cost to unreasonable values. Alternatives are hence needed and are the objective of the last part of this work. It is proposed to derive a local ignition criterion, giving the probability of ignition from the knowledge of the unsteady non-reacting two-phase (air and fuel) flow. This model is based on criteria for the phases of a successful ignition process, from the first kernel formation to the flame propagation towards the injector. Then, comparisons with experimental data on aeronautical chambers are done and show good agreement, indicating that the proposed ignition criterion, coupled to a Large Eddy Simulation of the stationary evaporating two-phase non-reacting flow, can be used to optimize the igniter location and power
Nelson, Lauren May. "Rayleigh Flow of Two-Phase Nitrous Oxide as a Hybrid Rocket Nozzle Coolant." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/284.
Akritopoulos, Michail. "Combustion modelling of dispersed two-phase flows, applied in circulating fluidised beds." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414215.
Overbrüggen, Timo van [Verfasser], Wolfgang [Akademischer Betreuer] Schröder, and Reinhold [Akademischer Betreuer] Kneer. "Experimental analysis of the two-phase flow field in internal combustion engines / Timo van Overbrüggen ; Wolfgang Schröder, Reinhold Kneer." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1125911573/34.
Overbrüggen, Timo van Verfasser], Wolfgang [Akademischer Betreuer] Schröder, and Reinhold [Akademischer Betreuer] [Kneer. "Experimental analysis of the two-phase flow field in internal combustion engines / Timo van Overbrüggen ; Wolfgang Schröder, Reinhold Kneer." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1125911573/34.
YAMAMOTO, Kazuhiro, and 和弘 山本. "メタルハニカム内のディーゼル微粒子燃焼シミュレーション." 一般社団法人 日本機械学会, 2008. http://hdl.handle.net/2237/19798.
Mocquard, Clément. "Simulations aux grandes échelles de la postcombustion dans les moteurs d'avion de chasse." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP026.
Afterburners - also called reheat, augmentor or sequential burners - are found both in the gas turbine industry and aircraft engines. This work focuses on aircraft engines afterburners which are located downstream of the low-pressure turbines. Aircraft's afterburners have a significantly lower efficiency than the primary burners because they release heat at a lower pressure part of the Brayton cycle. However, they become attractive when the thrust to provide to the aircraft varies a lot during the flight, and when trying to improve maximum thrust. It is mainly the case for high-speed/supersonic flights, short distance take-off, or tactical maneuvers. To meet such requirements, the propulsion engine has to be more versatile, and the extra thrust provided by an afterburner can prove useful. While supersonic aircrafts are almost exclusively encountered in military applications, an exception was the supersonic Concorde commercial jet which needed an afterburner to meet its thrust requirements. On modern aircrafts, the specifications concerning the global engine efficiency, lifetime, maximum thrust, emissions etc. have led to more and more constraints on the augmentor design. The architectures and design methods which have been developed in the past decades are now unable to satisfy today's constraints and new designs are being investigated. In the industry, engineers nowadays rely on numerical tools to find the best solutions to their problems. In particular, for propulsion systems, unsteady fluid dynamic and combustion studies, Large Eddy Simulations (LES), which used to be prohibitively expensive in the past, is becoming increasingly used by industrial design offices. Despite the increase in computational power, LES of real-scale complex 3D geometries are still extremely expensive, and the present work aims at providing models allowing to find a good compromise between cost and accuracy of LES. Moreover, most of the research efforts so far focused mainly on the modelling of combustion phenomenon in primary combustion chambers, where a fuel/air mixture is burnt at relatively low temperature. In an afterburner, the fuel (kerosene) is injected in very hot burnt gas coming from the primary combustion chamber, and the models usually used from primary chambers can not be used directly to compute afterburners. In a first part, a new 2-step chemical scheme was developed for kerosene combustion at the conditions encountered in afterburners. Secondly, an extension of Thickened Flame model is proposed in order to better reproduce auto-ignition events which are likely to occur in afterburners. A Euler-Lagrange approach was used to model the liquid fuel injection, atomization, and evaporation. Then, the models developed during this thesis are used to compute a real scale lab experiment as well as a simplified geometry representative of the Safran M88 aircraft engine afterburner. Those last simulations highlight the complexity of the reactive flow inside afterburners and the usefulness of LES in the design of afterburning aircraft engines
Monmont, Franck. "Experimental and theoretical study of the two-phase flow inside a lean premixed prevaporised combustor." Thesis, Cranfield University, 1999. http://dspace.lib.cranfield.ac.uk/handle/1826/10576.
