Proceedings of the Combustion Institute最新文献

{"title":"New mixture rules affect kinetic predictions of energetic material combustion: A case study for RDX, ammonium perchlorate, and nitroglycerin","authors":"Patrick J. Singal,&nbsp;Avery F. Rambur,&nbsp;Rodger E. Cornell,&nbsp;Michael P. Burke","doi":"10.1016/j.proci.2026.106257","DOIUrl":"10.1016/j.proci.2026.106257","url":null,"abstract":"<div><div>Recent theoretical and computational advancements have unlocked new possibilities for the consideration of mixture dependence of complex-forming reactions. Previous work has shown that implementation of the new linear-mixture-rule-in-reduced-pressure (LMR-R) along with ab initio temperature-dependent third-body efficiencies has a substantial impact on combustion predictions of fuel/air mixtures. Compared to combustion in air, whose primary constituents (N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, O<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>) have third-body efficiencies close to unity, combustion of monopropellants often produces mixtures almost exclusively composed of species that are polyatomic, polar, or both and therefore would tend to have high third-body efficiencies—such that composition dependence may be equally (if not more) significant. This paper presents the first implementation of LMR-R and accompanying third-body efficiencies for energetic material combustion. The impact of composition dependence is illustrated through deflagration simulations for cyclotrimethylene trinitramine (RDX), ammonium perchlorate (AP), and nitroglycerin (NG), three common energetic materials whose kinetic mechanisms are the subject of extensive previous and ongoing investigation. Our present analysis reveals that consideration of mixture rules has a major effect on predictions of burn rates and species profiles, also impacting features that describe flame thicknesses and dark zone structures. Importantly, the results demonstrate the importance of proper treatment of composition dependence in future energetic material models and motivate future characterization of different complex/collider pairs than those important to fuel/air combustion.</div><div><em>Novelty and significance statement:</em> This study presents the first systematic investigation of the impact of rate-constant composition dependence on deflagration predictions for energetic materials. Consistent with the abundance of species with high third-body efficiencies encountered in such scenarios, composition dependence is found to significantly influence predictions of burn rates and species profiles, which in turn have implications for flame thicknesses and dark zone structures. Based on these results, we recommend future energetic material models include systematic treatment of composition dependence and we identify specific complex/collider pairs worth further fundamental characterization.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106257"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148995086","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 pressure on the chemical sooting structure of equi-diffusive counterflow diffusion flames","authors":"Rajat Sawanni,&nbsp;Ömer L. Gülder","doi":"10.1016/j.proci.2026.106528","DOIUrl":"10.1016/j.proci.2026.106528","url":null,"abstract":"<div><div>The effects of pressure on the chemical sooting structure of equi-diffusive soot formation (SF) counterflow diffusion flames (CDF) are explored in a combined experimental and numerical study over pressures ranging from 1 bar to 6 bar. Experiments preserve the diffusive flame structure and carbon flux at increasing pressures and utilize measurements of soot concentrations, dispersion exponents and soot production rates. Numerical simulations are completed in OpenSMOKE++ with detailed <span><math><mrow><msub><mrow><mtext>C</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mo>−</mo><msub><mrow><mtext>C</mtext></mrow><mrow><mtext>16</mtext></mrow></msub></mrow></math></span> chemistry, lumped PAH consideration up to C₁₆₀, sectional soot model and tracking of the C/H ratio in particulates. Network-based tools are utilized to study the organization and evolution of carbon routing pathways. Results show that for equi-diffusive flames, soot concentration increases with residence time and pressure, whereas soot production rates are influenced only by pressure. Soot C/H ratio is observed to increase with pressure using numerical and experimental methods, but numerical solutions underestimate the increase in hydrogen abstraction reactions. The soot-forming network undergoes a percolation-like organization of its pathways before soot inception. The network then continues to grow by adding connections through its influential nodes. Acetylene is identified as a highly influential node in the carbon transfer graph, with its influence increasing with pressure.