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Готові списки джерел за темами / Reactive premixted flow

Добірка наукової літератури з теми "Reactive premixted flow"

Автор: Grafiati

Опубліковано: 7 липня 2024

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Статті в журналах з теми "Reactive premixted flow":

1

Porumbel, Ionuţ, Andreea Cristina Petcu, Florin Gabriel Florean, and Constantin Eusebiu Hritcu. "Artificial Neural Networks for Modeling of Chemical Source Terms in CFD Simulations of Turbulent Reactive Flows." Applied Mechanics and Materials 555 (June 2014): 395–400. http://dx.doi.org/10.4028/www.scientific.net/amm.555.395.

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The main goal of the work presented here was to develop, implement and test a highly efficient numerical algorithm for the evaluation of the chemical reaction source terms that appear in the Navier - Stokes equations when a turbulent, premixed, reactive flow is simulated using a finite rate chemistry combustion model. The approach was based on employing Artificial Neural Networks (ANN) that were designed, trained and incorporated into an existing LEM – LES numerical algorithm. Two numerical simulations of reacting flows have been carried out using several techniques for the estimation of the LES filtered reaction rate for the chemical species in laminar and turbulent, premixed, reactive flows, and the results were compared in terms of numerical accuracy and computational speed. It was concluded that the ANN approach provides a significant speedup of the numerical simulation while preserving acceptable accuracy.

2

KIM, SEUNG HYUN, and ROBERT W. BILGER. "Iso-surface mass flow density and its implications for turbulent mixing and combustion." Journal of Fluid Mechanics 590 (October 15, 2007): 381–409. http://dx.doi.org/10.1017/s0022112007008117.

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A new result is derived for the mass flow rate per unit volume through a scalar iso-surface – called here the ‘iso-surface mass flow density’. The relationship of the surface mass flow density to the local entrainment rate per unit volume in scalar mixing and to the local reaction rate in turbulent premixed combustion is considered. In inhomogeneous flows, integration of the surface mass flow density across the layer in the direction of the mean scalar inhomogeneity yields the mean entrainment velocity in scalar mixing and the turbulent burning velocity in premixed combustion. For non-premixed turbulent reacting flow, this new result is shown to be consistent with the classical result of Bilger (Combust. Sci. Technol. vol. 13, 1976, p. 155) for fast one-step irreversible chemical reactions. Direct numerical simulation data for conserved scalar mixing, isothermal reaction front propagation and turbulent premixed flames are analysed. It is found that the entrainment velocity in the conserved scalar mixing case is sensitive to a threshold value. This suggests that the entrainment velocity is not a well-defined concept in temporally developing mixing layers and that scaling laws for the viscous superlayer warrant further investigation. In the isothermal reaction fronts problem, the characteristics of iso-surface propagation in a low Damköhler number regime are investigated. In premixed flames, the effects of non-stationarity on the turbulent burning velocity are addressed. The difference from the existing methods for determining turbulent burning velocity, and the implications of the present results for flames with multi-dimensional complex geometry are discussed. It is also shown that the surface mass flow density is related to the turbulent scalar flux in statistically stationary one-dimensional premixed flames. Variations of the local propagation characteristics due to departure from an unstretched laminar flame structure are shown to decrease the tendency to counter-gradient transport in turbulent premixed flames.

3

Martin, S. M., J. C. Kramlich, G. Kosa´ly, and J. J. Riley. "The Premixed Conditional Moment Closure Method Applied to Idealized Lean Premixed Gas Turbine Combustors." Journal of Engineering for Gas Turbines and Power 125, no. 4 (October 1, 2003): 895–900. http://dx.doi.org/10.1115/1.1587740.

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This paper presents the premixed conditional moment closure (CMC) method as a new tool for modeling turbulent premixed combustion with detailed chemistry. By using conditional averages the CMC method can more accurately model the affects of the turbulent fluctuations of the temperature on the reaction rates. This provides an improved means of solving a major problem with traditional turbulent reacting flow models, namely how to close the reaction rate source term. Combined with a commercial CFD code this model provides insight into the emission formation pathways with reasonable runtimes. Results using the full GRI2.11 methane kinetic mechanism are compared to experimental data for a backward-facing step burning premixed methane. This model holds promise as a design tool for lean premixed gas turbine combustors.

4

Watanabe, Tomoaki, Yasuhiko Sakai, Kouji Nagata, and Osamu Terashima. "Turbulent Schmidt number and eddy diffusivity change with a chemical reaction." Journal of Fluid Mechanics 754 (July 30, 2014): 98–121. http://dx.doi.org/10.1017/jfm.2014.387.