Gosset, Antoine. "Modélisation de la combustion de particules d'aluminium en milieu gazeux sous pression." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP004.
Following detonation of an under-oxygenated explosive, detonation products are dispersed in the air, reacting with the surrounding air to produce a fireball. This phase is known as afterburning, and plays a major role in the release of energy from the explosive. Among detonation products, aluminum stands out for its high energy density. However, the rich diversity of physical phenomena involved in aluminum combustion, as well as the extreme physical conditions under which afterburning takes place, make experimental measurements difficult to extract. Numerical studies are therefore necessary to provide quantitative input to fast hydrodynamics codes. This thesis follows on from the work of S. Courtiaud on afterburning and J. Suarez on aluminum modeling. This thesis focuses initially on the implementation of a robust HLLC numerical scheme, with MUSCL reconstruction, in the combustion CFD code AVBP set up by CERFACS. The aim is to solve robustness problems in the presence of strong pressure and temperature gradients. This numerical scheme has proved its worth, giving results similar to a centered second-order scheme, but with considerable time savings thanks to a simplified initialization of a premixed 1D aluminum flame. On the other hand, another approach to aluminum combustion is proposed, linked to experimental studies carried out at the ICARE laboratory in Orléans, where we now consider a global point of view based on a characteristic combustion time. This model is validated on the one hand by a comparison with a model containing a detailed chemistry of aluminum combustion, on the premixed 1D flame configuration.This model is also validated by a parametric study of the 1D flame, revealing laminar flame velocities and burnt gas temperatures close to the literature results. In addition, the model is tested under constant-volume combustion conditions, showing similar pressure trends to those available in the literature on the severity of dust explosions. Finally, the model is used to suggest ways of understanding the influence of particle diameter polydispersion on laminar flame velocity. The work concludes with a post-detonation calculation of aluminized explosives using the robust scheme and including the aluminum combustion model developed. The aim of this calculation is to demonstrate current modeling capabilities and provide a first insight into the influence of aluminum combustion on post-detonation, enabling future work to get to the heart of the matter. Furthermore, in the current climate context, the interest of metallic fuels as a low-carbon energy vector introduces another objective to this thesis, which is to build on the knowledge acquired on aluminum combustion in order to propose efficient models that will enable us to consider aluminum, and more generally metals, as reliable and controlled fuels for a necessary energy transition
Emre, Oguz. "Modeling of spray polydispersion with two-way turbulent interactions for high pressure direct injection in engines." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0029/document.
The ability to simulate two-phase flows is of crucial importance for the prediction of internal combustion engine (ICE) performance and pollutant emissions. The direct injection of the liquid fuel inside the combustion chamber generates a cloud of polydisperse droplets, called spray, far downstream of the injector. From the modeling point of view, the emergence of Eulerian techniques for the spray description is considered promising by the scientific community. Moreover, the bottleneck issue for Eulerian methods of capturing the droplet size distribution with a reasonable computational cost, has been successfully tackled through the development of Eulerian Multi Size Moment (EMSM) method. Towards realistic ICE applications, the present PhD work addresses the modeling of two-way turbulent interactions between the polydisperse spray and its surrounding gas-phase through EMSM method. Following to the moving mesh formalism ArbitraryLagrangian Eulerian (ALE), the source terms arising in the two-phase model have been treated separately from other contributions. The equation system is closed through the maximum entropy (ME) reconstruction technique originally introduced for EMSM. A new resolution strategy is developed in order to guarantee the numerical stability under veryfast time scales related to mass, momentum and energy transfers, while preserving the realizability condition associated to the set of high order moments. From the academic point of view, both the accuracy and the stability have been deeply investigated under both constant and time dependent evaporation laws. All these developments have beenintegrated in the industrial software IFP-C3D dedicated to compressible reactive flows. In the context of 2-D injection simulations, very encouraging quantitative and qualitative results have been obtained as compared to the reference Lagrangian simulation of droplets. Moreover, simulations conducted under a typical 3-D configuration of a combustion chamber and realistic injection conditions have given rise to fruitful achievements. Within the framework of industrial turbulence modeling, a Reynolds averaged (RA) extension of the two-way coupling equations is derived, providing appropriate closures for turbulent correlations. The correct energy partitions inside the spray and turbulent interactions between phases have been demonstrated through homogeneous test-cases. The latter cases gave also some significant insights on underlying physics in ICE. This new RA approach is now ready for ICE application simulations
Vicentini, Maxime. "Mise en évidence expérimentale et modélisation des régimes de combustion diphasique présents dans les foyers aéronautiques." Thesis, Toulouse, ISAE, 2016. http://www.theses.fr/2016ESAE0011/document.