</div><div><em>Novelty and significance statement:</em> This work advances understanding of the pressure effects on soot formation chemistry using a combined experimental and numerical work in CDFs. Utilization of multi-wavelength absorption-emission diagnostics for the measurement of soot concentration, production rates and maturity provides a rich dataset to the limited body of high-pressure sooting CDF data. Moreover, the study advances soot chemistry analysis by casting it as a chemical reaction network (CRN) and extending pathway analysis beyond a single dominant pathway to a graph-theoretic framework that elucidates soot-reaction topology.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106528"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149003794","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":"Theoretical kinetics of HO2 + buten-4-ol-3 radicals and improved predictions for 1,3-butadiene combustion","authors":"Junfeng Bai,&nbsp;Chong-Wen Zhou,&nbsp;Lei Zhou","doi":"10.1016/j.proci.2026.106376","DOIUrl":"10.1016/j.proci.2026.106376","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This work investigates the kinetics and thermodynamics of HO&lt;sub&gt;2&lt;/sub&gt; radical addition to the resonantly stabilized buten-4-ol-3 radical, a key reaction in low-temperature 1,3-butadiene oxidation. High-level theoretical methods, including ROCCSD(T)/CBS energy calculations and variable reaction coordinate transition state theory (VRC-TST), were employed to characterize the potential energy surfaces (PESs) and compute pressure- and temperature-dependent rate constants for the addition and subsequent decomposition pathways. The central addition of HO&lt;sub&gt;2&lt;/sub&gt; to buten-4-ol-3 was identified as the most favorable pathway, leading primarily to the formation of 3-oxyl-1-buten-4-ol radical at higher temperatures. Thermochemical properties for key species are computed using composite methods and show good agreement with available literature data. The newly calculated kinetic and thermodynamic parameters were incorporated into the NUIGMech1.3 mechanism. Model validation against ignition delay time (IDT) data from a rapid compression machine (RCM) and species profiles from a jet-stirred reactor (JSR) shows that the updated mechanism improves predictions, particularly for IDTs between 770 and 900 K and for acrolein (C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;3&lt;/sub&gt;CHO) formation in JSR experiments. Sensitivity and flux analyses reveal that the enhanced model performance stems from the competition between HO&lt;sub&gt;2&lt;/sub&gt; and O&lt;sub&gt;2&lt;/sub&gt; addition to buten-4-ol-3, which reduces system reactivity by decreasing the flux through a highly promoting O&lt;sub&gt;2&lt;/sub&gt; addition pathway. The original mechanism's underestimation of peroxide decomposition rate constants by over five orders of magnitude artificially enhanced this promoting pathway, leading to overpredicted reactivity. This study provides crucial fundamental data, significantly improving the predictive capability of combustion models for 1,3-butadiene—a key soot precursor—and demonstrating the necessity of high-level theoretical kinetics for accurate combustion chemistry modeling.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Novelty and significance statement&lt;/h3&gt;&lt;div&gt;This work presents the first high-level theoretical kinetics investigation of HO&lt;sub&gt;2&lt;/sub&gt; addition to the buten-4-ol-3 radical, a critical sub-mechanism in 1,3-butadiene combustion. Using ROCCSD(T)/CBS methods and variable reaction coordinate transition state theory (VRC-TST), we provide accurate pressure-dependent rate constants for barrierless addition and decomposition pathways, moving beyond prior estimations. Central addition is identified as the dominant pathway, with its competition against O&lt;sub&gt;2&lt;/sub&gt; addition representing a completely new mechanistic insight. The updated kinetics systematically correct model over-prediction of reactivity at 770–900 K and successfully reproduce experimental C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;3&lt;/sub&gt;CHO profiles. Implemented in NUIGMech1.3, these parameters enhance predictive capability for soot formation studies and