Combustion and Flame最新文献

{"title":"Synchrotron vacuum ultraviolet photoionization mass spectrometry to examine low temperature oxidation chemistry of n-heptane under different fuel concentrations and pressures","authors":"Weiye Chen ,&nbsp;Bingzhi Liu ,&nbsp;Hao Lou ,&nbsp;Bin Dong ,&nbsp;Cheng Xie ,&nbsp;Jiuzhong Yang ,&nbsp;Long Zhu ,&nbsp;Zhandong Wang","doi":"10.1016/j.combustflame.2024.113898","DOIUrl":"10.1016/j.combustflame.2024.113898","url":null,"abstract":"<div><div>The study of low temperature oxidation provides valuable insight into the development of low temperature combustion (LTC) engines. Fuel concentration and pressure are the keys to controlling reaction activities, significantly influencing low temperature oxidation behavior. Understanding the effects of these parameters is important to develop and improve the kinetic models, however, the impact of fuel concentration and pressure is rarely examined in the low temperature oxidation process of hydrocarbons. In this work, <em>n</em>-heptane oxidation, with initial fuel mole fractions of 0.1 %, 0.25 % and 0.5 % and pressures of one, five and ten bar, was examined at 440–800 K. The goal was to investigate the influence of these key parameters on <em>n</em>-heptane low temperature oxidation. First, reactivity and formation of products was promoted by increasing the initial fuel concentration; there was a threshold for the initial fuel concentration, and reactions occurred only when it was higher than the threshold at a fixed pressure and residence time. However, the model in the literature was unable to capture this phenomenon. Species profiles were compared with the prediction of the kinetic model in the literature at three initial fuel concentrations and pressures; simulation results were verified, and the different pressure effects on product formation were observed. A preliminary analysis of the reaction mechanism was conducted using the kinetic model for clarification of the pressure effects. Finally, the selectivity of products under one and ten bar was revealed. In general, hydroperoxides and carboxylic acids, etc., displayed positive selectivity, while olefins and cyclic ethers, etc., showed negative selectivity at high pressures.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113898"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103026","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 novel method of efficiently using the experimental data for mechanism optimization: Theory and application to NH3/H2 combustion","authors":"Kexiang Guo ,&nbsp;Rui Fu ,&nbsp;Chun Zou ,&nbsp;Wenyu Li ,&nbsp;Weijia Shen","doi":"10.1016/j.combustflame.2024.113886","DOIUrl":"10.1016/j.combustflame.2024.113886","url":null,"abstract":"<div><div>In this work, a novel method of efficiently using the experimental data (EUED) is proposed to reduce the computational cost of evaluating the objective function. The EUED method involves splitting the full experimental dataset into several subsets that retain the essential features of the full dataset's effects on the influential reactions, with these subsets used in rotation during the iterations. The constraint probability density function (PDF) of the constraint frequency distribution spectrum of the influential reactions reflects the essential features of the experimental data's effects. Thus, the subsets should meet 2 criteria: first, the union of all subsets must equal the full dataset; second, the PDF of the frequency spectrum of the influential reactions in any subset should align with that of the full dataset. A strategy for allocating data into several subsets is proposed. An optimized NH₃ combustion model was developed using the EUED method. The prediction errors are 1.22 for species concentrations during pyrolysis, 1.67 for ST-IDT, 1.45 for species concentrations during oxidation, 1.84 for LBV, and 4.29 for RCM-IDT measurements, respectively. The 200 ST-IDT measurements, 911 LBV measurements and 172 RCM-IDT measurements are split into 4, 10 and 4 subsets, respectively. This approach reduces the computational costs of evaluating the objective function at each iteration by about 80 % during the NH₃ model optimization. The roles of the unimolecular decomposition reactions of NH₃, 2 H-abstraction reactions of NH_i by H and 4 reactions involving NH_i in NH₃ pyrolysis were discussed in detail. The optimization automatically weighs the rate constants of the 7 important reactions in an extraordinarily tangled and complicated reaction network, leading to satisfactory predictions of the NH₃, NH₂ and NH profiles.