Combustion and Flame最新文献

{"title":"An experimental and modeling study on the laminar burning velocities of ammonia + oxygen + argon mixtures","authors":"Jundie Chen,&nbsp;Marco Lubrano Lavadera ,&nbsp;Alexander A. Konnov","doi":"10.1016/j.combustflame.2023.112930","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112930","url":null,"abstract":"<div><p>Most often, the laminar burning velocity (S_L) of ammonia was measured in mixtures diluted by nitrogen bearing in mind its potential use as an alternative carbon-free fuel. Replacing the diluent with argon can increase the flame temperature and thus provide additional targets for validating pertinent detailed kinetic models. The S_L data for ammonia + oxygen + argon mixtures are scarce; therefore, in the present study, new measurements have been performed using the heat flux method at an initial temperature of 298 K and atmospheric pressure over an equivalence ratio range of 0.4–1.5. The argon mole percentage in the mixture has been changed from 30 to 60%. Nine recent ammonia kinetic models are selected and validated against these new experimental data, where it is found that the models by Han et al. (Combust. Flame 228 (2021):13), Shrestha et al. (Proc. Combust. Inst. 38 (2021):2163), and Okafor et al. (Combust. Flame 204 (2019):162) provide the best predictions. Further sensitivity analysis showed that the most crucial nitrogen-related reactions for S_L in present flames found in the model of Shrestha et al. are different from the other two, and flux analysis elucidated that the main consumption fluxes of NH₂ radical are different among the three models. The model of Han et al., which is from the authors’ group, was revisited, and the rate constants for three reactions NH₂+H(+M)=NH₃(+M), NNH+O<img>NH+NO, and NH₂+O<img>HNO+H were modified. Available speciation data from shock tube and flame studies are used to select the most suitable rate constants among expressions recommended in the literature. The updated model performs well in reproducing a range of S_L, ignition delay times, and speciation data from a jet-stirred reactor for ammonia + oxygen + argon mixtures.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112930"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3138529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laser-induced breakdown spectroscopy using modulated ns-laser pulses for multi-property measurements in high-pressure combustion environments","authors":"Clemence Rubiella ,&nbsp;Taekeun Yoon ,&nbsp;Seonwoong Kim,&nbsp;Hyungrok Do","doi":"10.1016/j.combustflame.2023.112941","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112941","url":null,"abstract":"<div><p><span>The present work proposes a novel method to improve the calibration accuracy of laser-induced breakdown spectroscopy (LIBS) in high-pressure combustion environments. Typically, optical plasma breakdown suffers from instability in highly pressurized environments, and the plasma emits photons of noisy and broadened spectra that are unusable for extracting quantitative property information. An improved plasma emission spectrum signal is obtained by modulating or chopping the pulse width of a fundamental 10 Hz Nd:YAG laser pulse by limiting the stochastic inverse-Bremsstrahlung (IB) photon absorption process. The modulated pulse duration is decreased from 9.2 ns to 5 ns utilizing a simple optical setup prior to being focused into a high-pressure combustor. In order to evaluate the impact of the modulated temporal laser pulse profile on the plasma emission, </span>Proper Orthogonal Decomposition<span> (POD) is applied to the emission spectra collected over a customized flat flame burner with varied composition and pressure. POD is capable of decomposing property-sensitive spectrum components that determine the accuracy of the spectrum calibration for property measurements using LIBS. The POD-analyzed database comprises 50 flame cases with pressure and equivalence ratios ranging from 1 to 10 bars and 0.7 to 1.1, respectively. Two Reduced-Order Models (ROMs) are trained with the collected spectra; modulated and original pulse, to predict three distinct flame properties; pressure, equivalence ratio, and adiabatic flame temperature. The output model estimates pressure, equivalence ratio and adiabatic flame temperature with an improved accuracy of 8%, 7% and 55%, respectively when the ROM is trained with chopped spectra over the calibrated pressure range. This is because the reduced pulse width in general lowers the signal level of broadband plasma emission that is sensitive to pressure. The POD-aided spectrum analyses suggest that flexible pulse modulation helps to improve the calibration accuracy in a broad gas density range with varied pressure and temperature.