Proceedings of the Combustion Institute最新文献

{"title":"Simultaneous NH/NO PLIF measurements in plasma-assisted ammonia and ammonia/hydrogen swirling flames","authors":"Hao Tang,&nbsp;Evangelos Chatziandreou,&nbsp;Griffin Rahn,&nbsp;Bo Peng,&nbsp;Wenting Sun","doi":"10.1016/j.proci.2025.105789","DOIUrl":"10.1016/j.proci.2025.105789","url":null,"abstract":"<div><div>This study investigates simultaneous NH/NO planar laser-induced fluorescence (PLIF) measurements in plasma-assisted NH₃/air and NH₃/H₂ (9:1 volume ratio)/air flames at equivalence ratios of <span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>75</mn></mrow></math></span>, <span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>94</mn></mrow></math></span>, and 1.1. A single dye laser system, equipped with frequency-doubling and mixing units, was employed to simultaneously generate excitation wavelengths near <span><math><mrow><msub><mrow><mi>λ</mi></mrow><mrow><mtext>NO</mtext></mrow></msub><mo>=</mo><mn>236</mn><mo>.</mo><mn>214</mn></mrow></math></span> <!--> <!-->nm and <span><math><mrow><msub><mrow><mi>λ</mi></mrow><mrow><mtext>NH</mtext></mrow></msub><mo>=</mo><mn>303</mn><mo>.</mo><mn>545</mn></mrow></math></span> <!--> <!-->nm, enabling optimized excitation of NO and NH fluorescence, respectively. Across all equivalence ratios, plasma was found to enhance NO and NH concentrations in both NH₃/air and NH₃/H₂/air flames in the near field, although NH enhancement was less pronounced in the NH₃/H₂/air cases. In NH₃/air flames, NO concentrations decreased faster downstream with plasma activation, whereas in NH₃/H₂/air flames, NO levels remained relatively unchanged regardless of plasma activation. For NH₃/air flames, plasma could enhance atomic O production therefore acceleration of NH₃/NH₂/NH and form OH at the same time. The enhanced OH levels further promote NH production via NH₂ <span><math><mo>+</mo></math></span> OH <span><math><mo>→</mo></math></span> NH <span><math><mo>+</mo></math></span> H₂O in NH₃/air flames, though this effect is less significant in NH₃/H₂/air flames owing to the contribution of H₂ on radical pool buildup and less NH₃ availability in NH₃/H₂/air mixtures. In the downstream region, the reaction NH <span><math><mo>+</mo></math></span> NO <span><math><mo>→</mo></math></span> N₂H₂ <span><math><mo>+</mo></math></span> H plays a key role in reducing NO emissions in NH₃/air flames with plasma activation. These findings provide new insights into plasma-enhanced NH₃ flame chemistry and pollutant formation pathways, contributing to the development of cleaner and more efficient NH₃-based combustion technologies.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105789"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852892","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":"Combustion kinetics of amines: Exploring hydrogen atom abstraction reactions from primary amines by ṄH2 radicals","authors":"Mingxia Liu ,&nbsp;Minxing Chen ,&nbsp;Ruiyang Fan ,&nbsp;Yansen Liao ,&nbsp;Jingbo Wang ,&nbsp;Chong-Wen Zhou ,&nbsp;Zhen-Yu Tian","doi":"10.1016/j.proci.2025.105832","DOIUrl":"10.1016/j.proci.2025.105832","url":null,"abstract":"<div><div>Amines are often used as model compounds to investigate the combustion chemistry of the nitrogen-containing compounds in biomass. The amino radical (ṄH₂) plays a pivotal role in the initial stages of biomass pyrolysis and oxidation. To gain insight into nitrogen conversion chemistry, it is necessary to understand the cross-reactions between amine-bearing molecules and ṄH₂ radicals. In this study, a comprehensive investigation was performed on the chemical kinetics of hydrogen atom abstraction reactions of twelve C₁ – C₅ amines by ṄH₂ radicals. Geometry optimizations and frequency analyses were conducted for all species involved in fifty reaction channels at the M06–2X/6–311++<em>G</em>(d,p) level of theory. Single-point energies were calculated at the QCISD(T)/CBS level of theory, and subsequently corrected by zero-point energy. Conventional transition state theory with asymmetric Eckart tunneling corrections and the one-dimensional hindered rotor approximation was used to calculate the high-pressure limit rate