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AbstractWe provide empirical evidence that the eddy diffusivity$\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}D_{{t}\alpha }$and the turbulent Schmidt number${\mathit{Sc}}_{{t}\alpha }$of species$\alpha $($\alpha =\mathrm{A}, \mathrm{B}$or$\mathrm{R}$) change with a second-order chemical reaction ($\mathrm{A} + \mathrm{B} \rightarrow \mathrm{R}$). In this study, concentrations of the reactive species and axial velocity are simultaneously measured in a planar liquid jet. Reactant A is premixed into the jet flow and reactant B is premixed into the ambient flow. An optical fibre probe based on light absorption spectrometry is combined with I-type hot-film anemometry to simultaneously measure concentration and velocity in the reactive flow. The eddy diffusivities and the turbulent Schmidt numbers are estimated from the simultaneous measurement results. The results show that the chemical reaction increases${\mathit{Sc}}_{t\mathrm{A}}$;${\mathit{Sc}}_{t\mathrm{B}}$is negative in the region where the mean concentration of reactant B decreases in the downstream direction, and is positive in the non-reactive flow in the entire region on the jet centreline. It is also shown that${\mathit{Sc}}_{t\mathrm{R}}$is positive in the upstream region whereas it is negative in the downstream region. The production terms of axial turbulent mass fluxes of reactant B and product R can produce axial turbulent mass fluxes opposite to the axial gradients of the mean concentrations. The changes in the production terms due to the chemical reaction result in the negative turbulent Schmidt number of these species. These results imply that the gradient diffusion model using a global constant turbulent Schmidt number poorly predicts turbulent mass fluxes in reactive flows.

5

James, S., M. S. Anand, M. K. Razdan, and S. B. Pope. "In Situ Detailed Chemistry Calculations in Combustor Flow Analyses." Journal of Engineering for Gas Turbines and Power 123, no. 4 (March 1, 1999): 747–56. http://dx.doi.org/10.1115/1.1384878.

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In the numerical simulation of turbulent reacting flows, the high computational cost of integrating the reaction equations precludes the inclusion of detailed chemistry schemes, therefore reduced reaction mechanisms have been the more popular route for describing combustion chemistry, albeit at the loss of generality. The in situ adaptive tabulation scheme (ISAT) has significantly alleviated this problem by facilitating the efficient integration of the reaction equations via a unique combination of direct integration and dynamic creation of a look-up table, thus allowing for the implementation of detailed chemistry schemes in turbulent reacting flow calculations. In the present paper, the probability density function (PDF) method for turbulent combustion modeling is combined with the ISAT in a combustor design system, and calculations of a piloted jet diffusion flame and a low-emissions premixed gas turbine combustor are performed. It is demonstrated that the results are in good agreement with experimental data and computations of practical turbulent reacting flows with detailed chemistry schemes are affordable.

6

Albayrak, Alp, Deniz A. Bezgin, and Wolfgang Polifke. "Response of a swirl flame to inertial waves." International Journal of Spray and Combustion Dynamics 10, no. 4 (December 20, 2017): 277–86. http://dx.doi.org/10.1177/1756827717747201.

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Acoustic waves passing through a swirler generate inertial waves in rotating flow. In the present study, the response of a premixed flame to an inertial wave is scrutinized, with emphasis on the fundamental fluid-dynamic and flame-kinematic interaction mechanism. The analysis relies on linearized reactive flow equations, with a two-part solution strategy implemented in a finite element framework: Firstly, the steady state, low-Mach number, Navier–Stokes equations with Arrhenius type one-step reaction mechanism are solved by Newton’s method. The flame impulse response is then computed by transient solution of the analytically linearized reactive flow equations in the time domain, with mean flow quantities provided by the steady-state solution. The corresponding flame transfer function is retrieved by fitting a finite impulse response model. This approach is validated against experiments for a perfectly premixed, lean, methane-air Bunsen flame, and then applied to a laminar swirling flame. This academic case serves to investigate in a generic manner the impact of an inertial wave on the flame response. The structure of the inertial wave is characterized by modal decomposition. It is shown that axial and radial velocity fluctuations related to the eigenmodes of the inertial wave dominate the flame front modulations. The dispersive nature of the eigenmodes plays an important role in the flame response.

7

Yang, Wenkai, Ashraf N. Al Khateeb, and Dimitrios C. Kyritsis. "The Effect of Hydrogen Peroxide on NH3/O2 Counterflow Diffusion Flames." Energies 15, no. 6 (March 17, 2022): 2216. http://dx.doi.org/10.3390/en15062216.

