Gotowe bibliografie tematyczne / Flame Particle Tracking

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Gotowa bibliografia na temat „Flame Particle Tracking”

Autor: Grafiati

Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "Flame Particle Tracking"

Xie, Qing, Siheng Yang, Hao Cheng, Chi Zhang i Zhuyin Ren. "Predicting the ignition sequences in a separated stratified swirling spray flame with stochastic flame particle tracking". Journal of the Global Power and Propulsion Society 6 (12.10.2022): 279–89. http://dx.doi.org/10.33737/jgpps/153495.

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Stochastic flame particle tracking in conjunction with non-reacting combustor simulations can offer insights into the ignition processes and facilitate the combustor optimization. In this study, this approach is employed to simulate the ignition sequences in a separated dual-swirl spray flame, in which the newly proposed pairwise mixing-reaction model is used to account for the mass and energy transfer between the flame particle and the surrounding shell layer. Based on the flame particle temperature, the particle state can be classified in to burnt, hot gas, and extinguished. The additional state of hot gas is introduced to allow the flame particles with high temperature to survive from nonflammable region and then potentially to ignite the nearby favourable regions. The simulations of the separated stratified swirl spray flame reveal two different ignition pathways for flame stabilization. The first showed that some flame particles from the spark would directly enter the main recirculation zone resulting from the velocity randomness and then ignite both sides of the combustor simultaneously. The second showed that flame particles from the spark would ignite the traversed regions following the swirl motion inside the combustor. The predicted ignition sequences were compared with the evolution of flame morphology recorded by high-speed imaging from experiments, showing qualitative agreement.

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Echekki, T., i M. G. Mungal. "Particle Tracking in a Laminar Premixed Flame". Physics of Fluids A: Fluid Dynamics 2, nr 9 (wrzesień 1990): 1523. http://dx.doi.org/10.1063/1.4738844.

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Uranakara, Harshavardhana A., Swetaprovo Chaudhuri, Himanshu L. Dave, Paul G. Arias i Hong G. Im. "A flame particle tracking analysis of turbulence–chemistry interaction in hydrogen–air premixed flames". Combustion and Flame 163 (styczeń 2016): 220–40. http://dx.doi.org/10.1016/j.combustflame.2015.09.033.

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Weber, R., A. A. F. Peters, P. P. Breithaupt i B. M. Visser. "Mathematical Modeling of Swirling Flames of Pulverized Coal: What Can Combustion Engineers Expect From Modeling?" Journal of Fluids Engineering 117, nr 2 (1.06.1995): 289–97. http://dx.doi.org/10.1115/1.2817143.

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The present study is concerned with mathematical modeling of swirling pulverized coal flames. The attention is focused on the near burner zone properties of high-and low-NOx flames issued from an Aerodynamically Air Staged Burner of 3.4 MW thermal input. The swirling combusting flows are calculated using the k–ε model and second-order models of turbulence. The Eulerian balance equations for enthalpy and mass fractions of oxygen, volatiles, carbon monoxide and final combustion products (CO2 + H2O) are solved. The Lagrangian particle tracking is accompanied by appropriate models of coal devolatilization and char combustion. Nitric oxide emissions are calculated using a NOx post-processor for thermal-, prompt- and fuel-NO. The objective of this paper is to examine whether the engineering information required for designing industrial burners is obtainable through the mathematical modeling. To this end, the flame computations, including NO emissions, are compared with the measured in-flame data. The guidelines as to the combination of physical submodels and model parameters needed for quality predictions of different flame types are given. The paper is a shorter version of our recent ASME publication (Weber et al., 1993).

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XIE, Qing, Zhuyin REN i Ke WANG. "Modelling ignition probability with pairwise mixing-reaction model for flame particle tracking". Chinese Journal of Aeronautics 34, nr 5 (maj 2021): 523–34. http://dx.doi.org/10.1016/j.cja.2020.12.031.

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Lee, K. H., i C. S. Lee. "Effects of tumble and swirl flows on turbulence scale near top dead centre in a four-valve spark ignition engine". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 217, nr 7 (1.07.2003): 607–15. http://dx.doi.org/10.1243/095440703322114988.

