Combustion and Flame最新文献

{"title":"Experimental and fuel-surrogates modeling study of the oxidation of specialty cetane number fuels","authors":"Mohammed Abdulrahman ,&nbsp;Subharaj Hossain ,&nbsp;P.T. Lynch ,&nbsp;Eric K. Mayhew ,&nbsp;K. Brezinsky","doi":"10.1016/j.combustflame.2024.113910","DOIUrl":"10.1016/j.combustflame.2024.113910","url":null,"abstract":"<div><div>Single pulse shock tube experiments were performed at 50 atm nominal pressure and 4 milliseconds nominal reaction time over a temperature range of 900–1800 K, to study the oxidation speciation of a multicomponent jet fuel, F-24, and six cetane number (CN) specialty fuels - CN30, CN35, CN40, CN45, CN50, and CN55. The oxidation experiments were carried out at an equivalence ratio of approximately 1.0. Gas chromatography (GC) was used to quantitatively and qualitatively analyze the post shock gases. The correlation between the formation of critical oxidation species and the chemically controlled combustion propensity as reflected by the cetane number of each fuel was investigated. The species were simulated using a surrogate-based mechanism from the CRECK Modelling Group. The species produced from the oxidation of the CN fuels were initially modeled using optimized chemical composition surrogates, but with less than satisfactory agreement. Efforts to enhance the agreement of experiment with model results by increasing the iso-paraffinic content in the surrogates did not yield significant improvements. Subsequently, the aromatic content of the surrogates was adjusted, resulting in surrogates whose model predicted oxidation species better matched the experimental data. Rate of production, sensitivity and reaction path analyses using the surrogate model were performed to obtain the important reactions responsible for the formation of key species and to examine the chemistry of complex multicomponent fuel systems. The primary reactions responsible for driving the oxidation chemistry were largely influenced by the chemical functional groups present in the fuels. In addition, the study highlights the effectiveness of the fuel-surrogate approach where surrogates representing the chemical functional group composition of the parent fuel serve as a valuable tool for predicting the combustion chemistry of unknown fuels.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113910"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103022","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":"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 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}

{"title":"A global evolution of the downward jet flame behavior: From the laminar to the turbulent","authors":"Xiepeng Sun,&nbsp;Jiang Lv,&nbsp;Yu Han,&nbsp;Xiaolei Zhang,&nbsp;Fei Tang,&nbsp;Longhua Hu","doi":"10.1016/j.combustflame.2024.113906","DOIUrl":"10.1016/j.combustflame.2024.113906","url":null,"abstract":"<div><div>The diffusion jet flame is a high-speed flow gas ignited at the outlet, a common combustion behavior in fundamental science of combustion, including applications in the industrial exhaust gas treatment torches and engines. This paper investigates experimentally the downward jet flame characteristics from the laminar to the turbulent, which has not been reported comprehensively yet. The overall jet flame length, jet flame downward distance, temperature and flame radiation heat flux profile are studied, as important characteristic parameters determining the flame boundary in vertical direction, the farthest distance that the flame could travel, as well as the thermal effect on the surrounding, respectively. Experiments were conducted to explore the global evolutionary process of downward jet flame with increasing initial fuel jet velocity for various circle nozzle diameters (3 mm, 4 mm and 5 mm), fuel types (pure fuel and blended fuel), and Reynolds numbers widely ranging from 65 to 97,209 involving laminar, transition and turbulent combustion regimes before reaching the flame blowout limit. The downward jet flame length and the downward distance show a non-monotonic evolution with the Reynolds number or heat release rate, <em>i.e.</em>, first increase at the laminar combustion regime, change a little at the transition regime, and finally increase significantly after reaching fully turbulent combustion regime. The vertical temperature profile along the centerline of the downward jet flame is associated with the downward jet flame morphologic characteristic parameters, it decreases significantly with the non-dimensional height at the intermittent region compared to the upward jet flame. The flame radiation fraction of the downward jet flame based on the measured flame radiation heat fluxes first changes a little and then decreases with the Reynolds number as a power function. The flame length could be well correlated by the non-dimensional heat release rate, the flame Froude number as well as the non-dimensional volumetric flow rate based on the air entrainment dynamics. The jet flame downward distance could be well correlated by the momentum-buoyancy length scale at the turbulent combustion regime. A non-dimensional global model involving the momentum-buoyancy length, flow rate length scale and the stoichiometric air-fuel ratio is developed to describe the global jet flame downward distance evolution. This work provides essential and fundamental knowledge about the dynamic evolution of downward jet flame in designing rocket propulsion/combustor structures, combustion and evolution characteristics.