</span></p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112941"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3138533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and chemical kinetic modeling study of high-temperature oxidation of diisopropyl methylphosphonate (DIMP) - A sarin simulant","authors":"Ramees K. Rahman ,&nbsp;Chun-Hung Wang ,&nbsp;Artëm E. Masunov ,&nbsp;Subith Vasu","doi":"10.1016/j.combustflame.2023.112878","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112878","url":null,"abstract":"<div><p><span>Chemical warfare (CW) agent simulants are used in laboratory experiments to study the combustion characteristics of CW agents due to their high toxicity. A crucial CW agent simulant with a chemical structure similar to the deadly nerve agent Sarin (GB) is diisopropyl methylphosphonate (DIMP), an organophosphate compound (OPC). In this study, the high-temperature </span>oxidation<span><span> of DIMP is investigated in a shock tube at temperatures between 1440 K and 1710 K and a pressure of 1–2 atm. The carbon monoxide </span>mole fraction time histories near 4.9 µm were obtained using laser absorption spectroscopy. The rate parameters for DIMP's H-abstraction reactions with O, and OH radicals were determined using molecular simulations. The rates of reactions involving smaller phosphorous species were also calculated at the CBS-QB3 level. These reactions along with the isopropanol sub-mechanism from the literature were added to the LLNL model to obtain an improved chemical kinetic mechanism for DIMP. Since isopropanol was a major intermediate in DIMP decomposition, validations were conducted with CO time histories during the oxidation of isopropanol. The new model predicted CO during isopropanol oxidation reasonably well. Both the LLNL model and the model developed in this work could predict CO time histories during DIMP oxidation satisfactorily. To comprehend the CO formation pathways and sensitive reactions during DIMP oxidation, reaction path analysis and sensitivity analysis were also carried out. The reaction mechanism developed here will help in the design, development, and optimization of efficient, effective and secure CW destruction techniques.</span></p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112878"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1634665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A self-consistent extension of flamelet theory for partially premixed combustion","authors":"Hernan Olguin ,&nbsp;Pascale Domingo ,&nbsp;Luc Vervisch ,&nbsp;Christian Hasse ,&nbsp;Arne Scholtissek","doi":"10.1016/j.combustflame.2023.112911","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112911","url":null,"abstract":"<div><p><span><span>Orthogonal coordinate systems represent an attractive alternative for the formulation of two-dimensional composition space equations for partially </span>premixed combustion<span><span>: They avoid the need of closure models for a cross scalar dissipation rate and allow for a direct recovery of the corresponding </span>flamelet equations in the asymptotic limits of non-premixed and premixed combustion. Despite these remarkable features, this kind of coordinate system still presents some important unsolved issues, which have limited their application so far. These difficulties are mainly associated with i) the lack of an appropriate formalism for the definition of two variables having orthogonal gradients in the entire flame domain and ii) the absence of corresponding closure models for the gradients of these variables in two-dimensional composition space. In the present work, it is shown how a Lagrangian interpretation of the flamelet derivative allows solving both problems. More specifically, after the mixture fraction, </span></span><span><math><mi>Z</mi></math></span>, is adopted as first coordinate, the proposed approach allows to derive i) two-dimensional composition space equations for all reactive scalars, ii) a transport equation for a modified reaction progress variable, <span><math><mi>φ</mi></math></span><span>, satisfying the desired orthogonality condition, </span><span><math><mrow><mi>∇</mi><mi>Z</mi><mo>·</mo><mi>∇</mi><mi>φ</mi><mo>=</mo><mn>0</mn></mrow></math></span>, and iii) two-dimensional composition space equations for <span><math><mrow><msub><mi>g</mi><mi>Z</mi></msub><mo>=</mo><mrow><mo>|</mo><mi>∇</mi><mi>Z</mi><mo>|</mo></mrow></mrow></math></span> and <span><math><mrow><msub><mi>g</mi><mi>φ</mi></msub><mo>=</mo><mrow><mo>|</mo><mi>∇</mi><mi>φ</mi><mo>|</mo></mrow></mrow></math></span>. The obtained set of two-dimensional equations in orthogonal composition space is general and it can describe different flames of interest. In order to illustrate the capabilities of the formulation, the equations are then specialized for planar flames with unity Lewis number, obtaining in this way a solvable set of composition space equations in orthogonal coordinates. After an appropriate numerical approach is introduced, the resulting 2D equations are solved to analyze the interaction between premixed flamelets with a strain rate prescribed along the <span><math><mi>Z</mi></math></span><span>-dimension controlling the interaction. Both flame structures and budgets of the scalar gradient equations are studied and the results provide new insights into the physics of scalar gradients in two-dimensional composition space. Finally, conceivable coupling strategies of the present formulation with CFD codes for the simulation of turbulent flames are discussed.