constants for these targeted reactions over a temperature range of 500 – 2000 K. The average rate constants for hydrogen atom abstraction from primary, secondary, and tertiary carbons at different positions relative to the amino functional group, labelled as α, β, γ, and δ, were provided, following the order: primary &lt; secondary &lt; tertiary. The hyperconjugation effect of the amino group on the <em>α</em> C–H bond lowers the electronic energy barrier; therefore, rate constants for abstraction from the <em>α</em> C–H site largely dominate. A comparison of the average rate constants for amines and the previous studies on alkanes, alcohols, ethers, and esters was performed to reveal the influence of different functional groups on kinetic parameters. The updated rate constants were then employed in the target fuel mechanism to investigate their effect on the prediction of species concentrations associated with H-atom abstraction reactions in a jet-stirred reactor.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105832"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145007768","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":"Fuel blend and secondary air injection effects on the stability, morphology, and dynamics of two-stage NH3-CH4/H2 swirl flames","authors":"Cristian D. Avila Jimenez ,&nbsp;Andrew Macfarlane ,&nbsp;Felipe Campuzano ,&nbsp;Santiago Cardona ,&nbsp;Matthew Dunn ,&nbsp;Thibault F. Guiberti ,&nbsp;Assaad R. Masri ,&nbsp;William L. Roberts","doi":"10.1016/j.proci.2025.105817","DOIUrl":"10.1016/j.proci.2025.105817","url":null,"abstract":"<div><div>Ammonia (NH₃) has been identified as a potential carbon-free fuel to decarbonize power generation by gas turbines. However, challenges associated with flame stabilization and emissions must be solved. Two-stage, rich-lean combustion is a promising strategy that requires fine control of the secondary stage parameters, where air is injected to oxidize the remaining unburned fuel from the rich primary stage. This study investigates the effects of the fuel blend composition (NH₃-CH₄ and NH₃-H₂), NH₃vol fraction (X_NH3), primary (<em>ϕ_primary</em>) and global (<em>ϕ_global</em>) equivalence ratios, and geometry of the secondary air injection (number and diameter of holes) on the morphology of the lean secondary and rich-premixed primary flames, and primary flame stability and dynamics. Experiments are conducted with a lab-scale piloted burner inspired by the AE-T100’s micro gas turbine burner. By increasing the secondary air flow rate (<em>Q_sec</em>), <em>ϕ_global</em> varied from 0.91 down to a value that produces primary flame morphology changes (<em>ϕ_global,FC</em>), and then to a minimum value that eventually led to flame instability followed by blowout (<em>ϕ_global,BO</em>). These thresholds were found to depend on fuel composition and air injection geometry. High-speed chemiluminescence imaging of NH₂* combined with Dynamic Mode Decomposition (DMD) revealed distinct instability mechanisms: CH₄-blended flames exhibited longitudinal pulsations, while H₂-blended flames showed a rotating inner core that reignites upstream reactants. These instabilities are linked with a combustion regime transition for the secondary combustion zone, from diffusion-like to premixed-like (or partially premixed), indicative of an optimum <em>ϕ_global</em> for each geometry. Finally, increasing the number of secondary air holes (while keeping diameter constant) extended flame stability to leaner <em>ϕ_global</em>. Data showed that the geometry of the secondary air injection is more important for stability than other varied parameters, a valuable finding for the design of future two-stage, rich-lean NH₃ burners.