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The in-cylinder flowfield and the turbulence scale at the ignition timing play an important role in enhancing the propagation speed of the initial flame and the engine combustion. The aim of this work is to investigate the effect of tumble and swirl flows on the turbulence scale near the top dead centre in a four-valve spark ignition (SI) engine by an experimental method. In this study, various flowfields such as tumble and swirl flows were generated by intake flow control valves. For investigation of the flowfields, the single-frame particle tracking velocimeter (PTV) and the twocolour particle image velocimeter (PIV) techniques were developed to clarify the in-cylinder flow pattern during the intake stroke and the turbulence intensity near the spark plug during the compression stroke respectively. In addition, the flame propagation was visualized by an ICCD camera, and its images were analysed to compare the flowfields. From these experimental results, the effects of tumble and swirl flows on the turbulence scale and the flame propagation speed were clarified.

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Lewis, G. S., i B. J. Cantwell. "Instantaneous Two-Dimensional Velocity Field Measurements in a Periodic Flame Using Particle Tracking Velocimetry". Physics of Fluids 31, nr 9 (wrzesień 1988): 2388. http://dx.doi.org/10.1063/1.4738823.

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Liu, Kan, i David Liu. "Particle tracking velocimetry and flame front detection techniques on commercial aircraft debris striking events". Journal of Visualization 22, nr 4 (2.07.2019): 783–94. http://dx.doi.org/10.1007/s12650-019-00571-8.

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Rezk, Hegazy, Magdy M. Zaky, Mohemmed Alhaider i Mohamed A. Tolba. "Robust Fractional MPPT-Based Moth-Flame Optimization Algorithm for Thermoelectric Generation Applications". Energies 15, nr 23 (23.11.2022): 8836. http://dx.doi.org/10.3390/en15238836.

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Depending on the temperature difference between the hot and cold sides of the thermoelectric generator (TEG), the output performance of the TEG can be produced. This means that it is necessary to force a TEG based on robust maximum power point tracking (MPPT) to operate close to its MPP at any given temperature or load. In this paper, an improved fractional MPPT (IFMPPT) is proposed in order to increase the amount of energy that can be harvested from TEGs. According to the suggested method, fractional order control is used. A moth-flame optimizer (MFO) was used to determine IFMPPT’s optimal parameters. A comparison of the results obtained by the MFO is made with those obtained by a particle swarm optimizer, genetic algorithm, gray wolf optimizer, seagull optimization algorithm, and tunicate swarm algorithm in order to demonstrate MFO’s superiority. IFMPPT’s primary objective is to enhance dynamic responses and exclude steady-state oscillations. Consequently, incremental resistance and perturb and observe are compared with the proposed strategy’s performance. It was revealed that IFMPPT provides superior tracking results both in dynamic and steady-state conditions when compared with traditional methods.

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Fuyuto, Takayuki, Yoshiaki Hattori, Hayato Yamashita, Naoki Toda i Makoto Mashida. "Set-off length reduction by backward flow of hot burned gas surrounding high-pressure diesel spray flame from multi-hole nozzle". International Journal of Engine Research 18, nr 3 (28.07.2016): 173–94. http://dx.doi.org/10.1177/1468087416640429.

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The backward flow of the hot burned gas surrounding a diesel flame was found to be one of the factors reducing the set-off length (also called the lift-off length), that is, the distance from a nozzle exit into which a diffusion flame cannot intrude. In the combustion chamber of an actual diesel engine, the entrainment of the surrounding gas into a spray jet injected from a multi-hole nozzle is restricted by the combustion chamber walls and the adjacent spray jets, thus inducing the backward flow of the surrounding gas toward the nozzle exit. The emergence of this backward flow was measured by particle tracking velocimetry in the non-combusting condition. A new momentum theory for calculating the backward flow velocity was established by extending Wakuri’s momentum theory. Shadowgraph imaging in an optical engine successfully visualized the backward flow of the hot burned gas. The hot burned gas is re-entrained into the spray jet in the region of the set-off position and shortens the set-off length in comparison to that of a single free-spray flame which does not induce the backward flow.

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Rozprawy doktorskie na temat "Flame Particle Tracking"

Arimboor, Chinnan Jacob. "Simulation and validation of in-cylinder combustion for a heavy-duty Otto gas engine using 3D-CFD technique". Thesis, KTH, Förbränningsmotorteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-245172.