</div></div><div><h3>Novelty and Significance Statement</h3><div>In this work, a novel method of efficiently using the experimental data (EUED) is proposed to reduce the computational cost of evaluating the objective function. The idea of the EUED method is that the full experimental dataset is split into several subsets which remain the essential feature of the effects of full experimental data on the influential reactions, and the several subsets are used in rotation in the iteration. An optimized NH₃ combustion model was obtained using the EUED method with reducing 80 % computational costs of evaluating the objective function. The optimized NH₃ model outperforms the initial one and the models considered in this work.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113886"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102429","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":"Ignition and flame development of high-pressure liquid ammonia spray combustion with simultaneous high-speed OH* and NH2* chemiluminescence imaging","authors":"Haoqing Wu,&nbsp;Yong Qian,&nbsp;Tianhao Zhang,&nbsp;Jizhen Zhu,&nbsp;Xingcai Lu","doi":"10.1016/j.combustflame.2024.113899","DOIUrl":"10.1016/j.combustflame.2024.113899","url":null,"abstract":"<div><div>Liquid ammonia, benefiting from its convenient storage and high hydrogen content, has gained widespread attention as a carbon-free fuel for combustion devices to achieve carbon emission reduction. In this study, the ignition and flame development characteristics of liquid ammonia spray flame are analyzed with simultaneous high-speed OH*, NH₂* chemiluminescence and flame luminosity imaging. The test is conducted at the ambient pressure of 3 MPa, the ambient temperature of 950 K, and the injection pressure of 40 MPa. The results revealed that liquid ammonia spray flame can be divided into four stages: 1) the ignition process with the appearance of auto-ignition kernels at the jet front; 2) the flame propagation process with auto-ignition kernels expanding to the central spray region; 3) the fully-developed combustion process with the flame filling the core region; 4) the post-combustion process with the flame area decreasing rapidly. OH* signals were first observed at the jet front, and NH₂* signals were observed after OH* signals appeared in aggregated form. Throughout the combustion process, OH* had a wide distribution and a long duration, while the NH₂* not only appeared later but dissipated earlier, and the distribution was smaller than the OH*. Chemical kinetic analysis showed that the primary elementary reactions to produce OH at the ignition moment were O+H₂O=2OH, H+O₂=OH+O, and H₂+O=H+OH, while NH₂ was mainly formed through NH₃+OH=NH₂+H₂O. It was worth noting that after the combustion end, sporadic flames and NH₂* signals can still be observed in the jet region.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113899"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102432","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":"An experimental speciation study of DME, OME1, and OME2 in a single-pulse shock tube at high pressures","authors":"Fabian Lindner ,&nbsp;Marina Braun-Unkhoff ,&nbsp;Clemens Naumann ,&nbsp;Torsten Methling ,&nbsp;Markus Köhler ,&nbsp;Uwe Riedel","doi":"10.1016/j.combustflame.2024.113883","DOIUrl":"10.1016/j.combustflame.2024.113883","url":null,"abstract":"<div><div>The pyrolysis of dimethyl ether (DME), oxymethylene ether-1 (OME₁), and oxymethylene ether-2 (OME₂) and their oxidation with oxygen under three different equivalence ratios (<em>φ</em> = 0.5, 1.0, and 2.0) have been studied experimentally in a customized single-pulse shock tube. The measurements were carried out highly diluted in argon over a wide temperature range between 975 K and 1400 K at initial pressures behind reflected shock waves <em>p</em>₅(<em>t</em> = 0) of about 16 bar. The classical single-pulse mode involving a dump tank was not employed. Instead, post-shock gas samples were extracted through a fast-acting solenoid valve located inside the end flange of the driven section of the shock tube, to reduce measurement errors from thermal boundary layers. Thirteen stable species were identified and quantified by three different gas chromatographs simultaneously, in detail, DME, OME₁, OME₂, methane, ethane, ethene, acetylene, carbon monoxide, carbon dioxide, molecular hydrogen, formaldehyde, methanol, and methyl formate. The temperature dependent, measured, and normalized species concentration profiles were compared with the predicted species profiles obtained by using two different chemical kinetic reaction mechanisms from the literature and an updated version of the in-house reaction model DLR Concise. In addition, speciation data of 1,1,1-trifluoroethane and nitrous oxide at elevated pressures are presented, which were used as external chemical thermometers to validate the calculated temperature behind the reflected shock wave of the single-pulse shock tube.</div></div><div><h3>Novelty and Significance</h3><div>In this work, a series of more than 300 single-pulse shock tube experiments have been performed, to investigate the decomposition products of oxygenated fuels at pressures around 16 bar. To the best of our knowledge, no speciation data is yet available for this pressure regime. By comparing the data with chemical-kinetic reaction mechanisms from the literature, opportunities for model improvement have been identified, particularly regarding methanol formation, which could be further developed in the future.