larger hydrocarbon mechanisms,","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106376"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148958413","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":"Quantifying facility-induced variability and uncertainty in RCM sampling","authors":"Buyao Ran,&nbsp;Yingtao Wu,&nbsp;Yang Li,&nbsp;S. Scott Goldsborough,&nbsp;Song Cheng","doi":"10.1016/j.proci.2026.106361","DOIUrl":"10.1016/j.proci.2026.106361","url":null,"abstract":"&lt;div&gt;&lt;div&gt;While facility effects have been widely examined for ignition delay measurements, their impact on sampling measurements in RCMs remain completely unexplored. Additionally, whether the conventional approach for estimating the dilution ratio by dead volume in the sample probe is sufficient remains an open question. These important questions are answered for the first time in this study, which is achieved via a systematic CFD investigation of RCM samplings with four different RCM configurations across a wide range of thermodynamic conditions (&lt;em&gt;T&lt;sub&gt;c&lt;/sub&gt;&lt;/em&gt; = 810–870 K, &lt;em&gt;p&lt;sub&gt;c&lt;/sub&gt;&lt;/em&gt; = 20–80 bar) and sampling times. Facility effects on RCM sampling results are found to be significant, with greater impacts observed at higher compressed temperatures and pressures and during the early stages of the ignition delay period. Maximum deviations in sampled concentrations between different RCM configurations reach over 73% in sampled mass fraction, significantly exceeding the corresponding deviations in ignition delay times under the same conditions. The conventional approach for correcting dilution effects introduces substantial errors in estimating both the dead volume gas temperature (e.g., −220 to 150 K) and dead volume species concentration (e.g., up to 80% in mass fraction). This results in errors in the calculated dilution ratio (reaching over 25% under the conditions investigated), leading to additional uncertainties in RCM speciation. Flow field analyses reveal that sampling facility effects are driven by unique mechanisms beyond that for IDT measurements, leading to different sampling results even under identical core gas conditions where facility effects on IDT are zero. These findings emphasize the necessity of thoroughly investigating facility effects on RCM sampling and highlight the importance of accurately correcting for dead volume properties in the sampling probe and its dilution to improve the reliability of future RCM sampling studies.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Novelty and significance statement&lt;/h3&gt;&lt;div&gt;This work is the first study that: (1) quantifies the facility effects on sampling in RCMs; (2) characterizes the capability of the community-wide adopted approach for estimating the dead volume property and dilution in sampled gases, where we found that the conventional approach leads to significant errors in estimating dead volume temperature, concentration, and dilution ratio; and (3) reveals the uncertainties that dilution effects of dead volume can lead into the sampling results across a wide range of thermodynamic conditions and sampling times. The results enable a systematic CFD framework to quantify and correct for dilution and thermal deviations in RCM sampling. By addressing the impact of dead volume dilution at various crevice geometry and sampling timing, the work improves the accuracy and reliability of RCM sampling measurements. The findings are directly relevant to ongoing efforts to standardize sampling","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106361"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951576","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 comprehensive PAH mechanism for ammonia–hydrocarbon co-combustion","authors":"Qi Wang,&nbsp;Junjun Guo,&nbsp;Hong G. Im,&nbsp;S. Mani Sarathy","doi":"10.1016/j.proci.2026.106355","DOIUrl":"10.1016/j.proci.2026.106355","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Ammonia (NH&lt;sub&gt;3&lt;/sub&gt;) is a promising hydrogen carrier that can facilitate the near-term energy transition through co-firing with hydrocarbon fuels. To predict the co-combustion of ammonia with hydrocarbon, however, many important chemical pathways and their reaction rates are not clearly understood. In this work, theoretical calculations were conducted for the important reactions of the propargyl radical (C&lt;sub&gt;3&lt;/sub&gt;H&lt;sub&gt;3&lt;/sub&gt;) with hydrogen cyanide (HCN), and a comprehensive kinetic mechanism for NH&lt;sub&gt;3&lt;/sub&gt;-doped