Combustion and Flame最新文献

{"title":"Numerical and experimental study of stability limits of methane-air flame stabilized on a flat porous burner at normal and elevated pressure","authors":"Anastasia Moroshkina ,&nbsp;Sofia Babina ,&nbsp;Alina Ponomareva ,&nbsp;Evgeniy Sereshchenko ,&nbsp;Vladimir Mislavskii ,&nbsp;Vladimir Gubernov ,&nbsp;Viatcheslav Bykov","doi":"10.1016/j.combustflame.2025.114336","DOIUrl":"10.1016/j.combustflame.2025.114336","url":null,"abstract":"<div><div>The limits of existence of a steady planar methane-air flame stabilized on a flat porous burner at normal and elevated pressure (2, 4 and 6 bar) have been experimentally and numerically investigated. In particular, the critical conditions for the blow-off and diffusive-thermal oscillations have been determined in the plane of parameters: mass flow rate vs. equivalence ratio. The Hopf frequency of oscillations is measured at the diffusive-thermal oscillation boundary. The results of numerical simulations, undertaken with the use of detailed reaction mechanisms, such as GRI, FFCM, USC II, SanDiego, and Aramco, show that, despite the good qualitative agreement with the experimental data, the relative quantitative difference between the numerical simulations and the experimental measurements is quite large. It is of the order of several tens of percent and is especially evident when the measurements are performed away from stoichiometry and under high pressures. In order to verify and validate detailed reaction mechanisms, in addition to the standard tests such as measurement of laminar burning velocity, ignition delay time and extinction strain rate, it is necessary to obtain a wider range of experimental data. It is especially important at elevated pressures and high temperatures. Determining the characteristics of the diffusion-thermal oscillations is a suitable way to achieve this.</div><div><strong>Novelty and Significance Statement</strong></div><div>For the first time, we experimentally found the critical conditions for the blow-off and onset of diffusive thermal pulsating instabilities, as well as the characteristics of diffusive thermal oscillations for the burner stabilized methane-air flames at elevated pressure. These data were compared for the first time with the predictions of several detailed reaction mechanisms to verify their performance under such conditions. The novel findings reported in this work on the regions of existence of stable combustion regimes are significant for the design of practical burners, while the data on the conditions and characteristics of the critical phenomena will facilitate the development of accurate and efficient mechanism of methane combustion.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114336"},"PeriodicalIF":5.8,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144662772","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":"Effects and kinetic mechanisms of suppression gases on H2/air mixture explosions: A comparative study","authors":"Chunlian Cheng ,&nbsp;Rongjun Si ,&nbsp;Lei Wang ,&nbsp;Zichao Huang ,&nbsp;Quansheng Jia ,&nbsp;Hao Zhang ,&nbsp;Mengying Zhang ,&nbsp;Baisheng Nie","doi":"10.1016/j.combustflame.2025.114354","DOIUrl":"10.1016/j.combustflame.2025.114354","url":null,"abstract":"<div><div>This study systematically investigated the effects of various inhibitors (N₂, CO₂, Ar, and C₃HF₇) and two composite inhibitors on hydrogen explosions at identical equivalence ratios to elucidate their suppression mechanisms. Numerical simulations revealed the kinetic characteristics of hydrogen explosion processes under inhibitor effects. The results demonstrate that explosion intensity progressively decreases with increasing inhibitor concentration. While N₂, CO₂, and Ar suppress explosions through both dilution and endothermic effects, CO₂ additionally exhibits chemical inhibition via radical consumption. At low concentrations, CO₂ shows weaker suppression than N₂ and Ar due to limited chemical inhibition, but its effectiveness significantly improves at higher concentrations. Although low-concentration C₃HF₇ promotes explosion pressure through thermal effects, higher concentrations enable comparable suppression efficiency as its pyrolyzed fluorinated products consume critical radicals (H·, O·, and OH·). The C₃HF₇_<img>CO₂ composite system effectively counteracts the pressure-enhancing effect of low-concentration C₃HF₇. Through synergistic physical and chemical inhibition, it suppresses key radical generation, reduces radical concentration and heat release rate, while enhancing OH radical and temperature sensitivity, thereby achieving efficient explosion suppression at low inhibitor concentrations. These findings provide theoretical support for hydrogen energy safety, risk management, and the development of composite suppressants.