Статті в журналах: "Eddy dissipation concept (EDC)"

1

Bösenhofer, Markus, Eva-Maria Wartha, Christian Jordan, and Michael Harasek. "The Eddy Dissipation Concept—Analysis of Different Fine Structure Treatments for Classical Combustion." Energies 11, no. 7 (July 20, 2018): 1902. http://dx.doi.org/10.3390/en11071902.

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The Eddy Dissipation Concept (EDC) is common in modeling turbulent combustion. Several model improvements have been proposed in literature; recent modifications aim to extend its validity to Moderate or Intense Low oxygen Dilution (MILD) conditions. In general, the EDC divides a fluid into a reacting and a non-reacting part. The reacting part is modeled as perfectly stirred reactor (PSR) or plug flow reactor (PFR). EDC theory suggests PSR treatment, while PFR treatment provides numerical advantages. Literature lacks a thorough evaluation of the consequences of employing the PFR fine structure treatment. Therefore, these consequences were evaluated by employing tests to isolate the effects of the EDC variations and fine structure treatment and by conducting a Sandia Flame D modeling study. Species concentration as well as EDC species consumption/production rates were evaluated. The isolated tests revealed an influence of the EDC improvements on the EDC rates, which is prominent at low shares of the reacting fluid. In contrast, PSR and PFR differences increase at large fine fraction shares. The modeling study revealed significant differences in the EDC rates of intermediate species. Summarizing, the PFR fine structure treatment might be chosen for schematic investigations, but for detailed investigations a careful evaluation is necessary.

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2

Shen, Bin Xian, and Wei Qiang Liu. "Numerical Simulation of Turbulence-Chemical Interaction Models on Combustible Particle MILD Combustion." Advanced Materials Research 1070-1072 (December 2014): 1752–57. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.1752.

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Typical combustible particle coal has been analyzed by using turbulence-chemistry interaction models to realize which models are more accurate and reasonable on pulverized coal MILD combustion. Three turbulence-chemistry interaction models are examined: the Equilibrium Mixture Fraction/PDF (PDF), the Eddy Break Up (EBU), the Eddy Dissipation Concept (EDC). All of three models can give a suitable prediction of axial velocity on combustible particle coal MILD combustion because turbulence-chemistry interaction models have little influence on flow field and flow structure. The Eddy Dissipation Concept model (EDC), based on advanced turbulence-chemistry interaction with global and detailed kinetic mechanisms can produce satisfactory results on chemical and fluid dynamic behavior of combustible particle coal MILD combustion, especially on temperature and species concentrations.

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3

Martinez-Sanchis, Daniel, Andrej Sternin, Jaroslaw Shvab, Oskar Haidn, and Xiangyu Hu. "An Eddy Dissipation Concept Performance Study for Space Propulsion Applications." Aerospace 9, no. 9 (August 27, 2022): 476. http://dx.doi.org/10.3390/aerospace9090476.

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In this study, Direct Numerical Simulations (DNS) of a turbulent diffusion flame are conducted to investigate the performance of the Eddy Dissipation Concept in turbulent combustion for space propulsion applications. A 20-bar methane-oxygen diffusion flame is simulated to resemble the conditions encountered in modern rocket combustors. The numerical simulations were conducted using the software EBI-DNS within the OpenFOAM framework. An approach for analysis and validation of the combustion model with DNS is developed. The EDC model presents a good agreement with DNS observations in the most prevalent species. Nevertheless, the EDC struggles to predict the mean chemical production rate of intermediate species. It is found that local adaption of the model constants is essential for maximizing the prediction capabilities. The relationship of these parameters with the Reynolds number and the Damköhler number are mostly in good agreement with the trends proposed in recent research .

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4

He, Di, Yusong Yu, Hao Ma, Hongbo Liang, and Chaojun Wang. "Extensive Discussions of the Eddy Dissipation Concept Constants and Numerical Simulations of the Sandia Flame D." Applied Sciences 12, no. 18 (September 13, 2022): 9162. http://dx.doi.org/10.3390/app12189162.

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The indisputable wide use of the Eddy Dissipation Concept (EDC) implies that the resulting mean reaction rate is reasonably well modeled. To model turbulent combustions, an amount of EDC constants that differ from the original values was proposed. However, most of them were used without following the nature of the model or considering the effects of the modification. Starting with the energy cascade and the EDC models, the exact original primary and secondary constants are deduced in detail in this work. The mean reaction rate is then formulated from the primary constants or the secondary constants. Based on the physical meaning of fine structures, the limits of the EDC constants are presented and can be used to direct the EDC constant modifications. The effects of the secondary constant on the mean reaction rate are presented and the limiting turbulence Reynolds number used for the validity of EDC is discussed. To show the effects of the constants of the EDC model on the mean reaction rate, 20 combinations of the primary constants are used to simulate a laboratory-scale turbulent jet flame, i.e., Sandia Flame D. After a thorough and careful comparison with experiments, case 8, with a secondary constant of 6 and primary constants of 0.1357 and 0.11, can aptly reproduce this flame, except for in the over-predicted mean OH mass fraction.

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5

Ertesvåg, Ivar S. "Analysis of Some Recently Proposed Modifications to the Eddy Dissipation Concept (EDC)." Combustion Science and Technology 192, no. 6 (May 5, 2019): 1108–36. http://dx.doi.org/10.1080/00102202.2019.1611565.

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6

Kuang, Yucheng, Boshu He, Chaojun Wang, Wenxiao Tong, and Di He. "Numerical analyses of MILD and conventional combustions with the Eddy Dissipation Concept (EDC)." Energy 237 (December 2021): 121622. http://dx.doi.org/10.1016/j.energy.2021.121622.

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7

Fukumoto, Kazui, and Yoshifumi Ogami. "Simulation of CO-H2-Air Turbulent Nonpremixed Flame Using the Eddy Dissipation Concept Model with Lookup Table Approach." Journal of Combustion 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/496460.