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Utsläpp från bilar har spelat stor roll de senaste decennierna. Detta har lett till ökad användning av Otto gasmotorer som använder naturgas som bränsle. Nya motordesigner behöver optimeras för att förbättra motorens effektivitet. Ett effektivt sätt att göra detta på är genom användningen av simuleringar för att minska ledtiden i motorutvecklingen. Verifiering och validering av simuleringarna spelar stor roll för att bygga förtroende för och förutsägbarhet hos simuleringsresultaten. Syftet med detta examensarbete är att föreslå förbränningsmodellparametrarna efter utvärdering av olika kombinationer av förbrännings- och tändmodeller för Otto förbränning, vad gäller beräkningstid och noggrannhet. In-cylindertrycksspår från simulering och mätning jämförs för att hitta den bästa kombinationen av förbrännings- och tändmodell. Inverkan av tändtid, antal motorcykler och randvillkor för simuleringsresultatet studeras också. Resultaten visar att ECFM-förbränningsmodellen förutsäger simuleringsresultaten mer exakt när man jämför med mätningarna. Effekten av tändningstiden på olika kombinationer av förbrännings- och tändningsmodell utvärderas också. Stabiliteten hos olika förbränningssimuleringsmodeller diskuteras också under körning för fler motorcykler. Jämförelse av beräkningstid görs även för olika kombinationer av förbrännings- och tändmodeller. Resultaten visar också att flamspårningsmetoden med Euler är mer känslig för cellstorlek och kvalitet hos simuleringsnätet, jämfört med övriga studerade modeller. Rekommendationer och förslag ges om nät- och simulerings-inställningar för att prediktera förbränningen på ett så bra sätt som möjligt. Några möjliga förbättringsområden ges som framtida arbete för att förbättra noggrannheten i simuleringsresultaten.
Emission from automobiles has been gaining importance for past few decades. This has gained a lot of impetus in search for alternate fuels among the automotive manufacturers. This led to the increase usage of Otto gas engine which uses natural gas as fuel. New engine designs have to be optimized for improving the engine efficiency. This led to usage of virtual simulations for reducing the lead time in the engine development. The verification and validation of actual phenomenon in the virtual simulations with respect to the physical measurements was quite important. The aim of this master thesis is to suggest the combustion model parameters after evaluating various combination of combustion and ignition models in terms of computational time and accuracy. In-cylinder pressure trace from the simulation is compared with the measurement in order to find the nest suited combination of combustion and ignition models. The influence of ignition timing, number of engine cycles and boundary conditions on the simulation results are also studied. Results showed that ECFM combustion model predicts the simulation results more accurately when compare to the measurements. Impact of ignition timing on various combination of combustion and ignition model is also assessed. Stability of various combustion simulation models is also discussed while running for more engine cycles. Comparison of computational time is also made for various combination of combustion and ignition models. Results also showed that the flame tracking method using Euler is dependent on the mesh resolution and the mesh quality. Recommendations and suggestions are given about the mesh and simulation settings for predicting the combustion simulation accurately. Some possible areas of improvement are given as future work for improving the accuracy of the simulation results.

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Winter, Henry deGraffenried III. "Combining hydrodynamic modeling with nonthermal test particle tracking to improve flare simulations". Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/winter/WinterH0509.pdf.

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Solar flares remain a subject of intense study in the solar physics community. These huge releases of energy on the Sun have direct consequences for humans on Earth and in space. The processes that impart tremendous amounts of energy are not well understood. In order to test theoretical models of flare formation and evolution, state of the art, numerical codes must be created that can accurately simulate the wide range of electromagnetic radiation emitted by flares. A direct comparison of simulated radiation to increasingly detailed observations will allow scientists to test the validity of theoretical models. To accomplish this task, numerical codes were developed that can simulate both the thermal and nonthermal components of a flaring plasma, their interactions, and their emissions. The HYLOOP code combines a hydrodynamic equation solver with a nonthermal particle tracking code in order to simulate the thermal and nonthermal aspects of a flare. A solar flare was simulated using this new code with a static atmosphere and with a dynamic atmosphere, to illustrate the importance of considering hydrodynamic effects on nonthermal beam evolution. The importance of density gradients in the evolution of nonthermal electron beams was investigated by studying their effects in isolation. The importance of the initial pitch-angle cosine distribution to flare dynamics was investigated. Emission in XRT filters were calculated and analyzed to see if there were soft X-ray signatures that could give clues to the nonthermal particle distributions. Finally the HXR source motions that appeared in the simulations were compared to real observations of this phenomena.

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Winter, Henry deGraffenried. "Combining hydrodynamic modeling with nonthermal test particle tracking to improve flare simulations". 2009. http://etd.lib.montana.edu/etd/2009/winter/WinterH0509.pdf.

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Części książek na temat "Flame Particle Tracking"

Hatwar, Madwaraj, Ashwin S. Nayak, Himanshu L. Dave, Utkarsh Aggarwal i Swetaprovo Chaudhuri. "Cluster Analysis of Turbulent Premixed Combustion Using On-the-fly Flame Particle Tracking". W Sustainable Development for Energy, Power, and Propulsion, 389–413. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5667-8_15.