hydrocarbon combustion is developed. The potential energy surfaces for the reactions of two resonance forms of C&lt;sub&gt;3&lt;/sub&gt;H&lt;sub&gt;3&lt;/sub&gt; with HCN were characterized using high-level &lt;em&gt;ab initio&lt;/em&gt; method. These reactions lead to the formation of both acyclic molecules and cyclic radicals, including pyrrolyl species. Rate constants were subsequently determined using the Rice–Ramsperger–Kassel–Marcus one-dimensional master equation approach, and thermodynamic properties were also calculated. Following this, a new kinetic model was developed incorporating updated ammonia pyrolysis and oxidation chemistry, together with detailed interactions between nitrogen-containing species and C&lt;sub&gt;1&lt;/sub&gt;–C&lt;sub&gt;3&lt;/sub&gt; hydrocarbons and polycyclic aromatic hydrocarbons (PAHs). The mechanism was validated against 12 literature experimental datasets, including ignition delay times, laminar burning velocities, and speciation profiles measured in ideal reactors and one-dimensional flames over a wide range of conditions. Overall, the proposed mechanism reproduces these experimental observations well. Sooting flame simulations of ammonia-doped ethylene counterflow diffusion flames further show that the formation of small aromatics such as benzene is not significantly affected by NH&lt;sub&gt;3&lt;/sub&gt; substitution, while the growth of larger PAHs is suppressed. This behavior is attributed to the formation pathways of nitrogen-containing polycyclic aromatic compounds (NPACs). As a result, the model successfully reproduces the experimentally observed reduction in PAH and soot formation with increasing NH&lt;sub&gt;3&lt;/sub&gt; addition. These results highlight the important role of nitrogen–carbon interaction chemistry in suppressing PAH growth and soot formation in ammonia–hydrocarbon combustion systems.&lt;/div&gt;&lt;div&gt;&lt;em&gt;Novelty and significance statement:&lt;/em&gt; Recent theoretical studies of nitrogen–carbon (N&lt;img&gt;C) interaction chemistry have identified several important pathways (&lt;em&gt;e.g.,&lt;/em&gt; the formation of nitrogen-containing polycyclic aromatic compounds) that contribute to the chemical effects of ammonia (NH&lt;sub&gt;3&lt;/sub&gt;) on PAH and soot formation. A comprehensive PAH mechanism is therefore crucial for accurate prediction in NH&lt;sub&gt;3&lt;/sub&gt;-hydrocarbon co-combustion systems. In this work, a detailed PAH mechanism for NH&lt;sub&gt;3&lt;/sub&gt;-hydrocarbon co-combustion was developed based on &lt;em&gt;ab initio&lt;/em&gt; theoretical calculations and the latest literature","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106355"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148951577","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":"Interplay of alkyl-substituted aromatics in ternary aromatic/n-heptane blends: Shock tube study toward SAK surrogates","authors":"Subharaj Hossain,&nbsp;Raghu Sivaramakrishnan,&nbsp;Patrick T. Lynch,&nbsp;Eric K. Mayhew,&nbsp;Kenneth Brezinsky","doi":"10.1016/j.proci.2026.106626","DOIUrl":"10.1016/j.proci.2026.106626","url":null,"abstract":"<div><div>The oxidation behavior of multi-aromatic/n-alkane blends was investigated to elucidate cross-interactions among alkyl-substituted aromatics and their collective influence on fuel reactivity and synthetic aromatic kerosene (SAK) surrogate development. Shock tube speciation experiments at high pressure (∼50 atm) were performed for ternary blends of 1,2,4-trimethylbenzene (TMB124), 3-ethyltoluene (ET), 3-n-propyltoluene (PT), and n-heptane, namely HETTMB (TMB124/ET/n-heptane), HPTTMB (TMB124/PT/n-heptane), and HETPT (ET/PT/n-heptane). Gas chromatographic analysis quantified over 30 products, enabling detailed comparisons with kinetic modeling results. Simulations using the CRECK_ETPT mechanism and its extended version, CRECK_ETPT_Ext_Crs, captured major speciation trends and clarified the role of resonance-stabilized aromatic radicals (RSRs). ET- and PT-derived radicals were found to enhance reactivity through H-abstraction from n-heptane and additional radical generation from decomposition pathways, whereas the TMB124-derived radical RC₉H₁₁ behaved primarily as a radical sink. The analysis also showed that meta-substitution affects key aromatic pathways, particularly those associated with benzene formation, highlighting limitations of lumped ortho-derived chemistry for these systems. These findings provide a mechanistic basis for developing chemically consistent multi-aromatic SAK surrogate mechanisms that explicitly account for inter-aromatic radical interactions.