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105817"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144886775","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":"Shock-tube and modeling study of trichloromethane pyrolysis and trichloromethane/methane oxidation using a HCl laser absorption diagnostic","authors":"Claire M. Grégoire,&nbsp;Eric L. Petersen","doi":"10.1016/j.proci.2025.105823","DOIUrl":"10.1016/j.proci.2025.105823","url":null,"abstract":"<div><div>Chlorinated hydrocarbon burning characteristics when involved in incineration processes and when formed during rocket propellant combustion are not well understood, and evaluations of their chemical kinetics mechanisms at high temperatures are limited by the scarce experimental measurements. The pyrolysis of trichloromethane (CHCl₃) and the oxidation of CHCl₃/methane (CH₄) at ϕ = 1.0, both highly diluted in 99.5 % Ar, were investigated behind reflected shock waves near atmospheric pressure using a new H³⁵Cl spectroscopic laser diagnostic. The ability to monitor the isotope H³⁵Cl was possible using a laser source centered at 3045.06 cm^-1 aiming at the H³⁵Cl R(8) transition line in the fundamental band of the spectrum. A large span of temperatures was investigated, i.e. ranging from 1068 to 1444 K for CHCl₃ pyrolysis, where the most sensitive reaction CHCl₃ <span><math><mrow><mo>⇄</mo><mspace></mspace></mrow></math></span> CCl₂ + HCl (R1) produces the H³⁵Cl in correlation to the natural abundance proportions, namely <span><math><mrow><mrow><mo>[</mo><mrow><msup><mrow><mi>H</mi></mrow><mn>35</mn></msup><mi>C</mi><mi>l</mi></mrow><mo>]</mo></mrow><mo>≈</mo><mn>3</mn><mspace></mspace><mo>×</mo><mrow><mo>[</mo><mrow><msup><mrow><mi>H</mi></mrow><mn>37</mn></msup><mi>C</mi><mi>l</mi></mrow><mo>]</mo></mrow></mrow></math></span>. Similarly, the oxidation of CHCl₃/CH₄ was recorded at temperatures between 1471 and 2094 K, and the interactions of the active Cl radicals <img>provided by the dichlorocarbene (CCl₂) via the reaction 2CCl₂ <span><math><mrow><mo>⇄</mo><mspace></mspace></mrow></math></span> C₂Cl₃ + Cl (R2)<img> with CH₄ are observed and driven by the reaction CH₄ + Cl <span><math><mrow><mo>⇄</mo><mspace></mspace></mrow></math></span> CH₃ + HCl (R3). Numerical predictions from available detailed kinetics mechanisms for chlorinated hydrocarbons in the literature are compared against this comprehensive set of experimental results, and significant discrepancies are observed. Routes for improvements toward predicting this major intermediate species, i.e. HCl, are suggested. By strengthening the fundamental database for the combustion kinetics of chlorinated hydrocarbons, strategies to reduce the dominant release of extremely toxic chemicals could be discovered.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105823"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145018806","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":"Soot primary particle radial profiles in laminar diffusion flames for Jet A-1/SAF fuels: A SAXS study","authors":"M. Littin ,&nbsp;M. Mazur ,&nbsp;G. Lefevre ,&nbsp;M. Sztucki ,&nbsp;A. Fuentes ,&nbsp;J. Yon","doi":"10.1016/j.proci.2025.105852","DOIUrl":"10.1016/j.proci.2025.105852","url":null,"abstract":"<div><div>Sustainable aviation fuels (SAF) are designed to progressively replace conventional Jet A-1 fossil fuel, with documented lower soot emissions. However, detailed understanding of how SAF blending affects soot formation mechanisms remains limited. The present study employs Small-Angle X-ray Scattering (SAXS) to characterize soot primary spheres in laminar diffusion flames burning ethylene and Jet A-1/HEFA-SPK blends and to analyze their spatial distribution. Using a recently developed Spline-Based Abel Transform (SAT) method for signal deconvolution and an improved SAXS model, spatially-resolved radial profiles of primary particle size distributions are determined across the flame. The analysis reveals distinct differences between pure Jet A-1 and HEFA-SPK-blended flames: Jet A-1 produces larger primary particles (maximum <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>g</mi><mi>e</mi><mi>o</mi></mrow></msub></math></span> of <span><math><mrow><mn>27</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>5</mn><mspace></mspace><mi>nm</mi></mrow></math></span>) with sharp transitions between growth and oxidation regions, while HEFA-SPK blends show smaller particles (maximum <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>g</mi><mi>e</mi><mi>o</mi></mrow></msub></math></span> of <span><math><mrow><mn>16</mn><mo>±</mo><mn>2</mn><mo>.