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114354"},"PeriodicalIF":5.8,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144666030","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":"Automatic generation of compact kinetic models for large alkane oxidation","authors":"Sirio Brunialti ,&nbsp;Xiaoyuan Zhang ,&nbsp;Qi Wang ,&nbsp;Tiziano Faravelli ,&nbsp;S. Mani Sarathy","doi":"10.1016/j.combustflame.2025.114355","DOIUrl":"10.1016/j.combustflame.2025.114355","url":null,"abstract":"<div><div>Large alkanes are principal chemical components in many petroleum and alternative renewable fuels. The development of oxidation models for large alkanes is often complex and time-consuming. A methodology for the automatic generation of detailed and lumped kinetic models of oxidation of large alkanes is presented herein. This procedure is built upon the authors’ previous work (Brunialti et al., 2023), wherein an automatic procedure for generating oxidation models of alkanes based on MAMOX++ software was developed. The procedure is based on a rate rule approach, and it can generate detailed and lumped reaction mechanisms. A new set of rate rules was developed to better describe the reactivity of large alkanes at high and low temperatures. The procedure also includes automatic thermochemical-property computation. The reaction mechanism generation procedure was reviewed to minimize the reaction mechanism size and required user inputs. Detailed reaction mechanism and lumped reaction mechanisms were generated for 40 alkanes with a carbon number of 5–16. The model predictions were compared with experimental data obtained from jet-stirred reactors, shock tubes, rapid compression machines, and laminar burning velocities. Validations were performed for 30 alkanes under a broad range of temperatures, pressures, and equivalence ratios. The predicted and measured values exhibited good agreement under all conditions for all fuels except for large, highly branched alkanes. The lumped models can reproduce the predictions of the detailed models with high fidelity under all explored conditions while considerably reducing the number of species and reactions involved in the reaction mechanism. Software capabilities for modeling the reactivity of extremely large alkanes were assessed in a comparative study for linear alkanes with up to 30 carbon atoms. Detailed and lumped models for gasoline primary reference fuel mixtures were generated and validated to demonstrate the procedure capabilities for generating compact, task-tailored models.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114355"},"PeriodicalIF":5.8,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144666029","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 innovative activity-oriented direct reaction screening method for reduction of detailed chemical kinetic mechanism","authors":"Wei Li ,&nbsp;Ziying Zhang ,&nbsp;Tiemin Xuan ,&nbsp;Zhixia He ,&nbsp;Qian Wang","doi":"10.1016/j.combustflame.2025.114347","DOIUrl":"10.1016/j.combustflame.2025.114347","url":null,"abstract":"<div><div>An activity-oriented direct reaction screening (AODRS) method is proposed to simplify the reduction of detailed chemical kinetic mechanism. This method requires only four parameters (c_GISS, c_LO, c_T, and c_RIT) to generate a skeletal mechanism. Extensive experience or expertise is not necessary for identifying important species, as these species are determined locally and dynamically based on their absolute molar converting fluxes. c_GISS is used to dynamically identify and construct the global important species scope, while c_LO is used to dynamically identify the local target species. Reactions with higher contribution coefficients than c_T and having species all belonging to the global important species scope are classified as locally important. Then locally important reactions with higher importance tendency than c_RIT are identified as global important reactions. To validate the proposed method, detailed mechanisms for NH_3<img>CH₄ and n-heptane are reduced stepwise. As c_GISS and c_LO increase while c_T and c_RIT decrease, the relative errors in ignition delay time, laminar flame speed, and species concentrations generally decrease. With the criterion of 5 % maximum relative error in ignition delay time, a skeletal mechanism achieving reductions of 62 % in reactions and 59 % in species is obtained for the NH_3<img>CH₄. Meanwhile, a skeletal mechanism for n-heptane within 10 % relative error in ignition delay time achieves reductions of 67 % in reactions and 58 % in species. Additionally, ignition delay time, laminar flame speed, and species concentrations are extensively evaluated. Results indicate that, with a comparable number of reactions, skeletal mechanisms generated by AODRS exhibit better agreement with detailed mechanisms compared to skeletal mechanisms generated by DRGEPSA and DRGEP methods. Finally, the recommended value ranges for c_GISS, c_LO, c_T, and c_RIT have been further constrained.