</div><div>The presented high-pressure validation data contributes to the development of chemical-kinetic reaction models for new oxygenated fuels derived from renewable sources. By incorporating these reaction mechanisms into CFD codes, advancements in combustors and engine technology are facilitated, promoting cleaner combustion processes.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113883"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The measurement of turbulent burning velocities of methane-hydrogen-air mixtures at elevated pressures in a spherical vessel","authors":"Marwaan Al-Khafaji ,&nbsp;Junfeng Yang ,&nbsp;Alison S. Tomlin ,&nbsp;Harvey M. Thompson ,&nbsp;Gregory de Boer ,&nbsp;Kexin Liu","doi":"10.1016/j.combustflame.2024.113907","DOIUrl":"10.1016/j.combustflame.2024.113907","url":null,"abstract":"<div><div>Few previous experimental studies have focused on pre-mixed turbulent burning velocities (<em>u_t</em>) for hydrogen/air and methane/hydrogen/air mixtures, especially at the high-pressure conditions most relevant to gas turbine applications. This work employed a Schlieren technique to measure flame speeds for such mixtures in a spherical stainless steel combustion vessel, from which turbulent burning velocities were derived. The hydrogen volume fractions in methane were 30, 50, 70 and 100%. The initial pressures were 0.1, 0.5 and 1.0 MPa, and the initial temperatures were 303 and 360 K. The equivalence ratio (ϕ) was varied between 0.5 and 2 for pure hydrogen and from 0.8 to 1.2 for methane/hydrogen mixtures. The root mean square (rms) turbulent velocity (<em>u’</em>) was varied from 2.0 to 10.0 ms⁻¹. The objectives of this study are: (a) to present an extensive experimental database of turbulent burning velocities for these mixtures over a wide range of conditions; (b) to establish a new correlation for <em>u_t</em> for a flame with Lewis numbers, <em>Le,</em> not equal to unity, and (c) to quantify the dependence of turbulent burning velocity on pressure, temperature, stretch rate, laminar flame instability and rms velocity. As the pressure increased, the Taylor length scales decreased, and positive stretch increased, increasing flame wrinkling and <em>u_t</em>. The <em>u_t</em> also increased as the temperature and <em>u’</em> increased. The fuel/air mixture with high laminar flame instability (<em>Le&lt;1</em>) has higher <em>u_t</em> than those with higher <em>Le</em>. However, the normalised <em>u_t</em> peaked in the region of high laminar burning velocity. This study concluded that the increase in <em>u_t</em> resulting from flame reactivity (laminar burning velocity) is more important than that from positive stretch (negative <em>Ma_b</em>) and flame instability.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113907"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large eddy simulations of turbulent premixed bluff body flames operated with ethanol, n-heptane, and jet fuels","authors":"Arvid Åkerblom,&nbsp;Christer Fureby","doi":"10.1016/j.combustflame.2024.113895","DOIUrl":"10.1016/j.combustflame.2024.113895","url":null,"abstract":"<div><div>Large Eddy Simulations (LES) are carried out targeting an unconfined premixed bluff body burner operated with ethanol, n-heptane, Jet A, and a Sustainable Aviation Fuel (SAF) labeled C1. The purpose is to validate the chosen simulation methodology for these fuels, which have not been simulated in the targeted case before, and to provide new information about how they burn and stabilize. The combustion of each fuel is modeled using Finite Rate Chemistry (FRC) and a pathway-centric chemical reaction mechanism. Subgrid-scale turbulence-chemistry interactions are modeled using a Partially Stirred Reactor (PaSR) approach. In accordance with previous experiments, snapshots of the OH and CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O distributions, as well as velocity, are extracted from the simulations and subjected to statistical analysis to obtain mean flame progress variable distributions, flame surface density, and CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O layer thickness. A mesh sensitivity analysis is carried out for all fuels, revealing that a crucial filter width threshold between 0.375 and 0.25 mm must be reached to achieve a stable flame and low mesh sensitivity. Statistically, the simulations show good agreement with previous experimental measurements. The flame sheet diameter is found to be approximately linearly correlated with extinction strain rate and Damköhler number, suggesting that resistance to turbulence is the determining factor for the flame size. The C1 flame is found to experience the weakest fluctuations, and a mechanism based on the relative time scales of flame propagation and the ignition of fuel decomposition products is proposed to explain this effect.