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The impact of adding H2O2 in the fuel stream on the structure of non-premixed opposed-flow NH3/O2 flames was investigated numerically using a verified computational tool and validated mechanism. The results illustrate the dual role of the added H2O2 within the fuel jet. A small amount of H2O2 within the NH3 stream acted as a fuel additive that enhanced the reaction rate via reducing the kinetic time scale. However, a novel flame structure appeared when the H2O2 mole fraction within the fuel stream increased to χH2O2 > 16%. Unlike the pure NH3/O2 flame, a premixed reaction zone was discerned on the fuel side, in which H2O2 reacts with NH3 and played the role of an oxidizer. Then, the remaining NH3 that survived premixed combustion continues reacting with O2 and forms a non-premixed flame. As a result of this structure, it was shown that the well-established conclusion of “near-equilibrium” non-premixed flame analysis in which the strain on the flame is determined by the momentum fluxes of the counter-flowing streams does not hold for the flames that were studied in this paper. It was also shown that when H2O2 acted as an oxidizer, it produced substantial amounts of HO2, which allowed for low-temperature formation of NO2 through the reaction of NO with HO2.

8

Sauer, Vinicius M., Fernando F. Fachini, and Derek Dunn-Rankin. "Non-premixed swirl-type tubular flames burning liquid fuels." Journal of Fluid Mechanics 846 (May 4, 2018): 210–39. http://dx.doi.org/10.1017/jfm.2018.248.

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Tubular flames represent a canonical combustion configuration that can simplify reacting flow analysis and also be employed in practical power generation systems. In this paper, a theoretical model for non-premixed tubular flames, with delivery of liquid fuel through porous walls into a swirling flow field, is presented. Perturbation theory is used to analyse this new tubular flame configuration, which is the non-premixed equivalent to a premixed swirl-type tubular burner – following the original classification of premixed tubular systems into swirl and counterflow types. The incompressible viscous flow field is modelled with an axisymmetric similarity solution. Axial decay of the initial swirl velocity and surface mass transfer from the porous walls are considered through the superposition of laminar swirling flow on a Berman flow with uniform mass injection in a straight pipe. The flame structure is obtained assuming infinitely fast conversion of reactants into products and unity Lewis numbers, allowing the application of the Shvab–Zel’dovich coupling function approach.

9

Zhang, Yun Peng, Xiang Yang Wei, Xing Huang, and Bei Jing Zhong. "PAHs Formation Routes in the n-Heptane Laminar Flow Premixed Flame." Applied Mechanics and Materials 361-363 (August 2013): 1062–66. http://dx.doi.org/10.4028/www.scientific.net/amm.361-363.1062.

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A detailed reaction mechanism is adopted to simulate n-heptane laminar premixed flame in this paper. The reaction mechanism comprises 108 components and 572 elementary reactions. The main reactants (O2,n-C7H16), reaction products (CO2,CO,H2,H2O), intermediate products (CH4, C2H4, C2H2, C3Hx) and the concentration distribution of PAHs in the flame are analyzed in the numerical method. The numerical results are in good agreement with the experimental results, which states that the mechanism can predict PAHs in the n-heptane flame. In this paper, the sensitivity and reaction flow analysis method is used to analyze the numerical results and the PAHs formation routes in n-heptane laminar flow premixed flame are obtained.

10

Lin, Ying, Xuesong Li, Martyn V. Twigg, and William F. Northrop. "A non-premixed reactive volatilization reactor for catalytic partial oxidation of low volatility fuels at a short contact time." Reaction Chemistry & Engineering 6, no. 4 (2021): 662–71. http://dx.doi.org/10.1039/d0re00460j.

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This work presents a novel non-premixed opposed-flow reactive volatilization reactor that simultaneously vaporizes and partially oxidizes low volatility liquid hydrocarbons at a short contact time (<12 ms).

Більше джерел

Дисертації з теми "Reactive premixted flow":

1

Matino, Alessandra. "Characterisation of the Early Ignition Phase Generated by a Sunken Fire Igniter." Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2024. http://www.theses.fr/2024ESMA0008.