</span></p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112911"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1749397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of CO2 dilution on structures of premixed syngas/air flames in a gas turbine model combustor","authors":"F. Pignatelli ,&nbsp;S. Derafshzan ,&nbsp;D. Sanned ,&nbsp;N. Papafilippou ,&nbsp;R.Z. Szasz ,&nbsp;M.A. Chishty ,&nbsp;P. Petersson ,&nbsp;X.-S. Bai ,&nbsp;R. Gebart ,&nbsp;A. Ehn ,&nbsp;M. Richter ,&nbsp;D. Lörstad ,&nbsp;A.A. Subash","doi":"10.1016/j.combustflame.2023.112912","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112912","url":null,"abstract":"<div><p>The impact of CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> dilution on combustion of syngas (a mixture of H<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span>, CO, and CH<span><math><msub><mrow></mrow><mn>4</mn></msub></math></span>) was investigated in a lab-scale gas turbine model combustor at atmospheric pressure conditions. Two mild dilution levels of CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span>, corresponding to 15% and 34% of CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> mole fraction in the syngas/CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> mixtures, were experimentally investigated to evaluate the effects of CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> dilution on the flame structures and the emissions of CO and NO<span><math><mi>x</mi></math></span>. All experiments were performed at a constant Reynolds number (Re = 10000). High-speed flame luminescence, simultaneous planar laser-induced fluorescence (PLIF) measurements of the OH radicals and particle image velocimetry (PIV) were employed for qualitative and quantitative assessment of the resulting flame and flow structures. The main findings are: (a) the operability range of the syngas flames is significantly affected by the CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> dilution, with both the lean blowoff (LBO) limit and the flashback limit shifting towards fuel-richer conditions as the CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> dilution increases; (b) syngas flames exhibit flame-pocket structures with chemical reactions taking place in isolated pockets surrounded by non-reacting fuel/air mixture; (c) the inner recirculation zone tends to move closer to the burner axis at high CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> dilution, and (d) the NO<span><math><mi>x</mi></math></span> emission becomes significantly lower with increasing CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> dilution while the CO emission exhibits the opposite trend. The flame-pocket structure is more significant with increased CO<span><math><msub><mrow></mrow><mn>2</mn></msub></math></span> dilution level. The low NO<span><math><mi>x</mi></math></span> emissions and high CO emissions are the results of the flame-pocket structures.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112912"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3450714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of flamelet manifolds for turbulent flame-wall interactions in large-eddy simulations","authors":"Yujuan Luo,&nbsp;Matthias Steinhausen,&nbsp;Driss Kaddar,&nbsp;Christian Hasse,&nbsp;Federica Ferraro","doi":"10.1016/j.combustflame.2023.112923","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112923","url":null,"abstract":"<div><p>A turbulent side-wall quenching (SWQ) flame in a fully developed channel flow is studied using Large-Eddy Simulation (LES) with a tabulated chemistry approach. Three different flamelet<span> manifolds with increasing levels of complexity are applied: the Flamelet-Generated Manifold (FGM) considering varying enthalpy levels, the Quenching Flamelet-Generated Manifold (QFM), and the recently proposed Quenching Flamelet-Generated Manifold with Exhaust Gas Recirculation<span><span> (QFM-EGR), with the purpose being to assess their capability to predict turbulent flame-wall interactions (FWIs), which are highly relevant to numerical simulations of real devices such as gas turbines and </span>internal combustion engines.