Nowadays, combustion of hydrocarbons is widespread in many engineering applications, including aeronautical propulsion. However, gas turbines produce pollutant emission levels that are no longer accepted. Therefore, understanding physical phenomena involved in combustion chambers is a major issue to help to the development of more eco-friendly engines. In aero-engine combustors, fuel is injected as a spray of droplets which generates a strong interaction with the turbulent air flow and the flame. This thesis aims at contributing to the development of two-phase combustion models to improve the predictive ability of numerical simulation tools. To do so, a new test setup dedicated to the study of two-phase turbulent flames has been designed and an experimental database has been built (non-reactive and reactive conditions). Simultaneous visualizations of Mie scattering droplets and heat release rate have highlighted a complex flame structure and the existence of different spray combustion regimes. Another important point of this work was to perform a statistical analysis of the spatial distribution of droplets under reactive conditions using an original measurement method. This analysis permitted to measure the inter-droplet distances (nearest neighbor) in different points of the flow and to assess the errors related to the processing of data through a numerical approach. It further appears that the spatial distribution of droplets is similar to an uniform random law while droplet combustion models are often based on a regular law
Cessou, Armelle. "Stabilisation de la combustion diphasique turbulente au-dessus d'un injecteur coaxial méthanol/air." Rouen, 1994. http://www.theses.fr/1994ROUES039.
Duchaine, Patrick. "Experimental analysis of the dynamics of gaseous and two-phase counterflow flames submitted to upstream modulations." Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00545418.
Linassier, Guillaume. "Étude expérimentale et numérique de l’allumage des turboréacteurs en conditions de haute altitude." Thesis, Toulouse, ISAE, 2012. http://www.theses.fr/2012ESAE0013/document.
Design of aircraft engines requires tests on engine benches. These tests allow characterizing combustor ignition limits, but are extremely expensive and time consuming. In order to limit their number, it is necessary to develop alternative methods enabling to predict the ignition performances of a combustor prototype, for both ground conditions and high altitude conditions, the latter being particularly critical.The purpose of this thesis is to contribute to the development and validation of numerical tools enabling to predict ignition performances of combustor. Validation will be possible using an experimental data base obtained on the MERCATO test bench, at ONERA. This work results from a close cooperation with TURBOMECA. A numerical model, previously developed to predict the ignition of fuel spray following a spark discharge, has been improved. This model has been combined to a multiphysics CFD code (CEDRE) in orderto build ignition map from a mean two-phase flow field, and also to compute the flame propagation stage using RANS approach. In order to validate both methods, experimental characterization of a one-sectorcombustor has been performed on the MERCATO test rig. A complete data base for validation of CFD code isnow available. Comparison of experimental and numerical ignition mapping showed good agreements for the different tests cases, and seems encouraging for an application on an industrial combustor. In the same time,promising results have been obtained with a new experimental three-sector combustor. Its geometry is basedon an industrial combustor, allowing a comparison of ignition performances between the simplified and the industrial combustors
Belerrajoul, Mohamed. "Modélisation multi-échelle de la combustion d'un nuage de particules." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0014/document.