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Les restrictions environnementales abordent la réduction de l’utilisation des sources d’énergie primaires, motivant la recherche pour progresser vers des technologies améliorées. Parallèlement à ces efforts, la fiabilité et les performances doivent être assurées, en particulier dans des conditions délicates de pression et de température, c’est-à-dire en haute altitude. Dans les moteurs à turbine à gaz, ces deux éléments sont cruciaux pour offrir des produits qui répondent aux besoins et aux attentes fixés par le scénario actuel. L’allumage est un processus multiphysique constitué de plusieurs phases et événements qui concourent en couvrant une gamme diversifiée d’échelles de temps caractéristiques. La résolution numérique de la phase d’allumage précoce, pour laquelle des informations fines et détaillées font défaut, est étudiée dans cette étude. L’efficacité de l’allumeur est estimée par calorimétrie dans de l’air sec, ce qui montre que les variations de pression initiale ont une influence sur l’efficacité. La même étude a révélé que la température (20 ° C; - 20 ° C) par ailleurs a un effet négligeable. Les propriétés physiques du noyau en termes de volume, surface, surface de projection, rayon de l’arc électrique établi dans la cavité, sont estimées en adoptant différents diagnostics optiques, notamment de l’imagerie ultra rapide, strioscopie et ombroscopie à 1 MHz. Des calculs sont effectués pour obtenir une évolution temporelle pendant le temps de dépôt d’énergie (130 μs). Un effet de la pression initiale est observé sur les propriétés du noyau de telle sorte que avec la réduction de la pression initiale le volume du noyau augmente. De plus, des visualisations directes filtrées de la cavité de l’allumeur montrent qu’un effet de pression est discerné à partir de 20 μs. La taille du noyau est également mesurée pour des prémélanges de méthane pour différentes richesses. Cela vise à déterminer l’influence de la variation de la composition par rapport à un cas de référence dans du N2 pur qui est comparé aux mesures dans des prémélanges gazeux (à la fois de nature inerte CH4 / N2 et réactive CH4 / O2 / N2). Une comparaison entre les cas inertes et réactifs expose des réactions de combustion actives déjà pendant le dépôt d’énergie. Pour étudier l’exposition aux éléments d’un environnement réel, l’impact d’un écoulement transverse dans des conditions ambiantes est étudié dans une soufflerie. Cela a été adapté pour simuler l’effet combiné de l’écoulement transverse et de l’air de refroidissement auquel l’allumeur est exposé en étant monté dans une douille. L’effet de la douille sur la projection du noyau est étudié, révélant un impact sur la projection et la déformation du noyau en fonction de la vitesse imposée. La génération du noyau est examinée dans un écoulement réactif prémélangé à 0,45 et 1 bar. Le champ de vitesse a été étudié au préalable par PIV pour connaître la vitesse à proximité de l’allumeur et dans le domaine spatial où le noyau est projeté. Trois conditions de vitesse sont retenues pour effectuer la décharge. Il est observé que la pression initiale influence la déformation subie par le noyau en fonction de la vitesse initiale. En effet, à 1 bar, le noyau est préservé plus longtemps. Un effet secondaire de richesse est trouvé. Une étude préliminaire est réalisée pour explorer l’interaction entre le noyau et un spray de gouttes à 0,45 bar et 1 bar. Le fuel utilisé est du décane. L’ombroscopie à fort grossissement est le diagnostique utilisée pour effectuer des statistiques sur une fenêtre spatiale de 2 x 2 cm où des gouttelettes sont observées se déposer sur les électrodes. Des variations de leurs propriétés sont détectées en fonction de la synchronisation avec la décharge. Des visualisations par strioscopie sont ensuite réalisées pour observer qualitativement les phénomènes apparaissant dans une fenêtre temporelle de 1 ms. Le modèle existant de Taylor-Sedov est testé pour déterminer les capacités prédictives
Environmental restrictions tackle the reduction of the use of primary sources of energy motivating research to advance towards upgraded technologies. Alongside with these efforts, reliability and performance need to be ensured, especially for detrimental conditions of pressure and temperature, i.e. high altitude. In gas turbine engines, both these elements are crucial to offer products that fit to both the needs and expectations set by the present scenario. Ignition is a multiphase process constituted by several phases and events that span a diversified range of characteristic time scales. The numerical resolution of the early ignition phase, for which fine and detailed information is lacking, is investigated in this study. The efficiency of the igniter is estimated through calorimetry in pure air, which shows that variations of initial pressure have an influence on efficiency. The same investigation revealed that temperature (20° C; - 20°C) has a negligible effect. Physical properties of the kernel in terms of volume, surface, projection surface, radius of the arc channel in the cavity, are estimated adopting different optical diagnostics, including schlieren and shadowgraphy imaging at 1 MHz. Calculations are done to obtain a temporal evolution during energy depositing time (130 μs). An effect of initial pressure is observed on kernel properties such that reducing the initial pressure, kernel volume increases. Furthermore, filtered direct visualizations of the igniter cavity show that an effect of pressure is discerned from 20 μs. Kernel size is also measured for methane premixed mixtures of different equivalence ratios. This is intended to determine the influence of composition variation with respect to a reference case in pure N2 which is compared to measurements in gaseous premixed mixtures (both of inert CH4 / N2 and reactive CH4 / O2 / N2 nature). A comparison between inert and reactive cases exposes active combustion reactions already during energy deposition. To investigate the exposure to real life environment elements, the impact of a transverse flow at ambient conditions is studied in a wind tunnel. This was adapted to simulate the combined effect of a transverse flow and cooling air spilled from the liner that the igniter is exposed to by being mounted in a sleeve. The effect of the sleeve on kernel projection is investigated, which reveales an impact on projection and kernel deformation depending on the imposed velocity. The generation of the kernel is examined in a reactive premixed swirled mixture at 0.45 and 1 bar. The velocity field have been studied beforehand by PIV to know the velocity in the vicinity of the igniter and in the spatial domain where the kernel is projected. Three velocity conditions are retained to perform the discharge. Initial pressure is observed to influence the deformation the kernel undergoes depending on initial velocity. At 1 bar, the kernel appears to be preserved for longer. A secondary effect of equivalence ratio is found. The existing model of Taylor-Sedov is tested to predict kernel properties and compare them to experimental measurements. A preliminary study is performed to explore the interaction between the kernel and a spray at 0.45 bar and 1 bar. High magnification shadowgraphy is used to run statistics on a spatial window of 2 x 2 cm where droplets are observed impinging on the electrodes. Properties variations are detected depending on the synchronization with the discharge. Schlieren visualizations are further performed to observe phenomena to qualitatively explore the dynamics appearing in a time window of 1 ms