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Heyman, J., i C. Ancey. "Tracking bed load particles in a steep flume: Methods and results". W River Flow 2014, 909–16. CRC Press, 2014. http://dx.doi.org/10.1201/b17133-123.

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Streszczenia konferencji na temat "Flame Particle Tracking"

Liu, Kan, David Liu i Andrew Wang. "Two-dimensional Particle Tracking Velocimetry and Flame Front Detection". W 2018 AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2018. http://dx.doi.org/10.2514/6.2018-0490.

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Uranakar, Harshavardhana A., Swetaprovo Chaudhuri i K. N. Lakshmisha. "Turbulence-Transport-Chemistry Interaction in Statistically Planar Premixed Flames and Ignition Kernels in Near Isotropic Turbulence". W ASME 2014 Gas Turbine India Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gtindia2014-8340.

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Turbulence-transport-chemistry interaction plays a crucial role on the flame surface geometry, local and global reaction-rates, and therefore, on the propagation and extinction characteristics of intensely turbulent, premixed flames encountered in LPP gas-turbine combustors. The aim of the present work is to understand these interaction effects on the flame surface annihilation and extinction of lean premixed flames, interacting with near isotropic turbulence. As an example case, lean premixed H2-air mixture is considered so as to enable inclusion of detailed chemistry effects in Direct Numerical Simulations (DNS). The work is carried out in two phases namely, statistically planar flames and ignition kernel, both interacting with near isotropic turbulence, using the recently proposed Flame Particle Tracking (FPT) technique. Flame particles are surface points residing and commoving with an iso-scalar surface within a premixed flame. Tracking flame particles allows us to study the evolution of propagating surface locations uniquely identified with time. In this work, using DNS and FPT we study the flame speed, reaction rate and transport histories of such flame particles residing on iso-scalar surfaces. An analytical expression for the local displacement flame speed (Sd) is derived, and the contribution of transport and chemistry on the displacement flame speed is identified. An examination of the results of the planar case leads to a conclusion that the cause of variation in Sd may be attributed to the effects of turbulent transport and heat release rate. In the second phase of this work, the sustenance of an ignition kernel is examined in light of the S-curve. A newly proposed Damköhler number accounting for local turbulent transport and reaction rates is found to explain either the sustenance or otherwise propagation of flame kernels in near isotropic turbulence.

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Dongmo, E., R. Gadow i M. Wenzelburger. "A Numerical Model for Combustion and Expansion in HVOF Flame Spraying". W ITSC2008, redaktorzy B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima i G. Montavon. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2008. http://dx.doi.org/10.31399/asm.cp.itsc2008p1345.

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Abstract Nano structured coatings applied by supersonic flame spray processes show a better bonding mechanism, superior hardness and better wear resistance compared to coatings with micron scale structure. However, handling and particle feeding of smaller scale (< 20µm) spray powders is difficult due to their large surface area and easy agglomeration, but also health risks. Therefore, nano structured oxide ceramic powders are mixed with organic solvents in order to form liquid suspensions that are suitable to improve the particle feeding properties. Recent attempts to understand the momentum and heat transfer mechanisms between flame and particles in HVOF flame spraying led to measurement of the in-flight particle properties and computational modeling of the processes. In this work, modeling and simulation of the HVOF spraying process as a two phase model is applied in order to analyze thermal and mass flow processes for an optimization of the spray particle properties and the final properties of the coatings themselves. Simulation results are given for particle tracking during the spray process. Thereby, particle properties are sensitive to a large number of process parameters as well as the particle diameter. Numerical results are validated by experimental diagnosis of particle properties with the SprayWatch system and by the analysis of experimental coatings.

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Frolov, S. M., i V. S. Ivanov. "Numerical simulation of deflagration-to-detonation transition by coupled flame tracking - particle method". W Progress in Propulsion Physics. Les Ulis, France: EDP Sciences, 2011. http://dx.doi.org/10.1051/eucass/201102533.

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Ermolaev, G. V., i A. V. Zaitsev. "IGNITION CONDITIONS OF A SINGLE BORON PARTICLE IN HOT GAS FLOW". W 8TH INTERNATIONAL SYMPOSIUM ON NONEQUILIBRIUM PROCESSES, PLASMA, COMBUSTION, AND ATMOSPHERIC PHENOMENA. TORUS PRESS, 2020. http://dx.doi.org/10.30826/nepcap2018-2-08.