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We present a new combustion simulation technique based on a lookup table approach. In the proposed technique, a flow solver extracts the reaction rates from the look-up table using the mixture fraction, progress variable, and reaction time. Look-up table building and combustion simulation are carried out simultaneously. The reaction rates of the chemical species are recorded in the look-up table according to the mixture fraction, progress variable, and time scale of the reaction. Once the reaction rates are recorded, a direct integration to solve the chemical equations becomes unnecessary; thus, the time for computing the reaction rates is shortened. The proposed technique is applied to an eddy dissipation concept (EDC) model and it is validated through a simulation of a CO-H2-air nonpremixed flame. The results obtained by using the proposed technique are compared with experimental and computational data obtained by using the EDC model with direct integration. Good agreement between our method and the EDC model and the experimental data was found. Moreover, the computation time for the proposed technique is approximately 99.2% lower than that of the EDC model with direct integration.

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8

Sedano, Camilo, Omar López, Alexander Ladino, and Felipe Muñoz. "Prediction of a methane circular pool fire with fireFoam." MATEC Web of Conferences 240 (2018): 05026. http://dx.doi.org/10.1051/matecconf/201824005026.

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In the present work, the fireFoam solver was used with Large Eddy Simulation (LES) and the Eddy Dissipation Concept (EDC) for modelling a medium-scale methane pool fire. A convergence analysis performed, showed that a 2 Million elements three-dimensional mesh, is good enough to attain good numerical results. By comparing the numerical results obtained, with the experimental ones, as well as numerical results from previous studies, it was proven that the fireFoam solver is able to obtain satisfactory results.

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9

Ali, Akram Ben, Mansour Karkoub, and Mouldi Chrigui. "Numerical Investigation of Turbulent Premixed Combustion of Methane / Air in Low Swirl Burner under Elevated Pressures and Temperatures." International Journal of Heat and Technology 39, no. 1 (February 28, 2021): 155–60. http://dx.doi.org/10.18280/ijht.390116.

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Turbulent combustion modeling of lean premixed methane/air gas mixture in a low swirl burner is carried out using Large Eddy Simulation (LES). The operating conditions of the experiment as well as simulation are carried out at elevated pressure and temperature. The first case-simulation is a premixed combustion model based on C-equation formulation, the second one is based on species transport – Eddy Dissipation Concept (EDC) model. Numerical results for axial velocity and turbulence intensity along the centerline showed a good agreement against the experimental data. Quantitative results of OH mass fraction contour showing the flame structure are in a plausible agreement compared to the experimental measurement.

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10

Sedano, Camilo Andrés, Omar Darío López, Alexander Ladino, and Felipe Muñoz. "Prediction of a Small-Scale Pool Fire with FireFoam." International Journal of Chemical Engineering 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/4934956.

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A computational model using Large Eddy Simulation (LES) for turbulence modelling was implemented, by means of the Eddy Dissipation Concept (EDC) combustion model using the fireFoam solver. A small methanol pool fire experiment was simulated in order to validate and compare the numerical results, hence trying to validate the effectiveness of the solver. A detailed convergence analysis is performed showing that a mesh of approximately two million elements is sufficient to achieve satisfactory numerical results (including chemical kinetics). A good agreement was achieved with some of the experimental and previous computational results, especially in the prediction of the flame height and the average temperature contours.

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11

Cemal Benim, Ali, and Björn Pfeiffelmann. "Validation of Combustion Models for Lifted Hydrogen Flame." E3S Web of Conferences 128 (2019): 01014. http://dx.doi.org/10.1051/e3sconf/201912801014.

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Within a Reynolds Averaged Numerical Simulation (RANS) approach for turbulence modelling, a computational investigation of a turbulent lifted H2/N2 flame is presented. Various turbulent combustion models are considered including the Eddy Dissipation Model (EDM), the Eddy Dissipation Concept (EDC), and the composition Probability Density Function transport model (PDF) in combination with different detailed and global reaction mechanisms. Turbulence is modelled using the Standard k-ɛ model, which has proven to offer a good accuracy, based on a preceding validation study for an isothermal H2/N2 jet. Results are compared with the published measurements for a lifted H2/N2 flame, and the relative performance ofthe turbulent combustion models are assessed. It is observed that the prediction quality can vary largely depending on the reaction mechanism and the turbulent combustion model. The best and quite satisfactory agreement with experiments is provided by two detailed reaction mechanisms applied with a PDF model.

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12

Sloan, D. G., and G. J. Sturgess. "Modeling of Local Extinction in Turbulent Flames." Journal of Engineering for Gas Turbines and Power 118, no. 2 (April 1, 1996): 292–307. http://dx.doi.org/10.1115/1.2816591.

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The Eddy Dissipation Concept (EDC), proposed by Magnussen (1985), advances the concept that the reactants are homogeneously mixed within the fine eddy structures of turbulence and that the fine structures may therefore be regarded as perfectly stirred reactors (PSRs). To understand more fully the extent to which such a subgrid scale stirred reactor concept could be applied within the context of a computational fluid dynamics (CFD) calculation to model local or global extinction phenomena: (1) Various kinetic mechanisms are investigated with respect to CPU penalty and predictive accuracy in comparisons with stirred reactor lean blowout (LBO) data and (2) a simplified time-scale comparison, extracted from the EDC model and applied locally in a fast-chemistry CFD computation, is evaluated with respect to its capabilities to predict attached and lifted flames. Comparisons of kinetic mechanisms with PSR lean blowout data indicate severe discrepancies in the predictions with the data and with each other. Possible explanations are delineated and discussed. Comparisons of the attached and lifted flame predictions with experimental data are presented for some benchscale burner cases. The model is only moderately successful in predicting lifted flames and fails completely in the attached flame case. Possible explanations and research avenues are reviewed and discussed.

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13

Kang, Zhizhong, Shixing Ding, Zhi-ang Shuai, and Baomin Sun. "Modeling of coal combustion in the CFB by the EDC model with the global reaction mechanism." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 4 (April 3, 2018): 963–81. http://dx.doi.org/10.1108/hff-11-2016-0467.

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Purpose This paper aims to shows the ability of the EDC model with a global reaction mechanism to describe reactions in the Eulerian simulation of a circulating fluidized bed (CFB). Design/methodology/approach The eddy dissipation concept (EDC) model is embedded in an Eulerian-Eulerian approach to simulate homogeneous reactions. Findings EDC_G is better than ED_FR in describing chemical reactions. The reaction of CH4 with O2 is faster than that of CO with O2, and NH3 is more liable to be converted than HCN. The combustion rate is higher than the Boudouard reaction rate of coal particles.N2O is mainly reduced by carbon, and NO is mainly converted by carbon into N2 and CO2. Originality/value The EDC model with a global reaction mechanism is embedded in a multi-fluid Eulerian approach to simulate the homogeneous reactions in the coal combustion in a CFB, including combustion of volatile gases, desulfurizing reactions and NOx reactions.