2

Smith, Thomas M. "Unsteady simulations of turbulent premixed reacting flows." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13097.

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3

Stevens, Eric John. "Velocity and scalar measurements in premixed turbulent reacting flows." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624921.

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4

Ahrens, Denise [Verfasser]. "NOx-Formation in Reacting Premixed Jets in Hot Cross Flow / Denise Ahrens." München : Verlag Dr. Hut, 2015. http://d-nb.info/1077404093/34.

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5

Yellugari, Kranthi. "Effects of Swirl Number and Central Rod on Flow in Lean Premixed Swirl Combustor." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563872979440851.

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6

Wu, Men-Zan B. "Velocity and temperature measurements in a non-premixed reacting flow behind a backward facing step." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/12045.

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7

Ito, Yasumasa. "Promotion of fluid mixing and chemical reaction in non-premixed liquid flows." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136342.

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8

Paul, Sreebash Chandra. "Large eddy simulation of a fuel-rich turbulent non-premixed reacting flow with radiative heat transfer." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/203/.

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The aims of this thesis are to apply the Large Eddy Simulation (LES) and beta Probability Density Function (β- PDF) for the simulation of turbulent non-premixed reacting flow, in particularly for the predictions of soot and NO production, and to investigate the radiative heat transfer during combustion process applying Discrete Ordinates Method (DOM). LES seeks the solution by separating the flow field into large-scale eddies, which carry the majority of the energy and are resolved directly, and small-scale eddies, which have been modelled via Smagorinsky model with constant Cs (Smagorinsky model constant) as well as its dynamic calibration. This separation has been made by applying a filtering approach to the governing equations describing the turbulent reacting flow. Firstly, LES technique is applied to investigate the turbulent flow, temperature and species concentrations during the combustion process within an axi-symmetric model cylindrical combustion chamber. Gaseous propane (C3H8) and preheated air of 773K are injected into this cylindrical combustion chamber. The non-premixed combustion process is modelled through the conserved scalar approach with the laminar flamelet model. A detailed chemical mechanism is taken into account to generate the flamelet. The turbulent combustion inside the chamber takes place under a fuel-rich condition for which the overall equivalence ratio of 1.6 is used, the same condition was used by Nishida and Mukohara [1] in their experiment. Secondly, the soot formation in the same flame is investigated by using the LES technique. In this thesis, the soot formation is included through the balance equations for soot mass fraction and soot particle number density with finite rate kinetic source terms to account for soot inception/nucleation, surface growth, agglomeration and oxidation. Thirdly, the NO formation in the flame is studied by applying the LES. The formation of NO is modelled via the extended Zeldovich (thermal) reaction mechanism. A transport equation for NO mass fraction is coupled with the flow and composition fields. Finaly, the radiative heat transfer in the flame is investigated. Both the luminous and non-luminous radiations are modelled through the Radiative Transfer Equation (RTE). The RTE is solved using the Discrete Ordinates Method (DOM/Sn) combining with the LES of the flow, temperature, combustion species and soot formation. The computed results are compared with the available experimental results and the level of agreement between measurements and computations is quite good.

9

Tokekar, Devkinandan Madhukar. "Modeling and simulation of reacting flows in lean-premixed swirl-stabilized gas turbine combustor." Cincinnati, Ohio : University of Cincinnati, 2005. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1141412599.

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Thesis (M.S.)--University of Cincinnati, 2005.
Title from electronic thesis title page (viewed Apr. 18, 2006). Includes abstract. Keywords: Large Eddy Simulation; LES; Lean Pre-mixed; LPM; Gas Turbine Combustor; Combustion; Reacting Flows. Includes bibliographical references.