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The basic experimental studies on boron combustion are done with the same general scheme of the experiment. Boron particles are injected into flat-flame burner products with the help of the transporting jet of cold nitrogen. Boron particle combustion process is registered with a number of optical methods. It is proposed that boron particle is injected into the main hot gas flow instantly, combustion takes place at the flame temperature and predefined oxygen concentration, and the influence of the transporting cold nitrogen jet is ignored. Recent combustion models are based mostly on this type of experiments and characterized with high complexity and low prediction level. In our study, we reconstruct the particle injection conditions for several basic experimental papers. It is shown that in all experimental setups, ignition, combustion, and even total particle burnout take place in the wake of the cold nitrogen jet. This zone is characterized with a much lower gas temperature and oxygen concentration than the main flat burner flow. The total temperature decrease can be about several hundred degrees, oxygen concentration can be 30%-50% lower than that used in the previous analysis of the experimental results. The temperatures of ignition and transition to the second stage of combustion are found with the help of the test particle trajectory and temperature tracking. It is shown that analysis of the influence of boron particles injection on gas temperature and oxygen concentration is mandatory for the development of future combustion models.

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Versailles, Philippe, Antoine Durocher, Gilles Bourque i Jeffrey M. Bergthorson. "Measurements of the Reactivity of Premixed, Stagnation, Methane-Air Flames at Gas Turbine Relevant Pressures". W ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-77018.

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The adiabatic, unstrained, laminar flame speed, SL, is a fundamental combustion property, and a premier target for the development and validation of thermochemical mechanisms. It is one of the leading parameters determining the turbulent flame speed, the flame position in burners and combustors, and the occurrence of transient processes, such as flashback and blowout. At pressures relevant to gas turbine engines, SL is generally extracted from the continuous expansion of a spherical reaction front in a combustion bomb. However, independent measurements obtained in different types of apparatuses are required to fully constrain thermochemical mechanisms. Here, a jet-wall, stagnation burner designed for operation at gas turbine relevant conditions is presented, and used to assess the reactivity of premixed, lean-to-rich, methane-air flames at pressures up to 16 atm. One-dimensional (1D) profiles of axial velocity are obtained on the centreline axis of the jet-wall burner using Particle Tracking Velocimetry, and compared to quasi-1D flame simulations performed with a selection of thermochemical mechanisms available in the literature. Significant discrepancies are observed between the numerical and experimental data, and among the predictions of the mechanisms. This motivates further chemical modeling efforts, and implies that designers in industry must carefully select the mechanisms employed for the development of gas turbine combustors.

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Puduppakkam, Karthik V., Abhijit U. Modak, Chitralkumar V. Naik, Joaquin Camacho, Hai Wang i Ellen Meeks. "A Soot Chemistry Model That Captures Fuel Effects". W ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-27123.

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A detailed chemistry model is necessary to simulate the effects of variations in fuel composition on soot emissions. In this work, we have developed a detailed chemistry model for the soot formation and oxidation chemistry, with a focus on the surface kinetics of the soot-particle. The model has been compared to a unique set of soot particle-size data measured in flames for several single-component fuels. Fuel components used in the experiments represent the chemical classes found in jet, gasoline, and diesel fuels, including n-heptane (representative of n-alkanes) and toluene (aromatic). Measurements were taken in burner-stabilized stagnation-flame (BSSF) experiments, which can be simulated well using the 1-dimensional BSSF flame model in CHEMKIN-PRO. Soot volume fraction and particle size distributions are modeled using the sectional method option for Particle Tracking, within CHEMKIN-PRO software. The well-characterized flow of the BSSF experiments allows the modeling to focus on the kinetics. Validated detailed reaction mechanisms for fuel combustion and PAH production, combined with the new soot surface-kinetics mechanism, were used in the simulations. Simulation results were compared to measurements for both particle size distributions and total soot volume fraction. Observed effects of fuel, temperature, pressure, equivalence ratio and residence time on the soot size distribution shape and soot quantity were reproduced by the model. The chemistry in the soot surface model includes particle nucleation, growth through the HACA (hydrogen-abstraction/carbon-addition) and PAH-condensation (polycyclic aromatic hydrocarbons) pathways, as well as soot-oxidation pathways. In addition to soot chemistry, the physics of particle coagulation and aggregation were included in the model. The results demonstrate the ability of well-validated chemistry to predict both dramatic and subtle effects related to soot mass and soot particle size.