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114347"},"PeriodicalIF":5.8,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656961","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":"1,3,5-trimethylcyclohexane pyrolysis at high pressure and temperature: Insights from theory, experiment and simulation","authors":"Subharaj Hossain ,&nbsp;Moirangthem Kiran Singh ,&nbsp;Jagadeesh Gopalan ,&nbsp;Elangannan Arunan","doi":"10.1016/j.combustflame.2025.114345","DOIUrl":"10.1016/j.combustflame.2025.114345","url":null,"abstract":"<div><div>The pyrolysis of 1,3,5-trimethylcyclohexane (T135CH), which is a proposed surrogate for RP-3, has been investigated at a temperature range of 1017 - 1542 K and a pressure range of 13.4 – 23.5 bar. Mole fraction profiles of 30 pyrolysis products were obtained using GC-FID. Methane was found to be the most abundant product at high temperatures, followed by acetylene, while benzene was the most abundant aromatic product. A detailed kinetic model comprising 302 species and 967 reactions was developed, which showed reasonable agreement with the experimental data. This was aided by detailed ab initio calculations of elementary reactions at the CBS-QB3, CASSCF/MRCI levels of theory and conventional transition state theory (TST/VTST) calculations of rate parameters. The rate of production (ROP) analysis revealed that both unimolecular decomposition of T135CH (via CH₃ elimination) and H-abstraction reactions of T135CH are responsible for its consumption. Sensitivity analysis demonstrated that the CH₃ elimination channel is the most sensitive reaction for T135CH consumption. Additionally, sensitivity analysis of aromatic product formation revealed that allene (aC₃H₄) and dimethylcyclohexanyl radical (S1X35DCH) play a critical role in the formation of aromatic products. The overall rate constant for T135CH decomposition was found to be:</div><div><span><math><mrow><mi>k</mi><mo>/</mo><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>=</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>6.32</mn><mo>±</mo><mn>0.23</mn></mrow></msup><mi>e</mi><mi>x</mi><msup><mrow><mi>p</mi></mrow><mfrac><mrow><mo>(</mo><mrow><mo>−</mo><mn>25.1</mn><mo>±</mo><mn>1.3</mn><mo>/</mo><mi>k</mi><mi>c</mi><mi>a</mi><mi>l</mi><mo>.</mo><mi>m</mi><mi>o</mi><msup><mrow><mi>l</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow><mo>)</mo></mrow><mrow><mspace></mspace><mi>R</mi><mi>T</mi></mrow></mfrac></msup></mrow></math></span></div><div>These findings will advance our comprehension of the unimolecular decomposition of T135CH, as well as the reaction pathways involved in the formation of its aromatic products. Ultimately, this knowledge will help us better understand the combustion process of transportation fuels.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114345"},"PeriodicalIF":5.8,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656962","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 combustion chemistry of China aviation kerosene (RP-3) through the HyChem approach","authors":"Yecheng Song ,&nbsp;Wei Shen ,&nbsp;Shijie Bai ,&nbsp;Shilong Li ,&nbsp;Xingyu Liang ,&nbsp;Jiankun Shao ,&nbsp;Zechang Liu ,&nbsp;Guangyuan Feng ,&nbsp;Chengyuan Zhao ,&nbsp;Xu He ,&nbsp;Yang Li ,&nbsp;Jinhu Liang ,&nbsp;Xuefeng Guan ,&nbsp;Tianhan Zhang ,&nbsp;Zhiwei Wang ,&nbsp;Zhi-Qin John Xu ,&nbsp;Dongping Chen ,&nbsp;Kun Wang","doi":"10.1016/j.combustflame.2025.114339","DOIUrl":"10.1016/j.combustflame.2025.114339","url":null,"abstract":"<div><div>To address the complexity of modeling combustion chemistry of real multi-component fuels, the Hybrid Chemistry (HyChem) approach has been developed and tested for some typical jet fuels such as Jet A, JP-8, JP-10, etc. Still, the development and evolution of HyChem remain ongoing, and its potential has yet to be fully explored. The primary objective of the present study is to develop a HyChem model for describing the combustion chemistry of RP-3 while demonstrating the evolutionary understanding of the HyChem approach. In addition to the comprehensive new datasets provided by the present study as well as the development, validation, and reduction of an RP-3 HyChem model, several innovations were made regarding the HyChem development. Firstly, pyrolysis and oxidation experiments were performed in a flow reactor and utilized, sequentially, to constrain the coefficient