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14

Zhou, Lu, Shu Zhong Wang, and Hong He Ma. "CFD Simulation of a SCWO Reactor Containing a Hydrothermal Flame." Advanced Materials Research 516-517 (May 2012): 58–61. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.58.

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A supercritical water oxidation (SCWO) reactor containing a hydrothermal flame as heat source is simulated by computational fuild dynamics (CFD) simulation. Methanol solution and oxygen are fed separately into the reactor as fuel and oxidizer, and at the same time the cold waste water is also fed into the reactor. The combustion of methanol is simulated by the eddy dissipation concept (EDC) model with an Arrhenius law kinetic. This simulation is conducted to study the behavior of the hydrothermal flame at different inlet fuel temperatures and the relationship between the ignition temperature and methanol mass fraction.

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15

Zhang, Jin Yan, Hong Sheng Liu, and Zhen Jie Xu. "Numerical Study on the Premixed Combustion in Porous Media Burner." Advanced Materials Research 614-615 (December 2012): 73–76. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.73.

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The phenomenon of combustion of a gaseous mixture in a two-dimension alumina ( ) particle packed bed porous media burner is studied by means of a numerical simulation with FLUENT software using two-step reaction mechanism. The Eddy-dissipation-concept (EDC) model, the standard model and the Discrete- Ordinates (DO) radiation model are used in this paper. It is concluded that the methane/air gas mixture with lower equivalence ratio or with faster inlet velocity, can achieve the faster wave propagates. The methane/air gas mixture with lower equivalence ratio or with faster inlet velocity, can achieve the faster wave propagates.

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16

Jeffery, Christopher A., and Jon M. Reisner. "A Study of Cloud Mixing and Evolution Using PDF Methods. Part I: Cloud Front Propagation and Evaporation." Journal of the Atmospheric Sciences 63, no. 11 (November 1, 2006): 2848–64. http://dx.doi.org/10.1175/jas3760.1.

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Abstract The evolution of mean relative humidity (RH) is studied in an isobaric system of clear and cloudy air mixed by an incompressible velocity field. A constant droplet radius assumption is employed that implies a simple dependence of the mixing time scale, τeddy, and the reaction (evaporation) time scale, τreact, on the specifics of the droplet size spectrum. A dilemma is found in the RH e-folding time, τefold, predicted by two common microphysical schemes: models that resolve supersaturation and ignore subgrid correlations, which gives τefold ∼ τreact, and PDF schemes that assume instantaneous evaporation and predict τefold ∼ τeddy. The resolution of this dilemma, Magnussen and Hjertager’s eddy dissipation concept (EDC) model τefold ∼ max(τeddy, τreact), is revealed in the results of 1D eddy diffusivity simulations and a new probability density function (PDF) approach to cloud mixing and evolution in which evaporation is explicitly resolved and the shape of the PDF is not specified a priori. The EDC model is shown to exactly solve the nonturbulent problem of spurious production of cloud-edge supersaturations described by Stevens et al. and produce good results in the more general turbulent case.

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17

Benim, Ali Cemal, and Björn Pfeiffelmann. "Comparison of Combustion Models for Lifted Hydrogen Flames within RANS Framework." Energies 13, no. 1 (December 28, 2019): 152. http://dx.doi.org/10.3390/en13010152.

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Within the framework of a Reynolds averaged numerical simulation (RANS) methodology for modeling turbulence, a comparative numerical study of turbulent lifted H2/N2 flames is presented. Three different turbulent combustion models, namely, the eddy dissipation model (EDM), the eddy dissipation concept (EDC), and the composition probability density function (PDF) transport model, are considered in the analysis. A wide range of global and detailed combustion reaction mechanisms are investigated. As turbulence model, the Standard k-ε model is used, which delivered a comparatively good accuracy within an initial validation study, performed for a non-reacting H2/N2 jet. The predictions for the lifted H2/N2 flame are compared with the published measurements of other authors, and the relative performance of the turbulent combustion models and combustion reaction mechanisms are assessed. The flame lift-off height is taken as the measure of prediction quality. The results show that the latter depends remarkably on the reaction mechanism and the turbulent combustion model applied. It is observed that a substantially better prediction quality for the whole range of experimentally observed lift-off heights is provided by the PDF model, when applied in combination with a detailed reaction mechanism dedicated for hydrogen combustion.

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18

Ertesvåg, Ivar S. "Scrutinizing proposed extensions to the Eddy Dissipation Concept (EDC) at low turbulence Reynolds numbers and low Damköhler numbers." Fuel 309 (February 2022): 122032. http://dx.doi.org/10.1016/j.fuel.2021.122032.

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19

Shamooni, A., A. Cuoci, T. Faravelli, and A. Sadiki. "An a priori DNS analysis of scale similarity based combustion models for LES of non-premixed jet flames." Flow, Turbulence and Combustion 104, no. 2-3 (December 30, 2019): 605–24. http://dx.doi.org/10.1007/s10494-019-00099-9.

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AbstractIn this work, recently developed finite-rate dynamic scale similarity (SS) sub-grid scale (SGS) combustion models have been a priori assessed and compared with the Eddy Dissipation Concept (EDC) and “no model” approaches based on a Direct Numerical Simulation (DNS) database of a temporally evolving non-premixed jet flame. Two different filter widths, one placed in the inertial range and the other in the near dissipation range, have been used. The analyses were carried out in two time instants corresponding to instants of maximum local extinction and re-ignition. Conditional averaged filtered chemical source terms, conditioned on different parameters in the composition space, have been presented. Improvements are observed using the dynamic SS models compared to the two other approaches in the prediction of filtered chemical source terms of individual species while using larger filter widths. However, discrepancies still exists using the dynamic SS model on the turbulent/non-turbulent interfaces of the jet, mainly in the prediction of the oxidizer consumption rate.