</mo><mn>5</mn><mspace></mspace><mi>nm</mi></mrow></math></span>) with more gradual transitions. This suggests that HEFA-SPK addition fundamentally alters soot formation dynamics rather than simply reducing particle size. The Porod invariant, which is proportional to the soot volume fraction, shows systematic decreases in soot volume fraction with increasing HEFA-SPK content while maintaining similar particle size distribution patterns. This work presents the first comprehensive dataset of spatially-resolved primary particle characteristics in aviation fuel flames, offering valuable insights for soot formation modeling and clean combustion technology development.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":""},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104443","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":"Influence of dispersion length on volume-averaged simulations of ammonia/air combustion in porous media burners","authors":"Rishabh Puri ,&nbsp;Daniel Kretzler ,&nbsp;Benjamin Bock-Seefeld ,&nbsp;Björn Stelzner ,&nbsp;Nora Brachhold ,&nbsp;Jana Hubálková ,&nbsp;Dimosthenis Trimis ,&nbsp;Christos Aneziris ,&nbsp;Oliver T. Stein ,&nbsp;Thorsten Zirwes","doi":"10.1016/j.proci.2025.105856","DOIUrl":"10.1016/j.proci.2025.105856","url":null,"abstract":"<div><div>Ammonia is a carbon-free alternative to fossil fuels and can potentially be integrated in the existing energy infrastructure. However, due to poor flame stability and high pollutant emissions, clean combustion of ammonia is a current topic of research. Porous media burners have shown potential to improve the combustion characteristics of ammonia and ammonia blends, which are otherwise difficult to stabilise in conventional burners. Combustion in porous media can be investigated in great detail by performing three-dimensional direct pore-level simulations (3D-DPLS). However, 3D-DPLS with complex ammonia chemistry are computationally expensive. Volume-averaged simulations (VAS) are an efficient alternative for numerical investigations of porous burners. In this work, a comprehensive VAS framework is proposed for 1D, 2D, and 3D transient VAS, taking variable porosity, detailed chemistry and diffusion into account. The numerical framework allows for on-the-fly definitions of constitutive models for effective properties, e.g. tortuosity, dispersion and permeability. After successful validation with other VAS cases from literature, the new code is used to analyse an experimentally investigated novel porous ammonia burner. The analysis is performed to study the effect of the characteristic dispersion length of the solid matrix, which is hard to measure for practical geometries, on pollutant formation and energy balance. All other effective properties are obtained directly from <span><math><mi>μ</mi></math></span>-CT scans. Both fuel-lean and fuel-rich conditions of ammonia/air combustion in porous media are investigated. As the characteristic dispersion length increases, local peak temperatures decrease. This significantly affects the predicted <figure><img></figure> and NH₃ emissions. Higher dispersion lengths lead to a broadening of the flame zone that can lead to larger lift-off heights from the burner inlet and merging of neighbouring flames Therefore, reliable estimates of characteristic dispersion lengths are required to achieve good predictions from VAS.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105856"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104444","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 the thermal decomposition reactions of HMX using online photoionization mass spectrometry","authors":"Hairong Ren ,&nbsp;Guangda Luo ,&nbsp;Xintong Xiao ,&nbsp;Yuzhou Huang ,&nbsp;Feng Zhang ,&nbsp;Long Zhao ,&nbsp;Zhongyue Zhou ,&nbsp;Xinghui Liu ,&nbsp;Xiang Guo ,&nbsp;Fei Qi","doi":"10.1016/j.proci.2025.105849","DOIUrl":"10.1016/j.proci.2025.105849","url":null,"abstract":"<div><div>1,3,5,7-Tetranitro-1,3,5,7-tetrazoctane (HMX) is a high-performance energetic material widely used in solid propellants. Understanding its thermal decomposition process is crucial for improving the combustion efficiency of these propellants. However, the rapid pyrolysis process and the complexity of the resulting