parameters of the lumped reactions of the fuel decomposition submodel of HyChem. Meanwhile, ignition delay time and laminar flame speed measurement experiments were conducted in a shock tube and a constant-volume combustion bomb respectively, to obtain new datasets. Secondly, the species 1,3-butadiene was characterized as an additional critical intermediate during the RP-3 decomposition, in addition to these identified during the Jet A decompositions, and the RP-3 HyChem model was thus proposed to be revised to contain 1,3-butadiene. Thirdly, the present study demonstrated that by taking advantage of a flow reactor system equipped with GC/microGC or GC-MS that was able to characterize a complete kinetic picture of intermediate species distribution at the millisecond reaction time scale, a reliable HyChem model could be effectively constructed. Lastly, a newly developed machine-learning-based approach DeePMR, through iterative sampling, perturbation, and deep neural network (DNN)-guided screening, was shown to effectively achieve compact reduced models with state-of-the-art accuracy. In summary, the present study revealed substantial evolutionary understanding of the HyChem approach, which would greatly improve accessibility for researchers through the selection and application of different experimental apparatus and diagnostics to explore the HyChem approach and to develop proper HyChem models, for evaluating next-generation fuels and engine applications.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114339"},"PeriodicalIF":5.8,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656963","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":"Simulations of hydrogen-air detonations using Direct Simulation Monte Carlo","authors":"Shrey Trivedi ,&nbsp;Jorge S. Salinas ,&nbsp;John K. Harvey ,&nbsp;Alexei Y. Poludnenko ,&nbsp;Jacqueline H. Chen","doi":"10.1016/j.combustflame.2025.114333","DOIUrl":"10.1016/j.combustflame.2025.114333","url":null,"abstract":"<div><div>In this paper, the Direct Simulation Monte Carlo (DSMC) method is used to perform molecular level simulations of one-dimensional (1-D) hydrogen-air detonations. Since DSMC emulates the motion of real molecules, it is well suited for rarefied flow problems and is capable of treating rigorously processes in which measurable departures from molecular and chemical equilibrium exist, such as for molecular transport, internal energy relaxation, and chemical reactions. DSMC has been demonstrated to be a robust and more appropriate tool for fundamental studies of reacting flows at higher densities where regions of thermal and chemical non-equilibrium exist. Two cases of stoichiometric hydrogen-air mixtures are considered. First, a preheated case is simulated with reactants at an initial temperature of 900 K and an initial pressure of 0.3 atm. The second example is a detonation wave at a standard initial condition of 300 K and 1 atm. The results are compared with the Zel’dovich–von Neumann–Döring (ZND) solution obtained using the Shock and Detonation (SDT) toolbox. The temperature, pressure, flow velocity, density and species mass fractions are compared. It is found that for the preheated case, using DSMC results in a robust and steady detonation structure and shows excellent agreement with the ZND solution. The second example of the detonation wave at standard conditions is expected to fluctuate, and DSMC captures this effectively. However, the 1-D profiles differ slightly from the ZND solution. DSMC shows strong promise to carry out molecular-level simulations of detonations but requires ab initio data for robust non-equilibrium reacting flow simulations.</div><div><strong>Novelty and significance statement</strong></div><div>Combustion studies using the Direct Simulation Monte Carlo (DSMC) method have been few and far between. Although it is usually thought of as a method for computing rarefied flows, it is well-suited for flows with thermal and chemical non-equilibrium since it can incorporate information directly from <em>ab-initio</em> calculations, which can be used to estimate reaction rates for challenging elementary reactions. Such conditions can be encountered in scramjets and rotating detonation engines. The novelty of this paper lies in assessing the ability of DSMC to simulate hydrogen-air detonation for which aspects of molecular non-equilibrium may be present. This is a proof-of-principle study utilizing the current models, with the aim of extending this approach to other combustion problems with higher levels of non-equilibrium. This will particularly require improvements in reaction rate modeling in DSMC.