</div><div><strong>Novelty and significance statement</strong></div><div>This study presents the first comprehensive and systematic examination of interactions among alkyl-substituted aromatics during oxidation in multicomponent mixtures representative of synthetic aromatic kerosene (SAK)-like fuel systems. High-pressure shock tube speciation experiments, coupled with kinetic modeling, show that cross-reactions among resonance-stabilized aromatic radicals (RSRs) can subtly yet mechanistically influence fuel reactivity and product formation. The results demonstrate that the oxidation behavior of multi-aromatic blends cannot be inferred from binary systems alone and highlight the importance of including aromatic–aromatic radical cross-reaction pathways in detailed kinetic mechanisms. Understanding these interactions is essential for developing predictive kinetic models of practical fuels and synthetic aviation fuel surrogates, as they provide deeper mechanistic insight into alkyl-aromatic oxidation chemistry.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106626"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149153647","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":"Investigation of n-dodecane, 1-methylnaphthalene and i-octane combustion in a burner stabilized surrogate flame","authors":"Ewald Keksel,&nbsp;Nico Goncz,&nbsp;Gongtong Wang,&nbsp;Munko Gonchikzhapov,&nbsp;Tina Kasper","doi":"10.1016/j.proci.2026.106393","DOIUrl":"10.1016/j.proci.2026.106393","url":null,"abstract":"<div><div>Fuel surrogates emulate the combustion properties of practical fuels using defined hydrocarbon mixtures. This study examines a ternary surrogate composed of n-dodecane, 1-methylnaphthalene and i-octane in laminar,</div><div>low-pressure, premixed flames. Evaporation and delivery are reliable, and stable premixed flames are sustained on a matrix burner, apparently resulting in the first report for this blend. Flame-sampling electron ionization time-of-flight mass spectrometry in combination with flame temperature measurements yield species and temperature profiles under fuel-rich, stoichiometric and fuel-lean conditions that serve as quantitative targets for mechanism development. In addition, fuel profiles and temperature profiles of neat n-dodecane and neat i-octane flames are measured for comparison. The data have been meticulously checked for influence of dissociative ionization and fragment overlap caused by electron ionization and are reported including uncertainties. Quantification is based on calibration measurements. Numerical simulations performed with three different reaction mechanisms reproduce overall trends and expose systematic discrepancies to the measurements. Mechanistic analyses isolate controlling reaction classes and rate limiting steps across equivalence ratios and highlight coupling between low temperature and radical fuel chemistry, aromatic growth from 1-methylnaphthalene fragments and branched alkane reaction pathways from i-octane.</div></div><div><h3>Novelty and significance statement</h3><div>Experimental data for multicomponent surrogate flames remain limited, particularly for blends combining aliphatic, branched and aromatic fuel components with different reactivities and volatilities. This work stabilizes laminar, low-pressure flames of a new Diesel oriented surrogate consisting of n-dodecane, i-octane and 1-methylnaphthalene on a matrix burner. Unlike i-octane, 1-methylnaphthalene has not been stabilized in a neat flame on a laminar, flat flame burner, so its chemistry is investigated here for the first time within a stabilized surrogate flame. For three equivalence ratios, major species and key intermediates including radicals are quantified by electron ionization molecular beam mass spectrometry despite challenges from dissociative ionization of these large fuels. The resulting datasets provide a new and reliable target for validating detailed mechanisms and capture diffusion effects and radical chemistry.