The presence of fine particles of oxidizable materials is encountered in many industrial situations.The risk of dust explosion presents a constant threat in transformation industries that manufacture,use or manipulate powders or combustible materials dusts. In nuclear safety analysis, one of themain scenarios is the risk of graphite dust explosion that may occur during decommissioningoperations of Uranium Natural Graphite Gas reactors. The issue considered in this thesis isrelated to combustion of a dilute gas-particle mixture. This work aims at developing a macroscopicEuler-Lagrange model for predicting laminar flame velocity, which is one of the essential data forturbulent flame velocity models used to evaluate the risk of dust explosion. First, the macroscopicheat and mass transfer equations are derived using the volume averaging method. The majorinterest of the proposed approach is to provide closure problems that allow to estimate theeffective transport coefficients, such as heat exchange coefficients and the effective coefficient ofthe heterogeneous reaction. Second, Euler-Lagrange simulations are used to determine the planetwo-phase laminar flame velocity as a function of gas mixture and graphite dust characteristics.The proposed model is compared to the classical Euler-Lagrange model based on the resolutionof the boundary layer problem in the vicinity of an isolated particle in infinite medium. Results showthat the dilution rate and the indirect particle-particle exchanges are not systematically negligible inthe macroscopic exchanges between the two-phases. On the other hand, this study suggests thepotentiality of the proposed approach for detailed simulations of two-phase flow
Sporschill, Gustave. "Numerical approach of a hybrid rocket engine behaviour : Modelling the liquid oxidizer injection using a Lagrangian solver." Thesis, KTH, Mekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217231.
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.
Car 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
Pelletier, Milan. "Diffuse interface models and adapted numerical schemes for the simulation of subcritical to supercritical flows." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC059/document.
In various industrial combustion devices, such as liquid rocket engines at ignition or Diesel engines during the compression stage, the operating point varies over a wide range of pressures. These pressure variations can lead to a change of thermodynamic regime when the critical pressure is exceeded, switching from two-phase injection to transcritical injection. This change modifies the topology of the flow and the mixing, thereby impacting the flame dynamics. The objective of the present Ph.D thesis is to develop an original methodology able to address both subcritical and supercritical flows within the same solver. To achieve this, an extension of the real gas solver AVBP-RG to subcritical two-phase flows is provided, based on diffuse interface models. The required developments for the integration of such models into the finite-element framework of the solver are provided. Multidimensional numerical simulations are led in order to confront the model with experimental data, with which good agreement is observed. These results offer encouraging perspectives regarding further enhancements of the model and applications to complex industrial cases
Le, Touze Clément. "Couplage entre modèles diphasiques à « phases séparées » et à « phase dispersée » pour la simulation de l’atomisation primaire en combustion cryotechnique." Thesis, Nice, 2015. http://www.theses.fr/2015NICE4088/document.
Two-phase flows play a significant role for the proper functioning of cryogenic liquid-propellant rocketengines, such as those that equip the launchers of the Ariane family. Since the experimental investigationof such propulsion devices is complex and expensive, developing numerical tools able to accuratelysimulate their functioning, is a crucial but nonetheless ambitious objective. The major difficulty is due tothe multiscale nature of the problem, as a result of which there is currently no numerical approach ableto perfectly describe all the liquid scales on its own. Based on this observation the work presented in thisthesis aims at setting up a coupling strategy between models well-adapted to each two-phase flowtopology, in the framework of the ONERA’s multiphysics CEDRE software. The approach adoptedprecisely consists in coupling a 4-equation diffuse interface model for the separated phases and aeulerian kinetic model for the dispersed phase, thus making it possible to describe primary atomization.Besides, the harsh conditions within cryogenic rocket engines, where large temperature, velocity anddensity gradients are encountered, severely challenge the robustness of numerical methods. A newmultislope MUSCL method for general unstructured meshes is thus developed in order to improve therobustness and accuracy of space discretization schemes. The whole coupling strategy is finally appliedto the numerical simulation of the ONERA’s Mascotte test bench for cryogenic combustion research
Berat, Claude. "Contributions a la mise au point d'un programme de simulation numerique d'un four a charbon pulverise." Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0039.
