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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...
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... Flame D from the Sandia/TNF workshop, as shown schematically in Figure 1, is a piloted methane-air diffusion flame [40][41][42]. The central main jet consists of a methane-air mixture (with 25% by volume of CH 4 ) corresponding to an equivalence ratio of 3.174. ...
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... CFD simulations of Flame D were conducted on an axisymmetric numerical mesh. Though not shown in Figure 1, the following four meshes were used for comparison: A: 49 × 50; B: 157 × 71; C: 202 × 88; and D: 252 × 118. All the meshes gave very close results, and either could be used to produce a grid-independent solution. ...
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... the meshes gave very close results, and either could be used to produce a grid-independent solution. However, the finer mesh (mesh C, 202 × 88 shown in Figure 1) with finer grids in the areas of the jet and the pilot was selected and used in all the simulations even though other grids could be used for this 2D steady work. Considering the model selections were for the engineering methane-air combustion, a much finer mesh was unnecessary. ...
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... profiles of major species from these seven cases are presented in Figures 10-14 for the mass fractions of CH 4 , O 2 , H 2 O, CO 2 , and N 2 , respectively. The mean CH 4 composition profiles along the axis and along the radius @ x/d = 7.5 and 30 are shown and compared with experiments in Figure 10 for the Sandia Flame D with different reaction mechanisms. ...
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... profiles of major species from these seven cases are presented in Figures 10-14 for the mass fractions of CH 4 , O 2 , H 2 O, CO 2 , and N 2 , respectively. The mean CH 4 composition profiles along the axis and along the radius @ x/d = 7.5 and 30 are shown and compared with experiments in Figure 10 for the Sandia Flame D with different reaction mechanisms. The mean O 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 11. ...
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... mean CH 4 composition profiles along the axis and along the radius @ x/d = 7.5 and 30 are shown and compared with experiments in Figure 10 for the Sandia Flame D with different reaction mechanisms. The mean O 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 11. The mean H 2 O composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 12. ...
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... mean O 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 11. The mean H 2 O composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 12. The mean CO 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 13. ...
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... mean H 2 O composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 12. The mean CO 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 13. The mean N 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 14. ...
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... mean CO 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 13. The mean N 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 14. Deviations of predicted and measured values are shown in Table 5 for different combustion models with the RSM model the major species, where the largest deviation happened to the peak values of the O 2 mass fraction shown in Figure 11a. ...
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... mean N 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 14. Deviations of predicted and measured values are shown in Table 5 for different combustion models with the RSM model the major species, where the largest deviation happened to the peak values of the O 2 mass fraction shown in Figure 11a. The minimum O 2 mass fraction profiles shown in Figure 11a were acceptable with the exception of a little shifting towards the burner. ...
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... of predicted and measured values are shown in Table 5 for different combustion models with the RSM model the major species, where the largest deviation happened to the peak values of the O 2 mass fraction shown in Figure 11a. The minimum O 2 mass fraction profiles shown in Figure 11a were acceptable with the exception of a little shifting towards the burner. Again, all the predictions by the EDCs agreed very well with each other. ...
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... best agreement with the experiments among the seven cases for the profiles of major species, with the exception of CH 4 , was reached by the PDF model. The predicted composition profiles of the reactant mass fractions of CH 4 and O 2 , shown in Figures 10 and 11, were lower than the experiments and those of the product mass fractions of H 2 O and CO 2 were larger (as shown in Figures 12 and 13), indicating that combustion progressed faster than that in the experiment. The CH 4 composition profiles from the PDF model, shown in Figure 10, suggested a small amount of CH 4 re-formation close to the axis. ...
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... best agreement with the experiments among the seven cases for the profiles of major species, with the exception of CH 4 , was reached by the PDF model. The predicted composition profiles of the reactant mass fractions of CH 4 and O 2 , shown in Figures 10 and 11, were lower than the experiments and those of the product mass fractions of H 2 O and CO 2 were larger (as shown in Figures 12 and 13), indicating that combustion progressed faster than that in the experiment. The CH 4 composition profiles from the PDF model, shown in Figure 10, suggested a small amount of CH 4 re-formation close to the axis. ...
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... predicted composition profiles of the reactant mass fractions of CH 4 and O 2 , shown in Figures 10 and 11, were lower than the experiments and those of the product mass fractions of H 2 O and CO 2 were larger (as shown in Figures 12 and 13), indicating that combustion progressed faster than that in the experiment. The CH 4 composition profiles from the PDF model, shown in Figure 10, suggested a small amount of CH 4 re-formation close to the axis. Due to the over-predicted mixing and diffusion of the jets, the data close to the axis were smaller than those of the experiments shown in Figure 10c. ...
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... CH 4 composition profiles from the PDF model, shown in Figure 10, suggested a small amount of CH 4 re-formation close to the axis. Due to the over-predicted mixing and diffusion of the jets, the data close to the axis were smaller than those of the experiments shown in Figure 10c. The formation of H 2 O by the EDCs was earlier than in the experiments, as shown in Figure 12a with quantitative agreement and a little over-predicted peak. ...
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... to the over-predicted mixing and diffusion of the jets, the data close to the axis were smaller than those of the experiments shown in Figure 10c. The formation of H 2 O by the EDCs was earlier than in the experiments, as shown in Figure 12a with quantitative agreement and a little over-predicted peak. Almost all the radial predictions of H 2 O were larger than the experiments at x/d = 30, as shown in Figure 12c, meaning that the combustion was intensive at this place with a very similar shape of the temperature, as shown in Figure 7c. ...
