Proceedings of the Combustion Institute最新文献

{"title":"Modeling dense droplet spray combustion with multiple-mapping conditioning","authors":"Jan Wilhelm Gärtner,&nbsp;Ka Ho Lam,&nbsp;Andreas Kronenburg","doi":"10.1016/j.proci.2025.105895","DOIUrl":"10.1016/j.proci.2025.105895","url":null,"abstract":"<div><div>Accurate modeling of dense spray combustion remains a key challenge due to complex two-phase interactions, turbulence, and evaporation dynamics. This study advances the sparse stochastic particle method MMC-LES by introducing a novel droplet–droplet–particle (DDP) coupling model to improve the representation of phase interactions in dense droplet-laden flows. The performance of this approach is assessed against Carrier Phase Direct Numerical Simulations (CP-DNS) for a double shear layer configuration, extending previous work on sparse-Lagrangian methods. While the nearest-neighbor (NNB) coupling strategy accurately predicts global scalar statistics for dilute sprays, it overestimates evaporation rates in dense conditions due to inadequate representation of local fuel mass fraction variations. Conditioning the nearest neighbor selection on the mixture fraction or using double conditioning on both mixture fraction and temperature does not lead to improved results due to the lack of a model for inter-droplet interactions. The newly proposed DDP model mitigates these issues by incorporating inter-droplet effects, leading to improved agreement with CP-DNS results.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105895"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262551","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":"Stabilised combustion of lean hydrogen–air mixtures in the presence of silica","authors":"Aki Fujinawa,&nbsp;Ewa J. Marek","doi":"10.1016/j.proci.2025.105841","DOIUrl":"10.1016/j.proci.2025.105841","url":null,"abstract":"<div><div>The urgent need to transition out of our reliance on fossil fuels motivates the development of emission-free combustion technologies. Here we demonstrate a method to burn hydrogen, a fuel that can be produced with green electricity, in a packed bed of silica particles. The presence of silica particles prevents the significant increase in process temperature encountered in gas-flame arrangements, thereby enabling the conversion of hydrogen to heat while mitigating nitrogen oxide emissions. Partial combustion is observed in packed beds of silica particles below the gas-phase ignition temperature, suggesting that a heterogeneous combustion mechanism dominates at low temperatures. Above the gas-phase ignition temperature, silica particles prevent thermal runaway by acting as a heat sink, suppressing the OH<span><math><mo>•</mo></math></span> radical-producing chain branching reactions, and instead promoting the conversion of hydrogen to water vapour by a mechanism involving the hydroperoxyl intermediate. Radical quenching and recombination reactions on surfaces of silica particles further reduce the availability of free radicals during in-bed combustion. The combustion of hydrogen with solid particles of silica can easily be scaled up using a fluidised configuration, owing to the low cost and wide availability of quartz sand. We present a unique opportunity for the stabilised, nitrogen oxides-free conversion of hydrogen to heat, offering an economical and scalable solution for large-scale industrial heat production with important economic and environmental value.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105841"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation and optimization of ammonia–hydrogen chemical kinetics with ignition delay times from shock tubes","authors":"Torsten Methling ,&nbsp;Michael Pierro ,&nbsp;Nikolas Hulliger ,&nbsp;Justin J. Urso ,&nbsp;Jakob Krämer ,&nbsp;Clemens Naumann ,&nbsp;Markus Köhler ,&nbsp;Subith S. Vasu","doi":"10.1016/j.proci.2025.105835","DOIUrl":"10.1016/j.proci.2025.105835","url":null,"abstract":"<div><div>A combined experimental and numerical approach investigates the ignition delay times of ammonia–hydrogen mixtures in oxygen or synthetic air measured in shock tubes under different dilutions with argon and nitrogen. A series of novel ignition delay time measurements is presented for stoichiometric fuel–air mixtures diluted 1:10 and 1:5 in argon as well as 1:2 in nitrogen at the shock tube facility of the German Aerospace Center (DLR). The initialized gas conditions behind the reflected shock waves range between 940–2200 K and 4–16 bar. Additionally, recent ignition delay time determinations of fuel–air mixtures without subsequent dilution from the shock tube facility of the University of Central Florida (UCF) are reevaluated. Experimental data sets are analyzed with the application of multiple chemical kinetic models. The study reveals deficiencies in the modeling of fuel-oxidizer mixtures with relatively low dilution, representative for real combustion applications. To improve the chemical kinetic modeling capabilities, the reaction model DLR Concise is updated with new insights from literature. Subsequently, the updated model is optimized with the new experimental data and additional data on ignition delay times available from literature. 