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113906"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103024","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":"The influence of spatial dispersion on the steady-state characteristics and thermodynamic instability fluctuations of one-dimensional iron particle flames","authors":"Chengcheng Shan ,&nbsp;Haogang Wei ,&nbsp;Jiefeng Wan ,&nbsp;Zijian Zhang ,&nbsp;Philip De Goey ,&nbsp;Lei Zhou","doi":"10.1016/j.combustflame.2024.113889","DOIUrl":"10.1016/j.combustflame.2024.113889","url":null,"abstract":"<div><div>This study utilizes a simplified one-dimensional discrete model to analyze the characteristic parameters involved in the flame propagation of iron particles. It focuses on the influence of dispersive \"micro flames\" within these flames on propagation dynamics, investigating stable and unstable scenarios. The model adopts the form of particle suspension delineating alternant reaction intervals and inert intervals. The spatial dispersion rate (Γ) which describes the spatial extent of the \"micro flames\" is introduced, with Γ = 1 for the continuum model and Γ &gt; 1 for the discrete model. Theoretical equations, combining kinetic and diffusion equations, are solved with the finite difference method. The solution is evaluated preliminarily to distinguish numerical instability and thermodynamic instability. Additionally, in the preset time and space range, conditions for different equivalence ratios, particle radius and spatial dispersion rates are analyzed emphatically, with a comparison of typical simulation results and experimental data. As shown in the numerical simulation, the flame maintains stable propagation when <em>ϕ</em>≥0.7. The flame front, where the particle temperature rises above the gas temperature, extends backward with the increase of particle radius. The increase of Γ tends to extend the flame front of the fuel-lean flame and constringe that of the fuel-rich flame. Thermodynamic instability occurs in fuel-lean suspension with its manifestation preliminarily classified to distinct fluctuation, faint fluctuation and the final cessation. The increase of Γ also extends the flame propagation time under the dominance of thermodynamic instability, indicating different temperature structure evolution from the continuum model.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113889"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102426","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":"Machine learned compact kinetic model for liquid fuel combustion","authors":"Mark Kelly ,&nbsp;G. Bourque ,&nbsp;M. Hase ,&nbsp;S. Dooley","doi":"10.1016/j.combustflame.2024.113876","DOIUrl":"10.1016/j.combustflame.2024.113876","url":null,"abstract":"<div><div>A novel data-intensive methodology to produce a high fidelity, extremely-reduced “compact” kinetic model for a high boiling point complex liquid fuel is proposed and demonstrated. A five-component surrogate definition for the liquid fuel is developed that displays a high accuracy to the experimentally-derived combustion property targets. The calculations of the Lawrence Livermore National Lab diesel surrogate model containing 6476 species are used to serve as gas turbine industry-defined performance targets for this surrogate.</div><div>Acknowledging that the retention of a multi-component surrogate definition is a limitation on the size of the model, the surrogate fuel is consolidated into a single virtual molecule. Subsequently, the reaction mechanism is simplified by replacing high carbon number chemistry with a virtual scheme. This scheme links the virtual fuel molecule to low carbon number chemistry using four virtual species and forty-four virtual reactions, resulting in a reduction to 429 species in the model.</div><div>The Machine Learned Optimisation of Chemical Kinetics (MLOCK) algorithm is adapted to “compact” this model. Compaction is the over-reduction and optimisation of a kinetic model. Path flux analysis generates an overly-reduced model with 31 species that has a poor replication of the detailed model calculations. To address this, virtual reaction rate constants of important virtual reactions are numerically optimized to detailed model high temperature calculations. MLOCK systematically perturbs all three virtual Arrhenius reaction rate constant parameters to generate and evaluate numerous model candidates, refining the search space based on prior results, finding better models. A low temperature virtual reaction network, comprising one new virtual species and three new virtual reactions, is appended to the high temperature compact model. MLOCK is employed to reoptimize the model to calculations at low and intermediate temperatures.</div><div>The application of this methodology results in a 32-species compact model in ChemKin/Cantera format, which retains fidelities in the range of 76 to 92 % across a comprehensive range of gas-turbine relevant performance calculations for low, intermediate and high temperatures.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"272 ","pages":"Article 113876"},"PeriodicalIF":5.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102427","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}