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20

Abdul-Sater, Hassan, Gautham Krishnamoorthy, and Mario Ditaranto. "Predicting Radiative Heat Transfer in Oxy-Methane Flame Simulations: An Examination of Its Sensitivities to Chemistry and Radiative Property Models." Journal of Combustion 2015 (2015): 1–20. http://dx.doi.org/10.1155/2015/439520.

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Measurements from confined, laminar oxy-methane flames at different O2/CO2dilution ratios in the oxidizer are first reported with measurements from methane-air flames included for comparison. Simulations of these flames employing appropriate chemistry and radiative property modeling options were performed to garner insights into the experimental trends and assess prediction sensitivities to the choice of modeling options. The chemistry was modeled employing a mixture-fraction based approach, Eddy dissipation concept (EDC), and refined global finite rate (FR) models. Radiative properties were estimated employing four weighted-sum-of-gray-gases (WSGG) models formulated from different spectroscopic/model databases. The mixture fraction and EDC models correctly predicted the trends in flame length and OH concentration variations, and the O2, CO2, and temperature measurements outside the flames. The refined FR chemistry model predictions of CO2and O2deviated from their measured values in the flame with 50% O2in the oxidizer. Flame radiant power estimates varied by less than 10% between the mixture fraction and EDC models but more than 60% between the different WSGG models. The largest variations were attributed to the postcombustion gases in the temperature range 500 K–800 K in the upper sections of the furnace which also contributed significantly to the overall radiative transfer.

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21

Mardani, Amir. "Optimization of the Eddy Dissipation Concept (EDC) model for turbulence-chemistry interactions under hot diluted combustion of CH4/H2." Fuel 191 (March 2017): 114–29. http://dx.doi.org/10.1016/j.fuel.2016.11.056.

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22

Ghaderi, Mohsen, Maryam Ghodrat, and Jason J. Sharples. "LES Simulation of Wind-Driven Wildfire Interaction with Idealized Structures in the Wildland-Urban Interface." Atmosphere 12, no. 1 (December 25, 2020): 21. http://dx.doi.org/10.3390/atmos12010021.

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This paper presents a numerical investigation of the impact of a wind-driven surface fire, comparable to a large wildfire, on an obstacle located downstream of the fire source. The numerical modelling was conducted using FireFOAM, a coupled fire-atmosphere model underpinned by a large eddy simulation (LES) solver, which is based on the Eddy Dissipation Concept (EDC) combustion model and implemented in the OpenFOAM platform (an open source CFD tool). The numerical data were validated using the aerodynamic measurements of a full-scale building model in the absence of fire effects. The results highlighted the physical phenomena contributing to the fire spread pattern and its thermal impact on the building. In addition, frequency analysis of the surface temperature fluctuations ahead of the fire front showed that the presence of a building influences the growth and formation of buoyant instabilities, which directly affect the behaviour of the fire’s plume. The coupled fire-atmosphere modelling presented here constitutes a fundamental step towards better understanding the behaviour and potential impacts of large wind-driven wildland fires in wildland-urban interface (WUI) areas.

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23

S. Vaid, Hitesh, Kanwar Devesh Singh, Helen H. Lou, Daniel Chen, and Peyton Richmond. "A run time combustion zoning technique towards the EDC approach in large-scale CFD simulations." International Journal of Numerical Methods for Heat & Fluid Flow 24, no. 1 (December 20, 2013): 21–35. http://dx.doi.org/10.1108/hff-09-2011-0190.

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Purpose – This paper aims to present a novel run time combustion zoning (RTCZ) technique based on the working principle of eddy dissipation concept (EDC) for combustion modeling. This technique selectively chooses cells in which the full reaction mechanism needs to be solved. The selection criterion is based on the concept of differentiating between combustion and the non-combustion zone. With this approach, considerable reduction in computational load and stability of the solution was observed and even the number of iterations required to achieve a stable solution was significantly reduced. Design/methodology/approach – Computational fluid dynamics (CFD) simulations of real life combustion problems such as industrial scale flares, fuel fired furnaces and IC engines are difficult due to the strong interactions of chemistry with turbulence as well as the wide range distribution of time and length scales. In addition, comprehensive chemical mechanisms for hydrocarbon combustion may include hundreds of species and thousands of reactions that are known in detail for only a limited number of fuels. Even with the most advanced computers, accurate simulation of these problems is not easy. Hence, the modeler needs to have strategies to either simplify the chemistry or to improve the computational efficiency. Findings – The EDC turbulence model has been widely used for treating the interaction between turbulence and the chemistry in combustion problems. In an EDC model, combustion is assumed to occur in a constant pressure reactor, with initial conditions taken as the concentration of the current species and temperature in the cell. With these assumptions, EDC solves the full or simplified reaction mechanism in all the grid cells at all iterations. Originality/value – This paper presents a novel RTCZ technique for improving the computational efficiency, when the EDC model is used in CFD modeling. Considerable reduction in computational time and stability of the solution can be achieved. It was also observed that the number of iterations required to achieve a converged solution was significantly reduced.

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24

Kuznetsov, V. A., Ar A. Dekterev, I. S. Anufriev, and A. V. Minakov. "Numerical study of the effect of superheated steam supply during the combustion of liquid fuel in a burner on the reduction of harmful emissions." Journal of Physics: Conference Series 2233, no. 1 (April 1, 2022): 012005. http://dx.doi.org/10.1088/1742-6596/2233/1/012005.

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Abstract In this work, the process of combustion of hydrocarbon fuel in the original burner of the evaporative type with the supply of superheated water vapor to the reaction zone is investigated using numerical modeling. N-heptane was used as a model fuel. The turbulent flow of gases was modeled on the basis of the RANS (Reynolds-averaged Navier–Stokes) approach. The combustion was simulated with the EDC (Eddy Dissipation Concept) model using a reduced chemical reaction mechanism. Calculation studies of the effect of steam on the processes occurring in the combustion chamber were carried out. Comparative analysis of the calculation results with experimental data showed good agreement in terms of the main integral parameters. The positive effect of the influence of steam injection into the active combustion zone of hydrocarbon fuel on the reduction of harmful emissions is shown.