</span></span></p><p>The accuracy of the three manifolds is evaluated and compared a posteriori, using the data from a previously published flame-resolved simulation with detailed chemistry for reference. For LES with the FGM, the main characteristics such as the mean flow field, temperature, and major species can be captured well, while notable deviations from the reference results are observed for the near-wall region, especially for pollutant species such as CO. In accordance with the findings from laminar FWI, improvement is also observed in the simulation with QFM under turbulent flow conditions. Although LES with the QFM-EGR shows a similar performance in the prediction of mean quantities as LES with QFM, it presents significantly better agreement with the reference data regarding instantaneous thermo-chemical states near the quenching point. This indicates the necessity to take into account the mixing effects in the flamelet manifold to correctly capture the flame-vortex interaction near the flame tip in turbulent configurations. Based on the findings from this study, suitable flamelet manifolds can be chosen depending on the aspects of interest in practical applications.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112923"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"2700577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A computationally efficient approach for soot modeling with discrete sectional method and FGM chemistry","authors":"Abhijit Kalbhor ,&nbsp;Daniel Mira ,&nbsp;Jeroen van Oijen","doi":"10.1016/j.combustflame.2023.112868","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112868","url":null,"abstract":"<div><p>A novel approach for the prediction of soot formation in combustion simulations within the framework of discrete sectional method (DSM) based univariate soot model and Flamelet Generated Manifold (FGM) chemistry, referred to as FGM-CDSM, is proposed in this study. The FGM-CDSM considers the clustering of soot sections derived from the original soot particle size distribution function (PSDF) to minimize the computational cost. Unlike conventional DSM, in FGM-CDSM, governing equations for soot mass fractions are solved for the clusters, by using a pre-computed lookup table with tabulated soot source terms from the flamelet manifold, while the original soot PSDF is re-constructed in a post-processing stage. The flamelets employed for the manifold are computed with detailed chemistry and the complete sectional soot model. A comparative assessment of FGM-CDSM is conducted in laminar diffusion flames for its accuracy and computational performance against the detailed kinetics-based classical sectional model. Numerical results reveal that the FGM-CDSM can favorably reproduce the global soot quantities and capture their dynamic response predicted by detailed kinetics with a good qualitative agreement. Furthermore, compared to detailed kinetics, FGM-CDSM is shown to substantially reduce the computational cost of the complete reacting flow simulation with soot particle transport. Primarily, the use of FGM reduces the overall calculation by about two orders of magnitude compared to detailed kinetics, which is advanced further with the clustering of sections at a low memory footprint. Therefore, the present work demonstrates the promising capabilities of FGM-CDSM in the context of computationally efficient soot calculations and provides an excellent framework for extending its application to the simulations of turbulent sooting flames.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112868"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3137714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding the ignition behaviors of AZ80 magnesium alloy plates based on the experiments and numerical simulations","authors":"S. Ma ,&nbsp;D. Han ,&nbsp;C. Zhang ,&nbsp;J. Zhang ,&nbsp;J.F. Huang ,&nbsp;H.X. Li","doi":"10.1016/j.combustflame.2023.112888","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112888","url":null,"abstract":"<div><p><span>In this paper, the ignition behaviors of AZ80 magnesium alloy plates were studied by experimental observation and numerical analysis. From the experimental tests, it is shown that the ignition process of this alloy can fit very well with model Ⅲ proposed by A. L. Breiter. There exists the obvious difference in the starting </span>ignition time<span><span><span> for the AZ80 alloy plates with different size. The larger the size of the alloy plates, the longer the ignition time. Simulation results confirm an excellent agreement with the </span>ignition temperature<span> rise curve measured in this study. Based on the simulation results, the effects of the size of alloy plates, melting phase change, and the strain of oxidation layers on the internal energy of the system, the ignition time and </span></span>ignition point of the alloys are also investigated in details. This study provides the deep understanding on the start-up process of ignition behaviors for the magnesium alloys.