10

TOKEKAR, DEVKINANDAN MADHUKAR. "MODELING AND SIMULATION OF REACTING FLOWS IN LEAN-PREMIXED SWIRL-STABLIZED GAS TURBINE COMBUSTOR." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141412599.

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Книги з теми "Reactive premixted flow":

1

C, So Ronald M., and United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., eds. On the modelling of non-reactive and reactive turbulent combustor flows. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1987.

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2

Nikjooy, Mohammad. On the modelling of non-reactive and reactive turbulent combustor flows. Cleveland, Ohio: Lewis Research Center, 1987.

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3

Wu, Men-Zan Bill. Velocity and temperature measurements in a non-premixed reacting flow behind a backward facing step. Atlanta, Ga: Georgia Institute of Technology, 1992.

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4

On the modelling of non-reactive and reactive turbulent combustor flows. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1987.

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Частини книг з теми "Reactive premixted flow":

1

Iavarone, S., H. Yang, Z. Li, Z. X. Chen, and N. Swaminathan. "On the Use of Machine Learning for Subgrid Scale Filtered Density Function Modelling in Large Eddy Simulations of Combustion Systems." In Lecture Notes in Energy, 209–43. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-16248-0_8.

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AbstractThe application of machine learning algorithms to model subgrid-scale filtered density functions (FDFs), required to estimate filtered reaction rates for Large Eddy Simulation (LES) of chemically reacting flows, is discussed in this chapter. Three test cases, i.e., a low-swirl premixed methane-air flame, a MILD combustion of methane-air mixtures, and a kerosene spray turbulent flame, are presented. The scalar statistics in these test cases may not be easily represented using the commonly used presumed shapes for modeling FDFs of mixture fraction and progress variable. Hence, the use of ML methods is explored. Particularly, deep neural network (DNN) to infer joint FDFs of mixture fraction and progress variable is reviewed here. The Direct Numerical Simulation (DNS) datasets employed to train the DNNs in each test case are described. The DNN performances are shown and compared to typical presumed probability density function (PDF) models. Finally, this chapter examines the advantages and caveats of the DNN-based approach.

2

Hamel, F., and R. Monneau. "Conical-Shaped Travelling Fronts Allied to the Mathematical Analysis of the Shape of Premixed Bunsen Flames." In Nonlinear PDE’s in Condensed Matter and Reactive Flows, 169–87. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0307-0_8.

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"Flows with Premixed Reactants." In An Introduction to Turbulent Reacting Flows, 87–132. PUBLISHED BY IMPERIAL COLLEGE PRESS AND DISTRIBUTED BY WORLD SCIENTIFIC PUBLISHING CO., 2007. http://dx.doi.org/10.1142/9781848161368_0005.

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4

"Flows with Non-premixed Reactants." In An Introduction to Turbulent Reacting Flows, 63–86. PUBLISHED BY IMPERIAL COLLEGE PRESS AND DISTRIBUTED BY WORLD SCIENTIFIC PUBLISHING CO., 2007. http://dx.doi.org/10.1142/9781848161368_0004.

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"Extinction of Premixed Curved Flames Stabilized in a Stagnation Flow." In Dynamics of Deflagrations and Reactive Systems: Flames, 161–75. Washington DC: American Institute of Aeronautics and Astronautics, 1991. http://dx.doi.org/10.2514/5.9781600866043.0161.0175.

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"Laminar Premixed Flames: Simulation of Combustion in the Flame Front." In Chemical Kinetics in Combustion and Reactive Flows, 207–27. Cambridge University Press, 2019. http://dx.doi.org/10.1017/9781108581714.004.

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7

"Flame Curvature and Flame Speed of a Turbulent Premixed Flame in a Stagnation Point Flow." In Dynamics of Heterogeneous Combustion and Reacting Systems, 25–36. Washington DC: American Institute of Aeronautics and Astronautics, 1993. http://dx.doi.org/10.2514/5.9781600866258.0025.0036.

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Koutmos, P., C. Mavridis, and D. Papailiou. "A study of turbulent isothermal and non-premixed reacting wake flows past a two-dimensional square cylinder." In Engineering Turbulence Modelling and Experiments, 797–806. Elsevier, 1996. http://dx.doi.org/10.1016/b978-0-444-82463-9.50082-4.

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Тези доповідей конференцій з теми "Reactive premixted flow":

1

Wahid, Mazlan A., M. Z. Ahmad Faiz, M. A. Wahid, S. Samion, N. A. C. Sidik, and J. M. Sheriff. "Swirling Lean-Premixed Reacting Flow." In THE 10TH ASIAN INTERNATIONAL CONFERENCE ON FLUID MACHINERY. AIP, 2010. http://dx.doi.org/10.1063/1.3464844.