Roux, Anthony. "Simulation aux Grandes Echelles d'un statoréacteur." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT025H/document.
Design of ramjets benefits today from the progress of numerical tools which relieve the various test stages of real engines that remain necessary for the development of such a kind of configuration. The objective of this dissertation is to develop a methodology based on the Large Eddy Simulation (LES) to contribute to the validation of this new type of advanced numerical tool for the simulation of ramjets and improve the understanding of combustion in these devices. The numerical tool is first adapted for the simulation of highly turbulent reacting flows with emphases on the management of shocks with centered schemes and the discretization of convection for the Eulerian simulation of the dispersed phase. The target configuration is the “Research ramjet” experimentally studied by ONERA. Simulation is carried out gradually. First, it is shown that the simulation of the entire configuration, including diffusers at the inlets where shocks appear is essential to consider an acoustically close geometry to properly reproduce the oscillation modes of combustion. The relevance of the kinetic scheme is also studied. It is shown that reproducing the evolution of the adiabatic flame speed for a wide range of equivalence ratio is critical because of the partially premixed combustion regime involved in this configuration. Finally, three different cases are simulated and excellent agreement is found with experimental data. The phenomenology and the different mechanisms governing combustion are studied for these three cases
Popoola, Olubunmi Tolulope. "Numerical, Analytical, and Experimental Studies of Reciprocating Mechanism Driven Heat Loops for High Heat Flux Cooling." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3505.
Kah, Damien. "Prise en compte des aspects polydispensés pour la modélisation d'un jet de carburant dans les moteurs à combustion interne." Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00628908/en/.
Louis, Neven. "Numerical simulations of thedecomposition of a greenpropellant." Thesis, KTH, Mekanik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-250021.
Berti, Rafael da Cruz Ribeiro. "Interaction of turbulent structures with ethanol sprays in mixture formation processes in a constant-flow chamber." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-19092018-082453/.
O estudo da formação e evolução dos sprays é essencial para o desenvolvimento de modelos físicos mais detalhados e novas estratégias de injeção para motores de combustão interna de injeção direta. No presente trabalho, os sprays de um injetor multi-furos são avaliados em um esforço para caracterizar os efeitos do desenvolvimento do spray em fluxo de ar constante. Estas interações são estudadas em termos de características de turbulência do ar,do fluxo mássico de ar e da pressão de injeção de combustível. Sprays de etanol são injetados em uma câmara de fluxo constante. O objetivo do aparato é isolar o experimento de propriedades do escoamento intrínsecas ao funcionamento de motores de combustão interna, tais como instabilidades e geometrias móveis. Os fatores que afetam as interações de arspray foram avaliados com os campos de velocidade do ar obtidos na presença de spray. A técnica de velocimetria por imagem de partículas de duas fases foi aprimorada para permitir a medição nas condições experimentais. Em todas as condições, a interação é baseada em um diferencial de pressão formado entre as regiões interna e externa do spray. Os resultados indicam um mecanismo diferente quando comparado com condições quiescentes. O vortex formado na fronteira do spray é observado apenas nos estágios iniciais de injeção. No entanto, o transiente de fim de injeção ainda está presente para essas condições. O mecanismo de interação acelera as distribuições de velocidade em direção à fronteira do jato. Os experimentos indicam que o aumento do fluxo de massa de ar modifica a velocidade de penetração do ar, mas sem alterar as características do mecanismo de interação. Distribuições de intensidade turbulenta são calculadas para o fluxo de ar durante o evento de injeção. As distribuições indicam que os sprays atenuam a intensidade turbulenta em todas as condições, consistente com as observações dos campos de velocidade. Para avaliar os efeitos da turbulência do ar, conjuntos de placas perfuradas intercambiáveis são utilizadas para limitar as escalas integrais de turbulência. As análises do espectrograma indicam que a turbulência é reduzida não apenas nas escalas integrais, mas também em todas as escalas de freqüência medidas. Estas escalas integrais de turbulência do fluxo de ar de entrada têm pouca influência no desenvolvimento do spray. No campo de turbulência, os níveis de potência ao final da injeção foram semelhantes, independentemente das escalas integrais de turbulência de entrada.