</div><div><strong>Novelty and significance statement</strong></div><div>Sustainable aviation fuels are of major importance in reducing the climate impact of aviation, but their combustion is not nearly as well-understood as that of fossil jet fuels. Both experimental and numerical research is needed to map out the relationship between fuel composition and combustion performance, so that blending limits can be increased while guaranteeing safety, operability, and performance in aircraft engines. This work explores the turbulent flame dynamics of one commercial sustainable aviation fuel, C1. It is also the first numerical study to consider ethanol, n-heptane, Jet A, or C1 in the Cambridge bluff body burner, a case which has primarily been studied with methane. The results reveal several trends among the fuels which may be investigated further in future studies. C1 is found to be particularly resistant to outward fluctuations into the reactants, which connects fuel decomposition to flame stability.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113895"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stochastic fields with adaptive mesh refinement for high-speed turbulent combustion","authors":"Tin-Hang Un,&nbsp;Salvador Navarro-Martinez","doi":"10.1016/j.combustflame.2024.113897","DOIUrl":"10.1016/j.combustflame.2024.113897","url":null,"abstract":"<div><div>This paper presents a fully compressible joint velocity-species-energy probability density function (PDF) for modelling turbulent reactive flows across all Mach numbers. By incorporating velocities into the PDF, the approach unifies the treatment of non-linear source and turbulent transport terms with minimal model parameters. The PDF transport is solved using Eulerian stochastic fields, leveraging features from existing grid-based solvers like high-order shock-capturing schemes and adaptive mesh refinement. Validation test cases show that the solver achieves the theoretical convergence rate, maintains accuracy across refinement levels, and demonstrates convergence with a moderate number of fields. Additionally, it outperforms the Smagorinsky model by adding dissipation only when necessary. When applied to a supersonic jet flame, the solver reproduces experimental measurements and results from highly-resolved large eddy simulations, demonstrating robustness in supersonic reacting flows with dynamic flow fields and shocklet structures.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113897"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An experimental and modeling study of the auto-ignition of NH3/syngas mixtures in a shock tube","authors":"Shubao Song,&nbsp;Lin Zhang,&nbsp;Qifan Wang,&nbsp;Jiankun Shao","doi":"10.1016/j.combustflame.2024.113918","DOIUrl":"10.1016/j.combustflame.2024.113918","url":null,"abstract":"<div><div>Ammonia (NH₃) holds promise as an ideal zero-carbon fuel for modern energy systems. Co-combustion NH₃ with syngas can enhance the reactivity and improve the combustion efficiency of NH₃. In the current study, the auto-ignition and speciation experiments for NH₃/syngas mixtures were conducted at pressures of 0.86 and 4.0 atm, within a temperature range of 1234–1620 K, and across three equivalence ratios of 0.5, 1.0, and 2.0, with syngas content of 20 %, 30 % and 50 %, respectively. To the best of our knowledge, the experimental study for NH₃/syngas mixtures using shock tubes and laser absorption spectroscopy is the first in the literature. The experimental results show a similar reactivity under fuel-lean and stoichiometric conditions, which is slightly higher than the reactivity observed under fuel-rich conditions. The reactivity of the mixture is enhanced as the syngas content and pressure increase. The sensitivity analyses were conducted based on various kinetic models, and three key elementary reactions were identified that predominantly influence the oxidation of NH₃/syngas mixtures under experimental conditions: R1 (N₂H₂+M&lt;=&gt;NNH+H+M), R2 (NH₃+OH&lt;=&gt;NH₂+H₂O) and R3 (N₂H₂+H&lt;=&gt;NNH+H₂). The rate constants of these three crucial reactions were updated based on literature data, and an updated detailed kinetic model (NH₃-syngas model) was proposed based on our previous work (NH₃-C₂H₄ model). Simulated results by the NH₃-syngas model agree well with experimental data of the ignition delay times and time-histories of ammonia across different equivalence ratios, various syngas contents and pressures, as well as a series of literature data. Rate of production and sensitivity analyses were employed to elucidate the reaction pathways and crucial elementary reactions of NH₃/syngas mixtures. This investigation may contribute to optimizing kinetic models between ammonia and higher carbon number fuels in the future.