</span></p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112888"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3137716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A detailed chemical kinetic mechanism of 1,1-diamino-2,2-dinitroethylene (FOX-7) initial decomposition in the gas phase","authors":"Jie-Yao Lyu ,&nbsp;Qiren Zhu ,&nbsp;Xin Bai ,&nbsp;Xuan Ren ,&nbsp;Jing Li ,&nbsp;Dongping Chen ,&nbsp;Vitaly G. Kiselev ,&nbsp;Yang Li ,&nbsp;Wenming Yang","doi":"10.1016/j.combustflame.2023.112877","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112877","url":null,"abstract":"<div><p><span>1,1-Diamino-2,2-dinitroethylene (FOX-7 or DADNE) is a promising ingredient of the low-vulnerability propellants. However, one of the major concerns in its further development and applications is the lack of detailed kinetic mechanism for its initial decomposition in the gas phase. In this study, a detailed chemical kinetic mechanism consisting of 38 species and 131 reactions was developed to describe the initial decomposition process<span> of FOX-7. At first, a comprehensive reaction network was established with the aid of reactive molecular dynamics (MD) simulation. Then, the potential energy surfaces (PES) for both unimolecular and bimolecular reactions were identified at the QCISD(T)/CBS//M062X/6-311++G(d,p) level of theory. The rate coefficients were obtained by solving RRKM/ME, and the thermochemical properties of relevant species were calculated at CBS-APNO/G3/G4 levels with the atomization method. Finally, these kinetic and thermochemistry data were processed into a kinetic mechanism and used to simulate the initial decomposition process of FOX-7. The results demonstrated that the H-atom transfer to the beta carbon atom (enamino-imino isomerization) followed by the nitro group elimination dominates the initial decomposition, and the reaction FOX-7 = R3a + NO</span></span>₂ becomes the most significant one under high temperatures (<em>Channel C3</em>). Besides, bimolecular reactions also play a role as the decomposition goes on. Overall, this work provides quantitative predictions of the reaction pathways of gas-phase FOX-7 initial decomposition, and it would serve as a solid foundation for the development of a fully detailed combustion kinetic mechanism for FOX-7.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112877"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3137717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the boundary-layer flashback of premixed hydrogen-enriched swirling flames at high pressures","authors":"Shiming Zhang ,&nbsp;Zhen Lu ,&nbsp;Yue Yang","doi":"10.1016/j.combustflame.2023.112900","DOIUrl":"https://doi.org/10.1016/j.combustflame.2023.112900","url":null,"abstract":"<div><p>We model the boundary-layer flashback (BLF) of <span><math><mrow><msub><mtext>CH</mtext><mn>4</mn></msub></mrow></math></span>/<span><math><mrow><msub><mi>H</mi><mn>2</mn></msub></mrow></math></span><span>/air swirling flames via large-eddy simulations with the flame-surface-density method (LES-FSD), in particular, at high pressures. A local displacement speed model tabulating the stretched flame speed is employed to account for the thermo-diffusive effects, flame surface curvature, and heat loss in LES-FSD. The LES-FSD well captures the propagation characteristics during the BLF of swirling flames. In the LES-FSD for lean </span><span><math><mrow><msub><mtext>CH</mtext><mn>4</mn></msub></mrow></math></span>/<span><math><mrow><msub><mi>H</mi><mn>2</mn></msub></mrow></math></span><span>/air flames at 2.5 bar, the critical equivalence ratio for flashback decreases with the increasing hydrogen volume fraction, consistent with the experiments. This is due to the improved modeling of effects of the flame stretch and heat loss on the local displacement speed. We also develop a simple model to predict the BLF limits of swirling flames. The model estimates the critical bulk velocity for given reactants and swirl number, via the balance between the flame-induced pressure rise and adverse pressure for boundary-layer separation. We validate the model against 14 datasets of </span><span><math><mrow><msub><mtext>CH</mtext><mn>4</mn></msub></mrow></math></span>/<span><math><mrow><msub><mi>H</mi><mn>2</mn></msub></mrow></math></span>/air swirling flame experiments, with the hydrogen volume fractions in fuel from 50% to 100%. The present model well estimates the flashback limits in various operating conditions.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"255 ","pages":"Article 112900"},"PeriodicalIF":4.4,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"1516267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}