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106393"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149153693","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":"Eigenvalue-based linear stability analysis of intrinsic instabilities in laminar flames","authors":"Thomas Ludwig Kaiser,&nbsp;Peter Munch,&nbsp;Sandra May,&nbsp;Thorsten Zirwes","doi":"10.1016/j.proci.2026.106000","DOIUrl":"10.1016/j.proci.2026.106000","url":null,"abstract":"<div><div>Intrinsic instabilities of laminar premixed flames play an important role in the dynamics of hydrogen combustion and in the development of predictive models for reacting flows. However, determining their DRs typically relies either on simplified analytical descriptions of the flame front or on computationally expensive direct numerical simulations (DNS). Motivated by this challenge, this work develops a generalized eigenvalue problem–based linear stability analysis (GEVP-LSA) framework that predicts the growth rates and spatial structure of intrinsic flame instabilities directly from the linearized governing equations of a 1D base flame. The approach is first validated using the classical Darrieus–Landau configuration, where the numerical results reproduce the analytical DR and eigenmode structure. The framework is then applied to a model flame of finite thickness governed by the reactive Navier–Stokes equations. The resulting DRs and perturbation fields show excellent agreement with corresponding DNS results while reducing the computational effort by a factor of <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>8</mn></mrow></msup></mrow></math></span>. The proposed method provides an efficient and accurate tool for studying intrinsic instabilities in unity-Lewis-number flames and offers a scalable foundation for future stability analyses of more complex reacting-flow configurations relevant to combustion modeling and large-eddy simulations, including thermodiffusive effects.</div><div><em>Novelty and significance statement:</em> Existing approaches for determining dispersion relation (DRs) of intrinsic flame instabilities fall into two categories. Analytical approaches provide valuable physical insight but rely on simplifying assumptions that often lead to quantitatively inaccurate predictions. Second, Direct Numerical Simulations (DNSs) can determine DRs with high accuracy; however, their high computational cost limits exploration of large parameter spaces.</div><div>This work establishes a third approach in which the stability problem is formulated directly as a generalized eigenvalue problem derived from the linearized 1D reactive Navier–Stokes equations. This formulation enables the direct computation of instability growth rates and eigenmodes while retaining the full governing physics and reducing computational cost by up to eight orders of magnitude compared to DNS. The current framework systematic investigations of intrinsic flame instabilities in unity-Lewis-number flames and lays the groundwork for studying phenomena such as thermodiffusive instabilities with DNS-level accuracy but at a fraction of the computational cost.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106000"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148567013","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":"Particle-resolved characterization of micron-sized aluminum particle combustion in high-temperature H2O/N2 flows","authors":"Can Ruan,&nbsp;Nick Häuser,&nbsp;Shuguo Shi,&nbsp;Justin Knubel,&nbsp;Feier Chen,&nbsp;Yuhang Li,&nbsp;Tao Li,&nbsp;Christian Hasse,&nbsp;Andreas Dreizler","doi":"10.1016/j.proci.2026.106008","DOIUrl":"10.1016/j.proci.2026.106008","url":null,"abstract":"<div><div>The combustion of micron-sized aluminum (Al) particles in high-temperature steam (H₂O) has been recently proposed as a promising approach for simultaneous hydrogen and power generation without the emissions of carbon dioxide (CO₂). However, experimental investigations with well-characterized boundary conditions are currently scarce, limiting the development of predictive models and the design of practical reactors. By employing multiple <em>in-situ</em> optical diagnostics techniques, including one-dimensional (1D) Raman/Rayleigh spectroscopy, high-speed luminosity and diffuse back-illumination (DBI) imaging, the ignition and combustion mechanisms of micron-sized Al particles in high-temperature H₂O/N₂ laminar flows were investigated. It was shown that the majority of Al was consumed within phases featuring asymmetric combustion due to the fast-growing alumina (Al₂O₃) cap and the frequent adhesion of the produced Al₂O₃ droplets on the parent droplet surface. In addition, the widely encountered micro-explosion phenomenon close to the end of the combustion was successfully visualized with high spatiotemporal resolution, providing <em>in-situ</em> evidence to support that this explosion was caused by the rapid evaporation of the residual Al inside the Al₂O₃ shell. Particle-resolved burning time measurements indicated that the decrease of the environment temperature and H₂O content enhanced the role of asymmetric combustion. This trend might result from a reduced stand-off distance of the Al₂O₃ condensation layer, which increased the likelihood of the condensed Al₂O₃ depositing to the Al droplet surface. Such attachment could promote the growth of the Al₂O₃ cap, thereby decreasing the effective area available for Al evaporation and strengthening the asymmetric combustion process. Finally, a new correlation of the burning time, accounting for the localized temperature, major species (H₂O and N₂) concentrations, and the particle diameter, was proposed.