products pose significant challenges to elucidating its decomposition mechanism. To investigate the pyrolysis process of HMX, online photoionization time-of-flight mass spectrometry (PI-TOFMS) and atmospheric photoionization ultra-high resolution mass spectrometry (APPI-HRMS) were employed to characterize the thermal decomposition products at atmospheric pressure (10⁵ Pa) and low pressure (10⁻³ Pa), respectively. Leveraging the soft ionization capability of photoionization, several key pyrolysis products of HMX were identified, such as HONO-elimination products, NO₂-elimination products, fragments from ring opening, and products from ring contraction and growth. The experimental results reveal that the thermal decomposition process of HMX involves several possible channels: (i) HONO-elimination &amp; N<img>NO₂ bond cleavage; (ii) cleavage of HMX along the symmetry axis into two INT148; (iii) ring contraction; (iv) ring scission; (v)growth of nitrogen-containing polycyclic aromatic hydrocarbons (NPAHs).</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105849"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104446","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":"Three-dimensional structure and burning speed of turbulent premixed H2–air and H2/CH4–air Bunsen flames using high-speed tomographic imaging","authors":"Tao Li ,&nbsp;Haowen Chen ,&nbsp;Simone Hochgreb","doi":"10.1016/j.proci.2025.105830","DOIUrl":"10.1016/j.proci.2025.105830","url":null,"abstract":"<div><div>The deployment of lean premixed hydrogen combustion for carbon-free power generation necessitates a better understanding of flame structure and burning speed, where volumetric information plays a crucial role. This work presents a novel tomographic imaging approach to reconstruct the volumetric Mie scattering signal distribution from seeded droplets in Bunsen flames, enabling detailed measurements of 3D flame surface topology, surface area, and turbulent flame speed. A series of lean turbulent premixed H₂-air and H₂/CH₄-air flames from the Cambridge piloted Bunsen burner were investigated, systematically varying the equivalence ratio, Lewis number, and Karlovitz number. A high-speed tomographic imaging system, consisting of eight simultaneous views was employed to capture volumetrically illuminated Mie scattering within an approximately 20(x)<span><math><mo>×</mo></math></span>40(y)<span><math><mo>×</mo></math></span>12(z)<!--> <!-->mm<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span> probe volume. The reconstructed 3D signals using the SMART algorithm enables reliable flame front detection and surface triangulation. Based on this reconstruction, flame structures were analyzed by computing mean and Gaussian curvatures, as well as principal curvatures. Results reveal that hydrodynamic instabilities (HDI) induce regular surface oscillations near the Burner exist, while thermodiffusive instabilities (TDI) enhance surface fluctuations near the flame tip. The HDI is found to be more prominent at low-<span><math><mrow><mi>K</mi><mi>a</mi></mrow></math></span> and near-unity <span><math><mrow><mi>L</mi><mi>e</mi></mrow></math></span> conditions, whereas TDI dominates in moderate-<span><math><mrow><mi>K</mi><mi>a</mi></mrow></math></span> and sub-unity <span><math><mrow><mi>L</mi><mi>e</mi></mrow></math></span> flames, leading to increased surface wrinkling. Additionally, both instantaneous flame surfaces and surfaces based on the mean progress variable were examined and used to derive global and local flame speeds. It was observed that the normalized turbulent flame speed ratio, <span><math><mrow><msub><mrow><mi>S</mi></mrow><mrow><mtext>T</mtext></mrow></msub><mo>/</mo><msub><mrow><mi>S</mi></mrow><mrow><mtext>L</mtext></mrow></msub></mrow></math></span>, can be effectively scaled with turbulence intensity and Lewis number. However, the accuracy of the surface area calculation significantly affects the precise determination of <span><math><mrow><msub><mrow><mi>S</mi></mrow><mrow><mtext>T</mtext></mrow></msub><mo>/</mo><msub><mrow><mi>S</mi></mrow><mrow><mtext>L</mtext></mrow></msub></mrow></math></span>. Overall, the tomographic laser diagnostic technique demonstrated in this study provides valuable insights into the flame structures and burning characteristics of lean turbulent premixed H₂-air and H₂/CH₄-air combustion.