Laboureur, Delphine. "Experimental characterization and mondeling of hazards, BLEVE and BOILOVER." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209603.
The objective of this thesis is to study the apparition criteria and the consequences of an accident involving a container of pressure liquefied gas (BLEVE phenomenon) or liquid fuels (Boilover phenomenon). After a bibliographic research on the two phenomena, an experimental study in laboratory scale is conducted and from the results, the phenomena and their hazards are modeled. Small scale experiments are performed in the BABELs facility (Bleve And Boilover ExperimentaL setup) that consists of a cylindrical chamber of 2m diameter and 3m high, with round shape flanges, made out of steel with a rated pressure of 0.5 MPa. It has 3 series of 7 optical accesses, an entrance door, and an optional air venting system.
A Boilover is a violent ejection of fuel due to the vaporization of a water sublayer, resulting in an enormous fire enlargement and formation of fireball and ground fire. Small scale experiments with cylindrical reservoirs of 0.08 to 0.3m diameter in glass or metal, filled with a mixture of diesel and oil have been performed. Instrumentation of the measurements consists of thermocouples rake, Medtherm radiometers, load cell and CCD or high-speed camera with a fisheye. During the quasi-steady combustion prior the Boilover, the typical variables describing a pool fire like burning rate, flame size, puffing frequency and radiation can be predicted with semi-empirical correlations available in the literature. At Boilover onset, high speed visualizations in glass reservoir show that the growth of one big bubble leads to a boiling front that propagates radially all along the fuel-water interface, ejecting the upper fuel layer and leading to the increase of flame size. LS-PIV technique applied to high-speed camera images shows that the flame enlargement is directly linked to the velocity of the flame.
A BLEVE (or Boiling Liquid Expanding Vapour Explosion) is an explosion resulting from the catastrophic failure of a vessel containing a liquid at a temperature significantly above its boiling point at normal atmospheric pressure. Small scale experiments are performed with cylinders of 42g of propane, laid horizontally and heated from below by an electrical resistor. A groove of the reservoirs on the upper part allows better reproducibility of the rupture. High speed visualization and shadowgraphy are helping in visualizing the rupture and the content release. Thermocouples and PCB are also used to measure respectively the temperature and the blast wave overpressure. These experiments show that the fluid behavior during rupture differs with the size of the weakened part and therefore with the rupture pressure. The internal pressure measurement showed that the rupture pressure and temperature are supercritical, leading to the definition of a new type of BLEVE since there is no distinction between liquid and vapor phases prior rupture.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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.
Macé, Olivier. "Etude des champs de températures dans des écoulements hétérogènes : applications aux flammes de charbon pulverisé et aux lits fluidisés circulants." Rouen, 1989. http://www.theses.fr/1989ROUES032.
Yang, Songzhi. "Modeling of Diesel injection in subcritical and supercritical conditions." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC045/document.