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Kuznetsov, V. A., Ar A. Dekterev, I. S. Anufriev, and A. V. Minakov. "Numerical study of the effect of superheated steam supply during the combustion of liquid fuel in a burner on the reduction of harmful emissions." Journal of Physics: Conference Series 2233, no. 1 (April 1, 2022): 012005. http://dx.doi.org/10.1088/1742-6596/2233/1/012005.

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Abstract In this work, the process of combustion of hydrocarbon fuel in the original burner of the evaporative type with the supply of superheated water vapor to the reaction zone is investigated using numerical modeling. N-heptane was used as a model fuel. The turbulent flow of gases was modeled on the basis of the RANS (Reynolds-averaged Navier–Stokes) approach. The combustion was simulated with the EDC (Eddy Dissipation Concept) model using a reduced chemical reaction mechanism. Calculation studies of the effect of steam on the processes occurring in the combustion chamber were carried out. Comparative analysis of the calculation results with experimental data showed good agreement in terms of the main integral parameters. The positive effect of the influence of steam injection into the active combustion zone of hydrocarbon fuel on the reduction of harmful emissions is shown.

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26

Yang, Gelan, Huixia Jin, and Na Bai. "A Numerical Study on Premixed Bluff Body Flame of Different Bluff Apex Angle." Mathematical Problems in Engineering 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/272567.

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In order to investigate effects of apex angle (α) on chemically reacting turbulent flow and thermal fields in a channel with a bluff body V-gutter flame holder, a numerical study has been carried out in this paper. With a basic geometry used in a previous experimental study, the apex angle was varied from 45° to 150°. Eddy dissipation concept (EDC) combustion model was used for air and propane premixed flame. LES-Smagorinsky model was selected for turbulence. The gird-dependent learning and numerical model verification were done. Both nonreactive and reactive conditions were analyzed and compared. The results show that asαincreases, recirculation zone becomes bigger, and Strouhal number increases a little in nonreactive cases while decreases a little in reactive cases, and the increase ofαmakes the flame shape wider, which will increase the chamber volume heat release ratio and enhance the flame stability.

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27

González-Durán, José Eli Eduardo, Marco Antonio Zamora-Antuñano, Leonel Lira-Cortés, Juvenal Rodríguez-Reséndiz, Juan Manuel Olivares-Ramírez, and Néstor Efrén Méndez Lozano. "Numerical Simulation for the Combustion Chamber of a Reference Calorimeter." Processes 8, no. 5 (May 13, 2020): 575. http://dx.doi.org/10.3390/pr8050575.

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This paper focuses on the numerical modeling of the effect of the height of a combustion chamber on the development of a reference calorimeter whose objective is to measure the calorific value of natural gas. The impacts of temperature, velocity, and mass fraction on the exhaust gases were evaluated by varying the height of the combustion chamber. The eddy dissipation concept (EDC) approach was used to model combustion with two different chemical kinetic mechanisms: one with three steps, called the three-step mechanism defined by default in the software used, and second skeletal model, which consists of 41 steps, through the ChemKin-import file with 16 species. The main result of this study is the selection of a combustion chamber height for the reference calorimeter that produces the best performance in the combustion process, which is 70 mm, as well as the main differences in using a three-step mechanism and a skeletal model to simulate an oxy-fuel combustion reaction.

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Li, Jianzhong, Li Yuan, Wei Li, and Kaichen Zhang. "Numerical Investigation of Combustion Characteristics of a Wave Rotor Combustor Based on a Reduced Reaction Mechanism of Ethylene." International Journal of Aerospace Engineering 2018 (November 1, 2018): 1–21. http://dx.doi.org/10.1155/2018/8672760.

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To improve simulations of the flame and pressure wave propagation process and investigate the combustion characteristics of a wave rotor combustor (WRC), direct relation graphs with error propagation (DRGEP), quasi-steady-state assumption (QSSA), and sensitivity analysis were used to establish a reduced reaction mechanism comprised of 23 species and 55 elementary reactions, based on the LLNL N-Butane mechanism. The reduced reaction mechanism of ethylene was combined with an eddy dissipation concept (EDC) model to simulate the flame propagation characteristics in a simplified WRC channel. The effects of spoilers with different blockage ratios and hot-jets of different species on combustion characteristics of flame propagation and pressure rise in the WRC channel were investigated. When the heated inert air was used as hot-jet, the ignition delay time of WRC would increase, which indicated that the activity of the burned gas from the hot-jet igniter would affect the ignition delay time. The spoiler facilitates the coupling of flame and shock waves to reduce the coupling time and distance. With the blockage ratio of the spoiler increasing, the coupling time and distance would be reduced.

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Khlifi, Saaida, Marzouk Lajili, Patrick Perré, and Victor Pozzobon. "A Numerical Study of Turbulent Combustion of a Lignocellulosic Gas Mixture in an Updraft Fixed Bed Reactor." Sustainability 14, no. 24 (December 11, 2022): 16587. http://dx.doi.org/10.3390/su142416587.

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Lignocellulosic biomass is an established source of energy with various applications. Yet, its diversity renders the proper combustion of its thermochemical degradation vapors challenging. In this work, the combustion of syngas obtained from biomass thermochemical conversion was numerically investigated to limit pollutant emission. The Computational Fluid Dynamics (CFD) simulation was performed using the open-source OpenFOAM. The reactor was considered in an axisymmetric configuration. The gas mixture resulting from the pyro-gasification devolatilization was composed of seven species: CO, CO2, H2O, N2, O2, light, and heavy hydrocarbon, represented by methane (CH4) and benzene (C6H6), respectively. The evolutions of mass, momentum, energy, and species’ concentrations were tracked. The flow was modeled using the RANS formulation. For the chemistry, reduced kinetic schemes of three and four steps were tested. Moreover, the Eddy Dissipation Concept (EDC) model was used to account for the turbulence–chemistry interaction. The numerical prediction enabled us to describe the temperature and the species. Results show that all transported variables were closely dependent on the mass flow rate of the inflow gas, the primary and the secondary air injections. Finally, from a process perspective, the importance of the secondary air inlet to limit pollutants emissions can be concluded.

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Arefyev, K. Yu, K. V. Fedotova, A. I. Krikunova, and V. A. Panov. "Mathematical and Physical Simulation of the Cross-Flow Velocity Pulsation Effect on the Flame Structure during the Diffusion Mode of Methane Combustion." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 2 (89) (April 2020): 65–84. http://dx.doi.org/10.18698/1812-3368-2020-2-65-84.