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114333"},"PeriodicalIF":5.8,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656314","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":"Theory and analysis of module-scale thermal runaway propagation","authors":"Danyal Mohaddes,&nbsp;Yi Wang","doi":"10.1016/j.combustflame.2025.114327","DOIUrl":"10.1016/j.combustflame.2025.114327","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Lithium-ion batteries (LIBs) are ubiquitous in consumer and industrial applications due to their high energy density and cycle life. Under nominal use conditions, they provide a safe means of energy storage. If abused, they can undergo thermal runaway (TR), i.e., rapid localized heating that propagates as a thermo-chemically reacting front, generating combustible gas, increasing internal pressure, leading to venting. Battery Energy Storage Systems (BESS) are collections of LIBs which stabilize power grids with a high penetration of variable and intermittent power sources. If one LIB in the BESS undergoes TR, the immediately neighboring LIBs will be abused thermally and may undergo TR, resulting in a cascade of cell-to-cell failures known as thermal runaway propagation (TRP). Matters are further complicated by the potential for external flame heating or explosion if the vented gases mix with ambient air and ignite.&lt;/div&gt;&lt;div&gt;We examine TRP across a LIB stack parametrically in a non-dimensional setting. Pouch-format LIBs are considered since these are used in some BESS applications and permit a quasi-one-dimensional unsteady analysis. From the governing equations, key non-dimensional groups controlling the solution behavior are identified. The mean consumption rate is identified as a scalar value mapping the non-dimensional groups to a hazard metric for a LIB stack. Solution of the system is carried out numerically and the parametric dependencies of the hazard metric on the non-dimensional groups are demonstrated. We identify a regime in the parameter space where TRP is inhibited, constituting a passively safe design space for LIB stacks. Another regime is identified in which flame heating results in bi-directional TRP, doubling the mean consumption rate and exacerbating the hazard. This work provides designers, engineers and scientists with a formalized, non-dimensional framework and compact parameter set to gain an intuitive understanding of, qualitatively compare, and potentially ameliorate the TR hazards posed by different LIB stacks.&lt;/div&gt;&lt;div&gt;&lt;strong&gt;Novelty and significance&lt;/strong&gt;&lt;/div&gt;&lt;div&gt;Thermal runaway is the principal failure mode for large-scale battery energy storage systems used increasingly worldwide for power grid stabilization. A formalized framework with a compact non-dimensional parameter set is needed to effectively assess and ameliorate hazards posed by different lithium-ion battery modules. The main novelty of this work is that it formulates, solves and analyzes for the first time the problem of thermal runaway initiation and propagation in a module of multiple lithium-ion battery cells in an unsteady, non-dimensional setting suitable for detailed physical analysis. This framework allows the derivation of a hazard metric, from which non-dimensional parameter regimes of passive safety due to non-propagation, and exacerbated hazard from bi-directional propagation, are identified and their physical mechanisms elucida","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114327"},"PeriodicalIF":5.8,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144634146","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 data-driven sparse learning approach to reduce chemical reaction mechanisms","authors":"Shen Fang ,&nbsp;Siyi Zhang ,&nbsp;Zeyu Li ,&nbsp;Wang Han ,&nbsp;Qingfei Fu ,&nbsp;Chong-Wen Zhou ,&nbsp;Lijun Yang","doi":"10.1016/j.combustflame.2025.114337","DOIUrl":"10.1016/j.combustflame.2025.114337","url":null,"abstract":"<div><div>Reducing detailed chemical reaction mechanisms is a crucial strategy for mitigating the computational cost of reacting flow simulations. In this work, we propose a novel sparse learning (SL) approach that leverages reaction sparsity to systematically identify influential reactions for mechanism reduction. Specifically, the SL method learns an optimized weight vector to rank reaction importance, enabling the construction of compact reduced mechanisms by retaining species involved in the most influential reactions. The approach is extensively validated against fundamental combustion properties and turbulence-chemistry interactions across various hydrocarbon fuel/air systems. The results demonstrate that the SL-based reduced mechanisms accurately predict ignition delay times, laminar flame speeds, species mole fractions, and turbulence-chemistry interactions over a broad range of operating conditions. Furthermore, comparative analysis with existing reduction methods shows that the SL method yields more compact mechanisms while maintaining similar accuracy levels, particularly for large-scale mechanisms with extensive species and reactions. These findings highlight the potential of SL as an effective tool for developing reduced chemical mechanisms with improved efficiency and scalability.