To satisfy latest stringent emission regulations, important progress is still be expected from internal combustion engines. In addition, improving engine efficiency to reduce the emission and fuel consumption has become more essential than before. But many complex phenomena remain poorly understood in this field, such as the fuel injection process. Numerous software programs for computational fluid dynamics (CFD) considering phase change (such as cavitation) and injection modelling, have been developed and used successfully in the injection process. Nevertheless, there are few CFD codes able to simulate correctly transcritical conditions starting from a subcritical fuel temperature condition towards a supercritical mixture in the combustion chamber. Indeed, most of the existing models can simulate either single-phase flows possibly in supercritical condition or two-phase flows in subcritical condition; lacking therefore, a comprehensive model which can deal with transcritical condition including possible phase transition from subcritical to supercritical regimes, or from single-phase to two-phase flows, dynamically. This thesis aims at dealing with this challenge. For that, real fluid compressible two-phase flow models based on Eulerian-Eulerian approach with the consideration of phase equilibrium have been developed and discussed in the present work. More precisely, a fully compressible 6-equation model including liquid and gas phases balance equations solved separately; and a 4-equation model which solves the liquid and gas balance equations in mechanical and thermal equilibrium, are proposed in this manuscript. The Peng-Robinson equation of state (EoS) is selected to close both systems and to deal with the eventual phase change or phase transition. Particularly, a phase equilibrium solver has been developed and validated. Then, a series of 1D academic tests involving the evaporation and condensation phenomena performed under subcritical and supercritical conditions have been simulated and compared with available literature data and analytical results. Then the fully compressible two-phase flow models (6-Equation and 4-Equation systems) have been employed to simulate the cavitation phenomena in a real size 3D nozzle to investigate the effect of dissolved N2 on the inception and developing of cavitation. The good agreement with experimental data proves the solver can handle the complex phase change behavior in subcritical condition. Finally, the capability of the solver in dealing with the transcritical injection at high pressure and temperature conditions has been further validated through the successful modelling of the engine combustion network (ECN) Spray A injector
Deng, Tian. "LES combined with statistical models of spray formation closely to air-blast atomizer." Thesis, Ecully, Ecole centrale de Lyon, 2011. http://www.theses.fr/2011ECDL0037/document.
This thesis introduced an extension to stochastic approach for simulation of air-blast atomization closely to injector. This approach was previously proposed in publications of Gorokhovski with his PHD students. Our extension of this approach is as follows. In the framework of LES approach, the contribution of primary atomization zone is simulated as an immersed solid body with stochastic structure. The last one is defined by stochastic simulation of position-and-curvature of interface between the liquid and the gas. As it was done previously in this approach, the simulation of the interface position was based on statistical universalities of fragmentation under scaling symmetry. Additionally to this, we simulate the outwards normal to the interface, assuming its stochastic relaxation to isotropy along with propagation of spray in the down-stream direction. In this approach, the statistics of immersed body force plays role of boundary condition for LES velocity field, as well as for production of primary blobs, which are then tracked in the Lagrangian way. In this thesis, the inter-particle collisions in the primary atomisation zone are accounted also by analogy with standard kinetic approach for the ideal gas. The closure is proposed for the statistical temperature of droplets. The approach was assessed by comparison with measurements of Hong in his PHD. The results of computation showed that predicted statistics of the velocity and of the size in the spray at different distances from the center plane, at different distances from the nozzle orifice, at different inlet conditions (different gas velocity at constant gas-to-liquid momentum ratio, different gas-to-liquid momentum ratio) are relatively close to measurements. Besides, the specific role of recirculation zone in front of the liquid core was emphasized in the flapping of the liquid core and in the droplets production
Kunda, Wilkinson. "Two phase problems and two phase flow." Thesis, University of Hull, 1986. http://hydra.hull.ac.uk/resources/hull:5902.
Cordesse, Pierre. "Contribution to the study of combustion instabilities in cryotechnic rocket engines : coupling diffuse interface models with kinetic-based moment methods for primary atomization simulations." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC016.
Gatekeepers to the open space, launchers are subject to intense and competitive enhancements, through experimental and numerical test campaigns. Predictive numerical simulations have become mandatory to increase our understanding of the physics. Adjustable, they provide early-stage optimization processes, in particular of the combustion chamber, to guaranty safety and maximize efficiency. One of the major physical phenomenon involved in the combustion of the fuel and oxidizer is the jet atomization, which pilotes both the droplet distributions and the potential high-frequency instabilities in subcritical conditions. It encompasses a large sprectrum of two-phase flow topologies, from separated phases to disperse phase, with a mixed region where the small scale physics and topology of the flow are very complex. Reduced-order models are good candidates to perform predictive but low CPU demanding simulations on industrial configurations but have only been able so far to capture large scale dynamics and have to be coupled to disperse phase models through adjustable and weakly reliable parameters in order to predict spray formation. Improving the hierarchy of reduced order models in order to better describe both the mixed region and the disperse region requires a series of building blocks at the heart of the present work and give on to complex problems in the mathematical analysis and physical modelling of these systems of PDE as well as their numerical discretization and implementation in CFD codes for industrial uses. Thanks to the extension of the theory on supplementary conservative equations to system of non-conservation laws and the formalism of the multi-fluid thermodynamics accounting for non-ideal effects, we give some new leads to define a strictly convex mixture entropy consistent with the system of equations and the pressure laws, which would allow to recover the entropic symmetrization of two-phase flow models, prove their hyperbolicity and obtain generalized source terms. Furthermore, we have departed from a geometric approach of the interface and proposed a multi-scale rendering of the interface to describe multi-fluid flow with complex interface dynamics. The Stationary Action Principle has returned a single velocity two-phase flow model coupling large and small scales of the flow. We then have developed a splitting strategy based on a Finite Volume discretization and have implemented the new model in the industrial CFD software CEDRE of ONERA to proceed to a numerical verification. Finally, we have constituted and investigated a first building block of a hierarchy of test-cases designed to be amenable to DNS while close enough to industrial configurations in order to assess the simulation results of the new model but also to any up-coming models
Ariyoshi, Gen. "Flow Characteristics of Lead-Bismuth Two-phase Flow." Kyoto University, 2019. http://hdl.handle.net/2433/242325.