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The paper presents the results of calculation and experimental studies of the diffusion combustion of methane in the air cross-flow. We developed a mathematical model for describing a diffusion air-methane flame, the model being based on solving a system of averaged Navier --- Stokes equations in an unsteady setting. To calculate the combustion processes, we used the flamelet models and eddy dissipation concept (EDC) model. The mathematical model was supplemented by a detailed kinetic mechanism consisting of 325 elementary reactions involving 53 substances. Furthermore, we carried out calculations and comparative analysis of the flame characteristics using various turbulence models: k − ε, k − ω SST and Transition SST. The study introduces a diagram of the experimental setup for physical modeling of methane combustion in the air cross-flow, and presents the results of the calculation and experimental study of the cross-flow velocity pulsation effect on the flame structure, as well as the efficiency of methane combustion in the diffusion mode. We obtained data on temperature and concentration fields at pulsation frequencies of 0--100 Hz. Findings of research show that for the case under consideration, stable combustion occurs at pulsation frequencies of 0--90 Hz. The maximum observed flame lift-off is 3.2 times the diameter of the burner nozzle

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Fortunato, Valentina, Andres Giraldo, Mehdi Rouabah, Rabia Nacereddine, Michel Delanaye, and Alessandro Parente. "Experimental and Numerical Investigation of a MILD Combustion Chamber for Micro Gas Turbine Applications." Energies 11, no. 12 (December 1, 2018): 3363. http://dx.doi.org/10.3390/en11123363.

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In the field of energy production, cogeneration systems based on micro gas turbine cyclesappear particularly suitable to reach the goals of improving efficiency and reducing pollutants.Moderate and Intense Low-Oxygen Dilution (MILD) combustion represents a promising technologyto increase efficiency and to further reduce the emissions of those systems. The present work aims atdescribing the behavior of a combustion chamber for a micro gas turbine operating in MILD regime.The performances of the combustion chamber are discussed for two cases: methane and biogascombustion. The combustor performed very well in terms of emissions, especially CO and NOx,for various air inlet temperatures and air-to-fuel ratios, proving the benefits of MILD combustion.The chamber proved to be fuel flexible, since both ignition and stable combustion could be achievedby also burning biogas. Finally, the numerical model used to design the combustor was validatedagainst the experimental data collected. The model performs quite well both for methane and biogas.In particular, for methane the Partially Stirred Reactor (PaSR) combustion model proved to be thebest choice to predict both minor species, such as CO, more accurately and cases with lower reactivitythat were not possible to model using the Eddy Dissipation Concept (EDC). For the biogas, the mostappropriate kinetic mechanism to properly model the behavior of the chamber was selected

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Yan, C., ZR Wang, F. Jiao, and C. Ma. "Numerical simulation on structure effects for linked cylindrical and spherical vessels." SIMULATION 94, no. 9 (March 21, 2018): 849–58. http://dx.doi.org/10.1177/0037549718763081.

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This paper presents a simulation study on the methane–air mixture explosions through using the eddy-dissipation concept (EDC) model in FLUENT. The aims are to investigate the structure effects of methane–air mixture explosions in a spherical vessel, cylindrical vessel and different systems of cylindrical vessels connected with pipe. Meanwhile, in order to study the characteristics of methane-air mixture explosions in the linked vessels, changes of flame temperature and airflow velocity in the linked vessels are simulated and analyzed. The results suggest that the effect of structural changes of a single vessel on the gas explosion intensity is clear, and the explosion intensity of a spherical vessel is greater than that of a cylindrical vessel. The simulation results of different structural forms of a cylindrical vessel connected with pipelines show that the time to reach the peak value of explosion pressure is the shortest in the linked vessels, and the explosion pressure rising rate is highest at the vessel’s center. For the linked vessels, after ignition, the airflow ahead of the flame propagates to the secondary vessel, and the maximum airflow velocity of every monitoring point in the linked vessels increases. The detonation occurs when the flame propagates to the secondary vessel, which leads to a severe secondary explosion in the secondary vessel. The studies can provide an important reference for the safe design of industrial vessels.

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He, Di, Yusong Yu, Yucheng Kuang, and Chaojun Wang. "Model Comparisons of Flow and Chemical Kinetic Mechanisms for Methane–Air Combustion for Engineering Applications." Applied Sciences 11, no. 9 (April 30, 2021): 4107. http://dx.doi.org/10.3390/app11094107.

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The reasonably accurate numerical simulation of methane–air combustion is important for engineering purposes. In the present work, the validations of sub-models were carried out on a laboratory-scale turbulent jet flame, Sandia Flame D, in comparison with experimental data. The eddy dissipation concept (EDC), which assumes that the molecular mixing and subsequent combustion occur in the fine structures, was used for the turbulence–chemistry interaction. The standard k-ε model (SKE) with the standard or the changed model constant C1ε, the realizable k-ε model (RKE), the shear-stress transport k-ω model (SST), and the Reynolds stress model (RSM) were compared with the detailed chemical kinetic mechanism of GRI-Mech 3.0. Different reaction treatments for the methane–air combustion were also validated with the available experimental data from the literature. In general, there were good agreements between predictions and measurements, which gave a good indication of the adequacy and accuracy of the method and its further applications for industry-scale turbulent combustion simulations. The differences between predictions and measured data might have come from the simplifications of the boundary settings, the turbulence model, the turbulence–reaction interaction, and the radiation heat transfer model. For engineering predictions of methane–air combustion, the mixture fraction probability density function (PDF) model for the partially premixed combustion with RSM is recommended due to its relatively low simulation expenses, acceptable accuracy predictions, and quantitatively good agreement with the experiments.

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D’Amato, Marco, Annarita Viggiano, and Vinicio Magi. "On the Turbulence-Chemistry Interaction of an HCCI Combustion Engine." Energies 13, no. 22 (November 11, 2020): 5876. http://dx.doi.org/10.3390/en13225876.