373 ignition delay times of ammonia and its mixture with hydrogen are targeted for the optimization. The linear transformation model is applied to optimize the most sensitive N-chemistry reactions within their uncertainties. The new experimental data from DLR confirm the observed deviations between the reevaluated experimental data from UCF and established chemical kinetic models. The updated and optimized DLR Concise models are resolve these modeling deficiencies and consistently reproduce the new and reevaluated data from both shock tube facilities. The optimized reaction model consistently reproduces the complete targeted experimental data with a broad range of initial temperature, pressure and mixture boundary conditions. Thus, the model can reliably be applied for numerical investigations of internal combustion engine ignition processes.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105835"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154517","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":"Corrigendum to “Early-stage flame acceleration in stratified hydrogen-air mixtures: Theory and simulation” [Proc. Combust. Inst. 40 (2024) 105279]","authors":"Sébastien Missey ,&nbsp;Omar Dounia ,&nbsp;Laurent Selle","doi":"10.1016/j.proci.2025.105822","DOIUrl":"10.1016/j.proci.2025.105822","url":null,"abstract":"","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105822"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018801","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-flame interactions in lean premixed hydrogen-enriched ammonia-air flames at varying pressures","authors":"Shrey Trivedi ,&nbsp;Martin Rieth ,&nbsp;Hassan F. Ahmed ,&nbsp;Jacqueline H. Chen ,&nbsp;R. Stewart Cant","doi":"10.1016/j.proci.2025.105806","DOIUrl":"10.1016/j.proci.2025.105806","url":null,"abstract":"<div><div>Flame-flame interaction statistics are analyzed using a Direct Numerical Simulation (DNS) dataset for highly turbulent premixed flames in a temporally-evolving shear layer configuration at pressures of 1 atm and 10 atm. The fuel is a blend of ammonia, hydrogen and nitrogen, and the oxidizer is air. The critical point method is used to identify the different types of flame surface topology. Results are obtained for two different and widely-separated instants of time during the development of the flame. These two times correspond to instants with strong flame interaction with sheared turbulence and after the onset of cellular instability. The statistics indicate that there is a change in the distribution of flame-flame interaction events within the flame brush between the two different times. More events occur towards the trailing edge of the flame at the later time, and there is also a change in the type of topology observed. The changes are found to be stronger for the higher pressure case.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105806"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018804","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":"Simultaneous imaging of OH and temperature in lean premixed hydrogen/air flames: Which marker for thermodiffusive instability?","authors":"J. Bae ,&nbsp;O. Chaib ,&nbsp;L. Weller ,&nbsp;A. Moitro ,&nbsp;E.F. Hunt ,&nbsp;A.J. Aspden ,&nbsp;S. Hochgreb","doi":"10.1016/j.proci.2025.105919","DOIUrl":"10.1016/j.proci.2025.105919","url":null,"abstract":"<div><div>This study investigates thermodiffusive (TD) instabilities in lean premixed hydrogen/air flames using simultaneous measurements of hydroxyl radical (OH) via planar laser-induced fluorescence (PLIF) and temperature via Rayleigh scattering. Correlations between flame front curvature and scalar (OH and temperature) gradients as surrogates for reaction rate were assessed in the presence of TD instabilities. Experimental 2D data were compared with corresponding 2D slices extracted from 3D direct numerical simulations (DNS). In both DNS and experiments, flame fronts defined by local maximum scalar gradients (gradient-based) leads to spurious results owing to very low gradients in highly negative curvature regions associated with near-extinction by TD instability. These discontinuous fronts exhibited weaker curvature–gradient correlations than the curvature–HRR (heat release rate) correlation, indicating that scalar gradients along gradient-based fronts are inappropriate surrogates for HRR. To address this limitation, two continuous flame fronts were evaluated: (1) laminar-based front, defined