Desclaux, Anthony. "Etude expérimentale du comportement linéaire et non linéaire d’une flamme diphasique soumise à une excitation acoustique. Mise en œuvre d’une méthode de contrôle adaptative." Thesis, Toulouse, ISAE, 2020. http://depozit.isae.fr/theses/2020/2020_Desclaux_Anthony_D.pdf.
This PhD thesis supports the effort undertaken by ONERA to understand the mechanisms of stabilizationof two-phase flames in aeronautical engines. This work concerns more particularly the dynamics of spraysand flames disturbed by acoustic waves. This work studies the role of liquid fuel injection on the non-linearresponse of stabilized flames downstream of an industrial multipoint injector with a central pilot zone. Basedon previous work, the first objective is to study the influence of acoustic disturbances on the behavior ofliquid fuel injection in the multipoint zone. The observed phenomena are reproduced, in an idealized form,from a simplified experimental set up based on the configuration of a liquid jet injected into air crossflowsubmitted to an acoustic forcing. The results highlight the atomization mechanisms of the jet and itsinteraction with acoustic disturbances. The study of the spray shows the appearance of droplet densitywaves. The influence of drop size on these phenomena is characterized. The second objective of this workis to analyze the behavior of a two-phase flame (kerosene/air) disturbed by acoustic excitations. In this case,a second experimental configuration is implemented. This experimental set up reproduces in a realistic waythe phenomena encountered in combustion chambers. This work uses the "Flame Describing Function"(FDF) approach. In order to do this, the fluctuations of the heat release rate from the flame are characterizedusing an original method based on the simultaneous measurement of the chemiluminescence of severalradicals. The results are obtained for two injection configurations, one using the pilot zone alone and theother using the entire injector. The analysis of the FDFs reveals saturation phenomena which limit the flameresponse. Comparison of the results between the two injection configurations shows that the delay betweenflame response and flow disturbances is strongly influenced by the injection mode. All the results obtainedin this work constitute an experimental database to validate reactive LES simulations and to provide a modelfor describing the flame behavior in simulations based on "low order" approaches
Neuweiler, Insa. "Macroscopic parameters for two-phase flow." [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13490.
Dillon, Chad Michael. "Two-Phase Flow Within Narrow Annuli." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5097.
Srichai, Somprasong. "High pressure separated two-phase flow." Thesis, Imperial College London, 1994. http://hdl.handle.net/10044/1/8656.
Sharma, Yugdutt. "Modeling transient two-phase slug flow /." Access abstract and link to full text, 1985. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/8605319.
Lillibridge, Kris Hamilton. "Buoyancy-driven two-phase countercurrent flow." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/16027.
McQuillan, K. W. "Flooding in annular two-phase flow." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354843.
Willetts, I. P. "Non-aqueous annular two-phase flow." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393120.
Klidonas, G. "Void fraction in two phase flow." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235032.
Stewart, Colin. "Metering of two-phase slug flow." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21158.
Roberts, Paul Anthony. "Two-phase flow at T-junctions." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240490.