</div><div><strong>Novelty and Significance Statement</strong></div><div>The novelty of this work lies in the development of a sparse learning (SL) approach for chemical mechanism reduction, which systematically explores reaction sparsity by identifying influential reactions through statistically learned weight criteria. This method enables the construction of highly compact reduced mechanisms while preserving predictive accuracy. Comparative assessments demonstrate that SL outperforms existing reduction techniques, such as DRGEP and DRGEPSA, by yielding mechanisms with fewer species under the same error constraints. Moreover, SL achieves more extensive reductions than state-of-the-art methods while maintaining comparable maximum relative errors. This work introduces a novel data-driven strategy for efficient mechanism reduction, offering significant potential for advancing computational combustion modeling.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114337"},"PeriodicalIF":5.8,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144634145","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 absorption spectroscopy measurements of temperature and CO profiles in opposed-flow diffusion flames of HTPB","authors":"Austin McDonald ,&nbsp;Jonathan J. Gilvey ,&nbsp;Michael J. McQuaid ,&nbsp;Chiung-Chiu Chen ,&nbsp;Jeffrey D. Veals ,&nbsp;Christopher P. Stone ,&nbsp;Steven F. Son ,&nbsp;Christopher S. Goldenstein","doi":"10.1016/j.combustflame.2025.114325","DOIUrl":"10.1016/j.combustflame.2025.114325","url":null,"abstract":"<div><div>This work presents scanned-wavelength direct-absorption measurements of temperature and CO mole fraction in opposed-flow diffusion flames of hydroxyl-terminated polybutadiene (HTPB). HTPB strands were held in an opposed-flow burner under an opposed flow of O<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> or 50/50 O<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>/N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> to create quasi-steady and quasi-1D diffusion flames above the fuel strand. The opposed-flow burner was translated vertically to effectively scan the measurement line-of-sight vertically through the flame. A quantum-cascade laser (QCL) was scanned across the P(2,20), P(0,31), and P(3,14) absorption transitions in CO’s fundamental vibration bands near 2008 cm⁻¹ at 10 kHz to determine the temperature and CO mole fraction. The laser beam was passed through sapphire rods held close to the flame edge to bypass the flame boundary and provide a well defined path length for mole fraction measurements. The measured profiles and fuel regression rates were compared to predictions produced by a steady opposed-flow 1D diffusion flame model. The model utilized chemical kinetics mechanisms employing two different assumptions for the nascent gaseous product of HTPB pyrolysis: <span><math><mrow><msub><mrow><mi>C</mi></mrow><mrow><mn>4</mn></mrow></msub><msub><mrow><mi>H</mi></mrow><mrow><mn>6</mn></mrow></msub></mrow></math></span> or <span><math><mrow><msub><mrow><mi>C</mi></mrow><mrow><mn>20</mn></mrow></msub><msub><mrow><mi>H</mi></mrow><mrow><mn>32</mn></mrow></msub></mrow></math></span>. It was found that the latter model produced temperature and CO profiles along with regression rates that agreed more closely with the measured temperatures, CO mole fraction, and fuel regression rates.</div><div>Novelty and Significance Statement</div><div>A novel experimental setup that enables high-fidelity laser-absorption measurements of 1D profiles of temperature and species in opposed-flow diffusion flames of solid fuels is described. Further, this work presents the first high resolution (sub-millimeter) spatially resolved measurements of temperature and CO mole fraction in opposed-flow diffusion flames of hydroxyl-terminated polybutadiene (HTPB). The measurements are compared to theoretical predictions and this proved that a new chemical kinetic mechanism for HTPB pyrolysis and combustion enables significantly more accurate predictions of temperature and CO profiles as well as fuel regression rates.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114325"},"PeriodicalIF":5.8,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144631305","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}