using temperature progress variable at local maximum gradients of scalar by laminar flame calculation, and (2) mode-based front, defined using the most probable temperature (mode value of PDF) at local maximum gradients of temperature. These fronts capture low gradient regions and exhibit stronger correlations between curvature and a surrogate for the reaction rate in both DNS and experiment. DNS analysis revealed that flame fronts based on temperatures (from both laminar-based and mode-based methods) and OH (from laminar-based method) exhibit strong correlation with HRR, with laminar-based flame front for OH showing the highest correlation. However, in experiments, laminar-based flame front for OH correlates poorly with HRR due to spatial misalignment between the temperature and OH fields. Flame fronts by temperature from both laminar-based and mode-based methods are determined to be the most reliable HRR surrogates in experiments. This study highlights that analyzing curvature–gradient correlations under TD instability requires a continuous flame front capturing negative curvature and low gradient regions.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105919"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620463","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 of copper nitrate (Cu(NO3)2) addition on soot characteristics of ethylene pyrolysis in a laminar flow reactor","authors":"Qingyan He ,&nbsp;Teng Fei ,&nbsp;Sen Shao ,&nbsp;Qifeng Guo ,&nbsp;Xiaoqing You","doi":"10.1016/j.proci.2025.105875","DOIUrl":"10.1016/j.proci.2025.105875","url":null,"abstract":"<div><div>The effect of copper (Cu) on soot characteristics was studied by adding copper nitrate (Cu(NO₃)₂) to ethylene pyrolysis in a laminar flow reactor. The addition of Cu(NO₃)₂ altered the particle inception mechanism through the formation of “core-shell” particles with a copper “core” surrounded by carbonaceous “shell” layers, based on the results of transmission electron microscopy equipped with energy dispersive spectroscopy (TEM-EDS) and density functional theory (DFT) calculations. This phenomenon was due to the earlier nucleation of Cu (compared to soot nucleation) from the thermal decomposition of Cu(NO₃)₂. On the other hand, based on the particle size distribution results, the addition of Cu(NO₃)₂ did not enhance soot coagulation as the addition of ferrocene did in previous work, due to weaker interaction between Cu and soot precursors/particles from the DFT and molecular dynamics (MD) simulation results. In addition, thermogravimetric analysis results show that soot particles with “core-shell” structure containing Cu were easier to oxidize because they reached the maximum oxidation rate at a lower temperature than those without Cu, implying that Cu could promote soot oxidation as a catalyst.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105875"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216308","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":"Interaction and ignition process of multiple injections of oxygenated fuels in an optical, heavy-duty diesel engine","authors":"Kaylyn Buchanan ,&nbsp;Akash Dhotre ,&nbsp;Daipayan Sen ,&nbsp;Ales Srna ,&nbsp;Rajavasanth Rajasegar","doi":"10.1016/j.proci.2025.105820","DOIUrl":"10.1016/j.proci.2025.105820","url":null,"abstract":"<div><div>Poly-oxymethylene ethers (OMEs) are a class of highly oxygenated synthetic fuels that offer promising pathways for decarbonizing transportation and enhancing energy security. Their favorable ignition properties, high cetane number, and soot-free combustion characteristics make them attractive alternatives to conventional diesel. However, their lower energy density, weaker negative temperature coefficient (NTC) behavior, and rapid mixing due to fuel-bound oxygen introduce complex interactions during combustion, particularly under multiple-injection strategies common in modern diesel engines. This study investigates the ignition and combustion behavior of OMEs compared to a conventional non-oxygenated surrogate fuel (n-dodecane) under various pilot-main injection configurations using a heavy-duty, optical single-cylinder engine. A suite of diagnostics, including apparent heat release rate (AHRR) analysis and simultaneous planar laser-induced fluorescence (PLIF) imaging of formaldehyde (HCHO) and hydroxyl (OH), was employed to capture the low- and high-temperature combustion phases. Experiments were conducted across a matrix of pilot injection durations, dwell times, and EGR dilution levels to evaluate their influence on ignition delay (ID), flame structure, and heat release dynamics. Results show that OME requires longer pilot injections to overcome rapid lean-out and achieve comparable ignition assistance due to its low stoichiometric air–fuel ratio (AFR_ST) and reduced LTHR contribution. A critical minimum injection duration was identified for OME below which the pilot fails to ignite, a behavior not observed with n-dodecane. Despite this, OME displays rapid, volumetric ignition once combustion initiates, owing to favorable mixture stratification from fuel-bound oxygen. A conceptual model is proposed to distinguish ignition regimes based on pilot duration and fuel oxygenation level, explaining the interplay between entrainment-driven mixing, HTHR suppression, and reactive zone formation. The findings enhance understanding of the underlying physics governing multiple injections and provide guidance for optimizing pilot strategies when adapting diesel engines to oxygenated fuels like OME.