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2

Kru¨ger, Oliver, Katharina Go¨ckeler, Sebastian Go¨ke, Christian Oliver Paschereit, Christophe Duwig, and Laszlo Fuchs. "Numerical Investigations of a Swirl-Stabilized Premixed Flame at Ultra-Wet Conditions." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45866.

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The present study focuses on the numerical investigation of a generic swirl-stabilized burner operated with methane at ultra-wet conditions. The burner is fed with a preheated homogeneous mixture formed by steam and air. As a set of operating conditions atmospheric pressure, inlet temperature of 673K, equivalence ratio of 0.85 and a steam content of 30% is applied. Large eddy simulations have been performed to investigate the flow features. In a first step the non-reacting flow field was investigated with water as working medium. Comparison with Particle Image Velocimetry (PIV) and Laser-Doppler Velocimetry (LDV) measurements conducted in a water tunnel facility showed that an excellent agreement within the experimental uncertainty is obtained for the flow field. A dominant frequency in the turbulent energy spectrum was identified, which corresponds to the motion associated with a precessing vortex core (PVC). In order to investigate the reactive flow in a second step, a customized solver for handling low Mach number reacting flows based on an implicit LES approach was developed. As reaction mechanism a reduced 4 steps / 7 species global scheme was used. To compare the simulations qualitatively with a wet flame, OH chemiluminescence pictures serve as a reference. The simulations showed a more compact flame compared to the OH pictures. Nevertheless, the prolongation and position of the flame were found to be reasonable. The reduced mechanism captures the main effects, such as the reduction of the peak and mean temperatures. Furthermore, the presence of a PVC in the reacting flow could be determined and was not suppressed by heat-release.

3

Hamlington, Peter, Alexei Poludnenko, and Elaine Oran. "Intermittency and Premixed Turbulent Reacting Flows." In 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2011. http://dx.doi.org/10.2514/6.2011-113.

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4

Martin, Scott M., John C. Kramlich, George Kosa´ly, and James J. Riley. "The Premixed Conditional Moment Closure Method Applied to Idealized Lean Premixed Gas Turbine Combustors." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30094.

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This paper presents the premixed Conditional Moment Closure (CMC) method as a new tool for modeling turbulent premixed combustion with detailed chemistry. By using conditional averages the CMC method can more accurately model the affects of the turbulent fluctuations of the temperature on the reaction rates. This provides an improved means of solving a major problem with traditional turbulent reacting flow models, namely how to close the reaction rate source term. Combined with a commercial CFD code this model provides insight into the emission formation pathways with reasonable runtimes. Results using the full GRI2.11 methane kinetic mechanism are compared to experimental data for a backward facing step burning premixed methane. This model holds promise as a design tool for lean premixed gas turbine combustors.

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Santosh Kumar, T. V., P. R. Alemela, and J. B. W. Kok. "Dynamics of Flame Stabilized by Triangular Bluff Body in Partially Premixed Methane-Air Combustion." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46241.

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In the design and operational tuning of gas turbine combustors it is important to be able to predict the interaction of the flame stabilization recirculation area with the burner aerodynamics. In the present paper transient computational fluid dynamics analysis is used to study these effects. Vortex interactions with the flame play a key role in many practical combustion systems. The interactions drive a large class of combustion instabilities and are responsible for changing the reaction rates, shape of the flame and the global heat release rate. The evolution of vortex shedding in reactive flows and its effects on the dynamics of the flame are important to be predicted. The present study describes dynamics of bluff body stabilized flames in a partially premixed combustion system. The bluff body is an equilateral wedge that induces the flame recirculation zone. The wedge is positioned at one-third length of the duct, which, is acoustically closed at the bottom end and open at the top. Transient computational modeling of partially premixed combustion is carried out using the commercial ANSYS CFX code and the results show that the vortex shedding has a destabilizing effect on the combustion process. Scale Adaptive Simulation turbulence model is used to compare between non-reacting cases and combustion flows to show the effects of aerodynamics-combustion coupling. The transient data reveals that frequency peaks of pressure and temperature spectra and is consistent with the longitudinal natural frequencies and Kelvin-Helmholtz instability frequency for reactive flow simulations. The same phenomenon is observed at different operating conditions of varying power. It has also been shown that the pressure and heat release are in phase, satisfying the Rayleigh criterion and therefore indicating the presence of aerodynamic-combustion instability. The data are compared to the scarce data on experiments and simulations available in literature.