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A numerical study was carried out to evaluate the influence of engine combustion chamber geometry and operating conditions on the performance and emissions of a homogeneous charge compression ignition (HCCI) engine. Combustion in an HCCI engine is a very complex phenomenon that is influenced by several factors that need to be controlled, such as gas temperature, heat transfer, turbulence and auto-ignition of the gas mixture. An eddy dissipation concept (EDC) combustion model was used to take into account the interaction between turbulence and chemistry. The model assumed that reactions occur in small turbulent structures called fine-scales, whose characteristic lengths and times depend mainly on the turbulence level. The model parameters were slightly modified with respect to the standard model proposed by Magnussen, to correctly simulate the characteristics of the HCCI combustion process. A reduced iso-octane chemical mechanism with 186 species and 914 chemical reactions was employed together with a sub-mechanism for NOx. The model was validated by comparing the results with available experimental data in terms of pressure and instantaneous heat release rate. Two engine chamber geometries with and without a cavity in the piston were considered, respectively. The two engines provided significant differences in terms of fluid-dynamic patterns and turbulence intensity levels in the combustion chamber. The results show that combustion started earlier and proceeded faster for the flat piston, leading to an increase in both the peak pressure and gross indicated mean effective pressure, as well as a reduction of CO and UHC emissions. An additional analysis was performed by considering a case without swirl for the flat-piston case. Such an analysis shows that the swirl motion reduces the time duration of combustion and slightly increases the gross indicated work per cycle.

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35

KJÄLDMAN, L., A. BRINK, and M. HUPA. "Micro Mixing Time in the Eddy Dissipation Concept." Combustion Science and Technology 154, no. 1 (May 2000): 207–27. http://dx.doi.org/10.1080/00102200008947277.

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36

Chen, Z., J. Wen, B. Xu, and S. Dembele. "Large Eddy Simulation of Fire Dynamics with the Improved Eddy Dissipation Concept." Fire Safety Science 10 (2011): 795–808. http://dx.doi.org/10.3801/iafss.fss.10-795.

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37

Ha, Suim, and Chang Bo Oh. "Large Eddy Simulation of Backdraft Using the Eddy Dissipation Concept Combustion Model." Fire Science and Engineering 33, no. 5 (October 31, 2019): 48–54. http://dx.doi.org/10.7731/kifse.2019.33.5.048.

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38

Tobing, Rido Lumban, Wusnah Wusnah, Novi Sylvia, Azhari Azhari, and Nasrul ZA. "Studi akurasi model pembakaran pada terhadap prediksi temperatur pada nyala metana tak pracampur menggunakan CFD." Chemical Engineering Journal Storage 1, no. 1 (August 23, 2021): 42. http://dx.doi.org/10.29103/cejs.v1i1.2849.

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Tidak dapat dipungkiri bahwa pembakaran telah mendorong kamajuan dunia ekonomi dan masyarakat sejak manusia menggunakan api. Selain memberikan manfaat bagi manusia, pembakaran juga menghasilkan kerugian dalam hal emisi gas yang dapat merusak lingkungan.Berbagai upaya telah dilakukan untuk meningkatkan efisiensi pembakaran. Computational Fluid Dynamics( CFD) memainkan peranan penting dan digunakan sebagai alat standar di sebagian besar perusahaan dan industri konsultan. Penelitian ini bertujuan untuk menyelidiki kinerja model pembakaran untuk memprediksi temperatur pada nyala metana menggunakan metode Computational Fluid Dynamics (CFD) dengan beberapa model pembakaran yang tersedia pada Ansys Fluent 2020 R1 yaitu Eddy Dissipation Concept dan Non Premixed Combustion. Hasil dari penelitian ini membuktikan bahwa model pembakaran Eddy Dissipation Concept merupakan model yang terbaik dibandingkan dengan model Non Premixed Combustion.secara kualitatif temperatur model Eddy dissipation Concept yang mendekati nilai data eksperimen, dimana suhu yang dicapai model Eddy dissipation Concept mencapai 1840 K pada posisi sekitar 700 mm atau 0.7 m. Secara kuantitatif model Non premixed Combustion tren grafiknya mengikuti data eksperimen namun puncak tertingginya hanya mencapai 1452 K pada posisi sekitar 540 atau 0.54 m di atas nozzle, sedangkan data eksperimen suhunya mencapai 1816 K pada posisi sekitar 560 mm atau 0.56 m.peneliti berharap hasil dari penelitian ini dapat menjadi masukan kedepannya dalam mensimulasikan pembakaran nyala tak pracampur pada metode Computational Fluid Dynamics (CFD).

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39

Lewandowski, Michał T., and Ivar S. Ertesvåg. "Analysis of the Eddy Dissipation Concept formulation for MILD combustion modelling." Fuel 224 (July 2018): 687–700. http://dx.doi.org/10.1016/j.fuel.2018.03.110.

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40

Romero-Anton, Naiara, Xu Huang, Hesheng Bao, Koldo Martin-Eskudero, Erik Salazar-Herran, and Dirk Roekaerts. "New extended eddy dissipation concept model for flameless combustion in furnaces." Combustion and Flame 220 (October 2020): 49–62. http://dx.doi.org/10.1016/j.combustflame.2020.06.025.

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41

Chen, Zhibin, Jennifer Wen, Baopeng Xu, and Siaka Dembele. "Large eddy simulation of a medium-scale methanol pool fire using the extended eddy dissipation concept." International Journal of Heat and Mass Transfer 70 (March 2014): 389–408. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2013.11.010.

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42

Lysenko, Dmitry A., Ivar S. Ertesvåg, and Kjell Erik Rian. "Numerical Simulations of the Sandia Flame D Using the Eddy Dissipation Concept." Flow, Turbulence and Combustion 93, no. 4 (July 20, 2014): 665–87. http://dx.doi.org/10.1007/s10494-014-9561-5.

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43

Nassiri Toosi, Ali, Mohammadreza Farokhi, and Behrooz Mashadi. "Application of modified eddy dissipation concept with large eddy simulation for numerical investigation of internal combustion engines." Computers & Fluids 109 (March 2015): 85–99. http://dx.doi.org/10.1016/j.compfluid.2014.11.029.

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44

Iqbal, Sohail, Björn Pfeiffelmann, Ali Cemal Benim, and Franz Joos. "Numerical analysis of lifted hydrogen flame." MATEC Web of Conferences 240 (2018): 01014. http://dx.doi.org/10.1051/matecconf/201824001014.