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105820"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145007767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of water vapor on nitriding of stainless steel walls induced by ammonia flames","authors":"Yujian Xing,&nbsp;Minhyeok Lee,&nbsp;Yuji Suzuki","doi":"10.1016/j.proci.2025.105831","DOIUrl":"10.1016/j.proci.2025.105831","url":null,"abstract":"<div><div>Ammonia is a promising candidate fuel for future carbon-free energy systems. However, significant interactions between ammonia flames and metal walls in combustors result in “unwanted” nitriding, compromising safe operation and shortening the lifespan of combustion systems. The substantial water vapor generated during ammonia combustion further influences this flame-wall interaction. This study examines the effect of water vapor on two interconnected processes: the heterogeneous decomposition of ammonia and the nitriding of stainless steel induced by ammonia flames. Ammonia conversion ratios due to heterogeneous decomposition on stainless steel surfaces were measured in a flow reactor under varying water vapor concentrations, and the mechanisms underlying the impact of water vapor on both surface reactivity and surface nitriding were examined. Additionally, the effect of water vapor on nitriding induced by ammonia flames was investigated. The findings confirm that the oxidation effect of water vapor reduces surface reactivity for heterogeneous ammonia decomposition, making it the primary factor behind the hindering effect on nitriding during ammonia combustion.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105831"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104447","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":"Large eddy simulation of transient leading edge propagation in a turbulent lifted hydrogen jet flame","authors":"Christoph D.K. Schumann ,&nbsp;James C. Massey ,&nbsp;Caleb J. Li ,&nbsp;Nedunchezhian Swaminathan","doi":"10.1016/j.proci.2025.105827","DOIUrl":"10.1016/j.proci.2025.105827","url":null,"abstract":"<div><div>A lifted turbulent jet flame involves partial premixing and exhibits a tribrachial flame structure at its leading edge (LE). Its propagation from the initial sparking location towards the final stabilisation height has rich physics. Large eddy simulation (LES) with flamelet-based reaction rate closure for partially premixed combustion is employed to study this propagation. The initial kernel grows radially in the rich region, and it is skewed by the oncoming flow as it is convected downstream. An LE is formed as the flame propagates radially into lean mixtures with low streamwise velocities. This LE encounters the lean limit, while a core flame continues to develop closer to the jet centreline, where the mixture reactivity and flow velocity are significantly large. Eventually, this core flame overtakes the LE in the lean mixture and upstream propagation ensues. The LE propagates mostly in the lean mixture, as the streamwise velocity in the vicinity of the jet core is high, although occasional rapid propagation is observed as the core flame encounters highly reactive mixture due to turbulence. Hence, the two flame branches are competing to form the LE. This behaviour is quite different to propagation in a lifted methane jet flame due to the increased reactivity and wider flammability limits of hydrogen. Turbulence plays a fundamental role during propagation for the formation of new upstream flame kernels, which evolve from pockets of hot reactants and fresh mixture. These kernels may be convected downstream causing the LE to recede. Eventually, the LE reaches a stationary state, and the flame root stabilises at a position where the burning mass flux is balanced by the flame normal advective mass flux. The LE does not encounter the value of the extinction dissipation rate for the mixture fraction during its evolution towards the stabilisation and at this location.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105827"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262368","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}