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... formation of H 2 O by the EDCs was earlier than in the experiments, as shown in Figure 12a with quantitative agreement and a little over-predicted peak. Almost all the radial predictions of H 2 O were larger than the experiments at x/d = 30, as shown in Figure 12c, meaning that the combustion was intensive at this place with a very similar shape of the temperature, as shown in Figure 7c. Other major composition profiles had similar distributions of the composition of H 2 O, as shown in Figure 11 for O 2 and Figure 13 for CO 2 . ...
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... all the radial predictions of H 2 O were larger than the experiments at x/d = 30, as shown in Figure 12c, meaning that the combustion was intensive at this place with a very similar shape of the temperature, as shown in Figure 7c. Other major composition profiles had similar distributions of the composition of H 2 O, as shown in Figure 11 for O 2 and Figure 13 for CO 2 . The inert N 2 composition profiles, shown in Figure 14, agreed quantitatively well with the experiments. ...
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... all the radial predictions of H 2 O were larger than the experiments at x/d = 30, as shown in Figure 12c, meaning that the combustion was intensive at this place with a very similar shape of the temperature, as shown in Figure 7c. Other major composition profiles had similar distributions of the composition of H 2 O, as shown in Figure 11 for O 2 and Figure 13 for CO 2 . The inert N 2 composition profiles, shown in Figure 14, agreed quantitatively well with the experiments. ...
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... major composition profiles had similar distributions of the composition of H 2 O, as shown in Figure 11 for O 2 and Figure 13 for CO 2 . The inert N 2 composition profiles, shown in Figure 14, agreed quantitatively well with the experiments. Once again, all the N 2 predictions by the EDCs agreed very well with each other, and the best results were from the PDF model. ...
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... composition profiles of minor species of the mass fractions of H 2 , CO, and OH from these seven cases are presented in Figures 15-17, respectively, and the deviations of predicted and measured values are shown in Table 5 for different combustion models with the RSM model. The mean H 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 15 for the Sandia Flame D with different reaction mechanisms. ...
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... composition profiles of minor species of the mass fractions of H 2 , CO, and OH from these seven cases are presented in Figures 15-17, respectively, and the deviations of predicted and measured values are shown in Table 5 for different combustion models with the RSM model. The mean H 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 15 for the Sandia Flame D with different reaction mechanisms. The mean CO composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 16. ...
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... mean H 2 composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 15 for the Sandia Flame D with different reaction mechanisms. The mean CO composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 16. The mean OH composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 17. ...
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... mean CO composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 16. The mean OH composition profiles along the axis and along the radius @ x/d = 7.5, 30, and 45 are shown and compared with experiments in Figure 17. Small differences were found from the predictions by the EDCs for the composition profiles of minor species. ...
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... the profiles of the minor species, such as OH, it should also be noted that the choice of the chemical reaction modelling also affected the prediction of the formation and peak values. The predictions of the minor species, H 2 , CO, and OH, are shown and compared in Figures 15-17 and Table 5. The prediction of OH in any combustion simulation is particularly challenging due to the strong nonlinearity of the species' evolution [79]. ...
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... results, shown in Figures 6-14 and Table 5, indicated that the EDCs could give relatively good predictions for the turbulent piloted methane-air diffusion flame of the Sandia Flame D. For the simulations of industry-scale natural gas combustion furnaces, relative simpler chemical kinetic mechanism and lesser computational costs, such as shown by EDC-21 or EDC-24, could be used for combustion simulations at affordable expenses. Since the result of EDC-21 was quantitatively closest to that of EDC-53, as clearly shown in Figures 6-14, EDC-21 could be used for the simulation of the turbulent piloted methane-air diffusion flame, the Sandia Flame D. With more validations, EDC-21 might be used for simulations in engineering applications. On the other hand, most of the results by the PDF model with lesser simulation expenses than EDC-21, as shown in Figures 6-14, agreed better with the experiments. ...
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... the result of EDC-21 was quantitatively closest to that of EDC-53, as clearly shown in Figures 6-14, EDC-21 could be used for the simulation of the turbulent piloted methane-air diffusion flame, the Sandia Flame D. With more validations, EDC-21 might be used for simulations in engineering applications. On the other hand, most of the results by the PDF model with lesser simulation expenses than EDC-21, as shown in Figures 6-14, agreed better with the experiments. However, NO composition was not included in the EDCs with exceptions of EDC-53 and EDC-49. ...
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... the emission of NO has to be predicted during the turbulent methane-air combustion, an NO x sub-model (implemented in most commercial CFD codes) could be used after validation. Therefore, the PDF model is suggested for simulations of the engineering applications of methane-air combustion based on the results shown in Figures 6-14 and the deviations shown in Table 5. ...
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... In 2D, the RSM approach requires solving a transport equation for four distinct components of the Reynolds stress tensor . The choice of this turbulence model is motivated by three factors: a) literature shows that RSM models yield better agreement of numerical results and experimental data for the Sandia flame D than 2-equation eddy viscosity models [68]; b) the RSM model with baseline equation has shown to be the best trade-off of numerical stability and solution accuracy when modeling the cold flow of the industrial burner under consideration [40]; and c) in contrast with 2-equation turbulence models, RSM allows modeling turbulence anisotropy and thus obtaining improved predictions in complex problems such as those with significant swirl levels [69][70][71]. This is an important factor for burner design optimization, as the swirl intensity in burners has been shown to significantly affect and potentially reduce the formation of NO x [37]. ...
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