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105830"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104550","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":"Numerical analysis of the stability of iron dust Bunsen flames","authors":"T. Hazenberg,&nbsp;D. Braig,&nbsp;J. Mich,&nbsp;A. Scholtissek,&nbsp;C. Hasse","doi":"10.1016/j.proci.2025.105861","DOIUrl":"10.1016/j.proci.2025.105861","url":null,"abstract":"<div><div>This article presents numerical simulations of the response of an iron dust Bunsen flame to abrupt changes in particle seeding. A validated numerical model is employed to investigate the effect of particle seeding fluctuations on flame stability. Simulations are conducted for the Bunsen setup in both right-side-up and upside-down configurations. No significant differences in flame response are identified in flame stability between the right-side-up and upside-down configurations. The flame response does not show signs of flame wrinkling or activation of other intrinsic instabilities. As a result, the flame is surprisingly robust to abrupt changes in particle loading. We hypothesize that the robustness of the flame to imposed fluctuations is due to the lack of a feedback mechanism between the burned temperature and the heat release rate. This mechanism is present in conventional, chemistry-driven, gaseous flames. However, such a mechanism is absent in iron dust flames because the combustion of individual iron particles is limited by oxygen diffusion, which is insensitive to temperature. The high robustness of the flame appears to contradict experimental observations, where flames are found to be highly unstable, which raises questions about the mechanism underlying the instability of experimental flames.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105861"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154429","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":"Numerical characterization of stratified weakly turbulent hydrogen flames","authors":"Raphael Strickling,&nbsp;Faizan Habib Vance,&nbsp;T. Jeremy P. Karpowski,&nbsp;Christian Hasse,&nbsp;Arne Scholtissek","doi":"10.1016/j.proci.2025.105844","DOIUrl":"10.1016/j.proci.2025.105844","url":null,"abstract":"<div><div>Lean hydrogen combustion offers great potential to reduce greenhouse gas emissions. However, due to its unique combustion characteristics, hydrogen poses significant challenges regarding operational safety of burners and their <figure><img></figure> emissions. To address these challenges, burner designs must be adapted to ensure the safe and efficient combustion of hydrogen. Previous works indicate that a targeted mixture stratification in the radial direction has the potential of reducing the flashback propensity of hydrogen flames anchored at the sharp edge of a burner outlet. However, the homogeneity of the mixture at the burner outlet also has a significant impact on <figure><img></figure> emissions of (partially) premixed hydrogen-air flames. Combining both ideas, two burner designs featuring a <em>radial</em> mixture stratification with varying levels of mixture homogeneity in the <em>angular</em> direction at the burner outlet are presented. These designs are analyzed using LES with adaptive mesh refinement for the flame zone and detailed chemistry to evaluate the flame’s stabilization behavior and <figure><img></figure> emissions in comparison to a reference fully premixed flame. The results of the numerical simulations suggest that the mixture stratification approach is effective for the weakly turbulent flames stabilized on the mesoscale nozzles considered in the present work. Furthermore, the analysis of the <figure><img></figure> emissions provides useful implications to guide future nozzle design and assessment prior to (additive) manufacturing and experimental investigation.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105844"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154693","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}