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113918"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102714","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":"Flame kinetics at scramjet-engine-relevant conditions: Role of prompt dissociation of weakly-bound radicals","authors":"Amelia Kokernak ,&nbsp;Joel Mathew ,&nbsp;Raghu Sivaramakrishnan ,&nbsp;Stephen J. Klippenstein ,&nbsp;Jagannath Jayachandran","doi":"10.1016/j.combustflame.2024.113834","DOIUrl":"10.1016/j.combustflame.2024.113834","url":null,"abstract":"<div><div>Combustion in high-speed ram-based propulsion engines occurs under distinct thermodynamic conditions of high reactant temperatures (greater than 1000 K) and relatively low pressures (&lt;5 atm). There is a lack of fundamental flame measurements at such conditions that result in adiabatic flame temperatures (<em>T</em>_ad) exceeding 2500 K. In this work, we have measured laminar flame speeds of oxygen-enriched CH₄/oxidizer mixtures at sub-atmospheric conditions to probe kinetics at high <em>T</em>_ad using the isobaric spherically expanding flame approach. Simulations with recent kinetic models revealed increasing differences between data and model predictions with increasing <em>T</em>_ad, reaching up to 25 %. Kinetic analyses reveal that at the thermodynamic conditions in these O₂-enriched flames, i.e., lower pressures and higher <em>T</em>_ad, the effects of HCO prompt dissociation are accentuated. In addition to HCO, the prompt dissociations of CH₂OH and C₂H₅ are also considered. The prompt dissociations of all three radicals were evaluated and their effects considered in flame speed simulations. Reaction path analysis for the present flames revealed that approximately half of the reaction flux for HCO formation undergoes prompt dissociation to H + CO. Furthermore, these analyses also revealed that the pathways and sensitive reactions are similar between oxygen-enriched fuel/oxidizer mixtures and preheated fuel/air mixtures, if both have similar <em>T</em>_ad. Thus, flames of oxygen-enriched mixtures could be a surrogate to probe the flame chemistry of highly preheated mixtures at relatively low pressures that are often encountered in ram-based propulsion engine combustors.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113834"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103014","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":"An experimental and kinetic modeling study of the ignition of methane/n-decane blends","authors":"Jiaxin Liu ,&nbsp;Shangkun Zhou ,&nbsp;Pengzhi Wang ,&nbsp;Yuki Murakami ,&nbsp;Ahmed Abd El-Sabor Mohamed ,&nbsp;Mohsin Raza ,&nbsp;Adrian Nolte ,&nbsp;Karl Alexander Heufer ,&nbsp;Peter K. Senecal ,&nbsp;Henry J. Curran","doi":"10.1016/j.combustflame.2024.113884","DOIUrl":"10.1016/j.combustflame.2024.113884","url":null,"abstract":"<div><div>An experimental and kinetic modeling study of the combustion of methane/<em>n</em>-decane blends is performed. Ignition delay times (IDTs) of the pure fuels in addition to their blends are measured using both a shock tube and a rapid compression machine at three different methane/<em>n</em>-decane (mol%) compositions of 99/1 (M99D1), 95/5 (M95D5), and 80/20 (M80D20) in ‘air’, over the temperature range of 610–1495 K, at a pressure of 30 bar. A new chemical kinetic mechanism, GalwayMech1.0, is proposed to describe the combustion of these blends and is validated against the new IDT data including 1st-stage and total IDTs as well as existing experimental <em>n</em>-decane data available in the literature. Sensitivity analyses reveal that H-atom abstraction from <em>n</em>-decane by methyl peroxy radicals (CH₃Ȯ₂) play an important role in promoting blend reactivity at intermediate temperatures, which is not observed for pure <em>n</em>-decane. By investigating the effect of the <em>n</em>-decane concentration on the ignition characteristics, we found that the low ignition temperature limit is extended with increasing <em>n</em>-decane content with a non-linear reactivity-promoting effect. Flux analyses reveal that CH₄ oxidation in the blends is initiated via CH₄ + ȮH = ĊH₃ + H₂O, driven by the ȮH radicals produced from the early oxidation of <em>n</em>-decane and the CH₃Ȯ₂ radicals formed from CH₄ oxidation which subsequently accelerates <em>n</em>C₁₀H₂₂ consumption via H-atom abstraction. Comparisons of CH₄/<em>n</em>C₁₀H₂₂ and H₂/<em>n</em>C₁₀H₂₂ blends from a previous study demonstrate consistently higher reactivity for hydrogen blending compared to methane and that the magnitude of this increase diminishes with increasing <em>n</em>-decane content. Finally, we also compare our current model predictions of our new data with other <em>n</em>-decane models available in the literature.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113884"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103018","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}