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Mulas, Marco, and Marco Talice. "Fully Compressible Simulation of Low-Speed Premixed Reactive Flows." In 33rd AIAA Fluid Dynamics Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2003. http://dx.doi.org/10.2514/6.2003-4253.

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7

De, Ashoke, Shengrong Zhu, and Sumanta Acharya. "An Experimental and Computational Study of a Swirl-Stabilized Premixed Flame." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-60230.

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An unconfined strongly swirled flow is investigated for different Reynolds numbers using particle image velocimetry (PIV) and Large Eddy Simulation (LES) with a Thickened Flame (TF) model. Both reacting and non-reacting flow results are presented. In the LES-TF approach, the flame front is resolved on the computational grid through artificial thickening and the individual species transport equations are directly solved with the reaction rates specified using Arrhenius chemistry. Good agreement is found when comparing predictions with the experimental data for the non-reacting cases studied. For the reacting flows, the mean axial velocity profiles are in good agreement with measurements at lower Re; at high Re, the computations show a more compact and attached flame whereas experimental observations show a slightly lifted flame. Tangential velocity predictions consistently show the peak at the flame front location while measurements show greater radial spreading of the tangential momentum. The predicted RMS fluctuations exhibit a double-peak profile with one peak in the burnt and the other in the unburnt region. The measured and predicted heat release distributions are in qualitative agreement with each other and exhibit the highest values along the inner edge of the shear layer. The precessing vortex core (PVC) is clearly observed in both the non-reacting and reacting cases. However, it appears more axially-elongated for the reacting cases.

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James, S., M. S. Anand, M. K. Razdan, and S. B. Pope. "In Situ Detailed Chemistry Calculations in Combustor Flow Analyses." In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-271.

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In the numerical simulation of turbulent reacting flows, the high computational cost of integrating the reaction equations precludes the inclusion of detailed chemistry schemes, therefore reduced reaction mechanisms have been the more popular route for describing combustion chemistry, albeit at the loss of generality. The in situ adaptive tabulation scheme (ISAT) has significantly alleviated this problem by facilitating the efficient integration of the reaction equations via a unique combination of direct integration and dynamic creation of a look-up table, thus allowing for the implementation of detailed chemistry schemes in turbulent reacting flow calculations. In the present paper, the probability density function (PDF) method for turbulent combustion modeling is combined with the ISAT in a combustor design system, and calculations of a piloted jet diffusion flame and a low-emissions premixed gas turbine combustor are performed. It is demonstrated that the results are in good agreement with experimental data and computations of practical turbulent reacting flows with detailed chemistry schemes are affordable.

9

Uchiyama, Tomomi, and Naohiro Otsuki. "Numerical Simulation for Free Turbulent Reacting Flow by Particle Method." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45289.

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This paper presents a particle method for free turbulent reacting flows. The vorticity and concentration fields are discretized into the vortex and concentration elements, respectively, and the behavior of the elements is calculated with the Lagrangian method. The chemical reaction is estimated through the Lagrangian calculation for the strength of concentration element. The particle method is applied to simulate a plane mixing layer with a single-step and irreversible chemical reaction of non-premixed reactants so as to discuss the applicability.

10

Chakravorty, Saugata, and Joseph Mathew. "Explicit Filtering LES for Turbulent Non-Premixed Combustion." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37361.

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Two models for large eddy simulation of turbulent reacting flow in homogeneous turbulence were studied. The sub-grid stress arising out of non-linearities of the Navier-Stokes equations were modeled using an explicit filtering approach. A filtered mass density function (FMDF) approach was used for closure of the sub-grid scalar fluctuations. A posteriori calculations, when compared with the results from the direct numerical simulation, indicate that the explicit filtering is adequate in representing the effect of sub-grid stress on the filtered velocity field in the absence of reaction. Discrepancies arise when reactions occur, but the FMDF approach suffices to account for sub-grid scale fluctuations of the reacting scalars, accurately.

Звіти організацій з теми "Reactive premixted flow":

1

Chapman and Toema. PR-266-07209-R01 Phase 2 - Assessment of the Robustness and Transportability of the Gas Turbine Model. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 2010. http://dx.doi.org/10.55274/r0010719.

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This report presents the modeling study of a gas turbine combustor based on first engineering principles to fully characterize the nitrogen oxides (NOx) and carbon monoxide emissions (CO). The model is mainly focused on the emissions from the widely used lean-premixed, dry low-NOx combustor. The combustor is divided into several zones where each zone can be considered as a plug-flow reactor. Each of these zones is assumed to have a uniform pressure, temperature and perfect mixing between combustion species. The temperature of each zone is calculated using mass and energy balances along with heat transfer through the combustor liner. The emissions are calculated using well-know pollutant reaction schemes such as the Zeldovich mechanism in addition to other well-established semi-empirical correlations.