</div></div><div><h3>Novelty and significance statement</h3><div>The lack of experimental studies with pure steam (without other oxidizers such as CO₂, O₂, etc.) at high-temperatures has substantially hindered the development of predictive models for Al-steam reactions. This paper addresses this gap by implementing multi-parameter <em>in-situ</em> optical diagnostics to systematically investigate the ignition and combustion behavior of micron-sized Al particles in well-characterized H₂O/N₂ flows. The reported combustion dynamics and datasets provide new insights for improving Al particle combustion modeling.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106008"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148567256","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":"Mechanism of gliding-arc-assisted combustion in a tandem dual-cavity scramjet combustor","authors":"Zihao Zhang,&nbsp;Shuaijia Shao,&nbsp;Mingbo Sun,&nbsp;Yangyang Ban,&nbsp;Zhan Chen,&nbsp;Tao Tang,&nbsp;Yifu Tian,&nbsp;Fan Zhang,&nbsp;Jianjun Wu,&nbsp;Jiajian Zhu","doi":"10.1016/j.proci.2026.106018","DOIUrl":"10.1016/j.proci.2026.106018","url":null,"abstract":"<div><div>In the tandem dual-cavity scramjet combustor at the Mach 2.52 inflow condition, a detailed mechanism investigation of the plasma-assisted combustion process is conducted using high-speed flame chemiluminescence, schlieren imaging, and numerical simulations. Experiments show a weak flame state in the single rear cavity at a fuel injector ratio of approximately 3:1. In the presence of the gliding arc plasma, a stronger global flame and a stable state in the dual cavity are achieved. The flame intensity and heat release rate are significantly increased. OpenFOAM coupled with ZDPlasKin is applied in numerical simulations to calculate the detailed three-dimensional plasma-kinetics mechanism of flow combustion and to reveal the combustion mechanism. Under the influence of the gliding-arc plasma, the kernel generates hot bubbles and modifies the flow-field characteristics of the shear layer above and within the front cavity. This facilitates the further transport of the kernel and flame. The kernel flows backward from the bottom of the cavity to the leading-edge corner recirculation zone, where it develops into a global flame connecting the two cavities. At the same time, the high turbulence shear-layer over the rear cavity is thickened and lifted. Detailed chemical reaction kinetics in the plasma region are investigated. The heat release process is dominated by the de-excitation reactions of N₂* and O*, with a contribution rate two orders of magnitude higher than that of typical combustion elementary reaction heat release rates, such as the consumption of CH₂ and OH.</div></div><div><h3>Novelty and significance statement</h3><div>Through experiments and three-dimensional, detailed chemical-kinetics numerical simulations, this work innovatively investigated the mechanism and detailed chemical kinetics of the gliding-arc plasma-assisted supersonic combustion process in the tandem dual-cavity combustor. The plasma kinetics and main excited-state components contributing to heat release are revealed, along with the elementary reactions involved. The work on simulating 3-D detailed plasma dynamics for the tandem dual-cavity combustor configuration represents the most innovative contribution.</div><div>This work guides the design and application of dual-cavity scramjet combustors. By applying gliding-arc plasma, supersonic combustion is enhanced in the weak-flame case. The verified comparison of experimental and computational flow-field characteristics and pressure distributions demonstrates the reliability of using OpenFOAM coupled with ZDPlasKin for three-dimensional simulations of plasma-kinetics reaction flows.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"42 ","pages":"Article 106018"},"PeriodicalIF":4.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148567516","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}