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A numerical analysis of a turbulent lifted H2/N2 flame is presented. As combustion mechanisms, a large spectrum is considered including single-step and two-step, as well as detailed mechanisms. As combustion models, various models are considered that treat turbulence-chemistry interaction in different ways, including the Eddy Dissipation Concept and the Laminar Flamelet Method. For turbulence modelling Reynolds Averaged Numerical Simulation and Large Eddy Simulation approaches are used. Results are compared with measurements.

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45

Lysenko, Dmitry A., and Ivar S. Ertesvåg. "Reynolds-Averaged, Scale-Adaptive and Large-Eddy Simulations of Premixed Bluff-Body Combustion Using the Eddy Dissipation Concept." Flow, Turbulence and Combustion 100, no. 3 (December 12, 2017): 721–68. http://dx.doi.org/10.1007/s10494-017-9880-4.

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46

Parente, Alessandro, Mohammad Rafi Malik, Francesco Contino, Alberto Cuoci, and Bassam B. Dally. "Extension of the Eddy Dissipation Concept for turbulence/chemistry interactions to MILD combustion." Fuel 163 (January 2016): 98–111. http://dx.doi.org/10.1016/j.fuel.2015.09.020.

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47

Sodano, Henry A., Jae-Sung Bae, Daniel J. Inman, and W. Keith Belvin. "Improved Concept and Model of Eddy Current Damper." Journal of Vibration and Acoustics 128, no. 3 (November 3, 2005): 294–302. http://dx.doi.org/10.1115/1.2172256.

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When a conductive material experiences a time-varying magnetic field, eddy currents are generated in the conductor. These eddy currents circulate such that they generate a magnetic field of their own, however the field generated is of opposite polarity, causing a repulsive force. The time-varying magnetic field needed to produce such currents can be induced either by movement of the conductor in the field or by changing the strength or position of the source of the magnetic field. In the case of a dynamic system the conductor is moving relative to the magnetic source, thus generating eddy currents that will dissipate into heat due to the resistivity of the conductor. This process of the generation and dissipation of eddy current causes the system to function as a viscous damper. In a previous study, the concept and theoretical model was developed for one eddy current damping system that was shown to be effective in the suppression of transverse beam vibrations. The mathematical model developed to predict the amount of damping induced on the structure was shown to be accurate when the magnet was far from the beam but was less accurate for the case that the gap between the magnet and beam was small. In the present study, an improved theoretical model of the previously developed system will be formulated using the image method, thus allowing the eddy current density to be more accurately computed. In addition to the development of an improved model, an improved concept of the eddy current damper configuration is developed, modeled, and tested. The new damper configuration adds significantly more damping to the structure than the previously implemented design and has the capability to critically damp the beam’s first bending mode. The eddy current damper is a noncontacting system, thus allowing it to be easily applied and able to add significant damping to the structure without changing dynamic response. Furthermore, the previous model and the improved model will be applied to the new damper design and the enhanced accuracy of this new theoretical model will be proven.

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Choual, Kheireddine, and Redouane Benzeguir. "Simulation of Opposed-Jets Configuration H₂/Air, CH₄/Air." International Letters of Chemistry, Physics and Astronomy 55 (July 2015): 34–46. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.55.34.

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The opposed-jets configuration is very used in industrial systems. The actual practical applications use clean fuels which in stead of classical hydrocarbons. The present work is a numerical simulation of opposed diffusion jets using FLUENT6.3.26. We have compared different turbulence models and combustion models and mechanisms to find which gives the best predictions for this type of flows. We have used methane and hydrogen fuels because they are considered as clean fuels. The comparison between k-ε, k-omega and RSM turbulent models shows that both of k-ε and RSM gives good results. The use of k-ε is more practical because it requires less long time to be implied. The comparison between the combustion models shows that EDC gives more realistic results than eddy dissipation and Finite rate models. In addition, the detailed chemical mechanisms are more adequate to this model. For both methane and hydrogen flames, the detailed mechanisms gives good results and temperatures.

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Choual, Kheireddine, and Redouane Benzeguir. "Simulation of Opposed-Jets Configuration H<sub>2</sub>/Air, CH<sub>4</sub>/Air." International Letters of Chemistry, Physics and Astronomy 55 (July 3, 2015): 34–46. http://dx.doi.org/10.56431/p-b4i802.

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Анотація:

The opposed-jets configuration is very used in industrial systems. The actual practical applications use clean fuels which in stead of classical hydrocarbons. The present work is a numerical simulation of opposed diffusion jets using FLUENT6.3.26. We have compared different turbulence models and combustion models and mechanisms to find which gives the best predictions for this type of flows. We have used methane and hydrogen fuels because they are considered as clean fuels. The comparison between k-ε, k-omega and RSM turbulent models shows that both of k-ε and RSM gives good results. The use of k-ε is more practical because it requires less long time to be implied. The comparison between the combustion models shows that EDC gives more realistic results than eddy dissipation and Finite rate models. In addition, the detailed chemical mechanisms are more adequate to this model. For both methane and hydrogen flames, the detailed mechanisms gives good results and temperatures.

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50

Herrera Múnera, Bernardo Argemiro, Andrés Adolfo Amell Arrieta, and Francisco Javier Cadavid Sierra. "Numerical models for the phenomenological study of flameless combustion." Ingeniería e Investigación 29, no. 2 (May 1, 2009): 70–76. http://dx.doi.org/10.15446/ing.investig.v29n2.15164.

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Flameless combustion is a technique which offers environmental advantages such as lower than 100 ppm NOx and CO emissions due to below 200 K temperature gradients. Flameless combustion also supplies higher than 70% energy efficiency. Knowledge of the phenomena in this combustion regime has been facilitated by using numerical simulation. This paper reviewed the specialised literature about the most commonly used turbulence, combustion, heat transfer and NOx formation models in modelling flameless combustion with CFD codes. The review concluded that the k-ε standard model is the most used for turbulence. Finite rate/eddy dissipation with modified constants and eddy dissipation concept models are suitable for combustion reactions, discrete ordinates and weighted sum gray gas (WSGG) models are used for radiation and thermal, prompt and N2O intermediate models are used for NOx.

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