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Boyde, J. M., P. Le Clercq, M. Di Domenico, M. Rachner, G. C. Gebel, T. Mosbach i M. Aigner. "Validation of an Ignition and Flame Propagation Model for Multiphase Flows". W ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45104.

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This paper presents a numerical investigation of a generic lab scale combustor with focus on the ignition characteristics. The test case has been examined thoroughly in a comprehensive measurement campaign to provide a detailed set of boundary conditions and a profound data base of results. The experimental setup comprises five parallel-aligned mono-disperse droplet chains which are ignited, using a focused laser beam. One aspect of the experimental study is the ignitability with respect to the imposed boundary conditions. The second covers the growth and the propagation of the flame after the establishment of an initial kernel. The outcome of the numerical simulations is compared to the experimental results which allows an in-depth assessment of the employed numerical models. The chemistry and, thus, the flame propagation behavior is captured by a turbulent flame speed closure approach with an adaptation to render the model suitable to multiphase flows. For the dispersed phase a Lagrangian particle tracking scheme is employed in combination with a continuous thermodynamics fuel model for the evaporation. The overall good agreement demonstrates the capability of a multiphase flow CFD solver in the field of ignition modeling.

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Munzar, Jeffrey D., Ahmed Zia, Philippe Versailles, Rodrigo Jiménez, Jeffrey M. Bergthorson i Benjamin Akih-Kumgeh. "Comparison of Laminar Flame Speeds, Extinction Stretch Rates and Vapor Pressures of Jet A-1/HRJ Biojet Fuel Blends". W ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25951.

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An emerging goal within the aviation industry is to replace conventional jet fuel with biologically-derived alternative fuel sources. However, the combustion properties of these potential fuels must be thoroughly characterized before they can be considered as replacements in turbomachinery applications. In this study, seven candidate alternative fuel blends, derived from two biological feedstocks and blended in different quantities with Jet A-1, are considered. For each blend, the laminar flame speed, non-premixed extinction stretch rate, and vapor pressure are experimentally determined and compared to numerical simulations and to Jet A-1 data. Hydrodynamically-stretched flame speeds are determined by applying particle image velocimetry (PIV) to an atmospheric pressure, preheated jet-wall stagnation flame, and the unstretched laminar flame speed is inferred using a direct comparison method in conjunction with a binary jet-fuel surrogate, with results spanning a wide equivalence ratio range. Extinction stretch rates were measured using particle tracking velocimetry (PTV) in a non-premixed counterflow diffusion flame, over a range of fuel mass fractions diluted in nitrogen carrier gas. Finally, the vapor pressure of the seven biojet/Jet A-1 fuel blends was measured using an isoteniscope over a wide temperature range. The results of this study indicate that moderate blends of hydrotreated renewable jet (HRJ) fuel with Jet A-1 have similar combustion properties to conventional jet fuel, highlighting their suitability as drop-in replacements, while higher blend levels of HRJ fuel, regardless of the crop source, lead to definitive changes in the combustion parameters investigated here.

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Chong, Shao Teng, Venkat Raman, Michael E. Mueller i Hong G. Im. "The Role of Recirculation Zones in Soot Formation in Aircraft Combustors". W ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76217.

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Recirculation zone plays an important role in flame stabilization in combustors and gas turbines. The location, size, and strength of recirculation zones are important features of a combustor. However, the quantitative role of recirculation zones in affecting soot formation from an aero combustor is not fully understood. In a turbulent flow field with swirling flows and high frequency oscillations of the inflow jets, inner recirculation zones and outer recirculation zones have different functions in determining soot evolution. In this study, large-eddy simulation (LES) of soot formation with detailed physical and chemical models is used in order to study the dynamic aspects of soot formation. The soot population is modeled using the hybrid method of moments (HMOM), while the gas phase precursor evolution is modeled using detailed chemical kinetics. A model aero combustor, studied experimentally at DLR, is used as the baseline flow configuration. The simulations are used to understand the transport of soot particles within such complex flows. In particular, the ability of recirculation regions to increase soot formation by increasing residence times is explored. A Lagrangian particle tracking (LPT) analysis is carried out and statistical roles of recirculation zones are determined from these streamlines. Furthermore, source term analysis of these particles are performed to determine the key physical processes that contribute to soot mass in the recirculation zones. From a numerical stand-point, such soot evolution introduces limitations for statistical convergence, which will also be discussed. In particular, a time-scale analysis will be conducted to determine total computational time needed to obtain converged soot statistics.

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