Proceedings of the Combustion Institute最新文献

{"title":"Semi-empirical lumped models of polymer pyrolysis for poly(methyl methacrylate) and polyoxymethylene","authors":"Tim J. Mallo,&nbsp;Adam Dumas,&nbsp;Phillip R. Westmoreland","doi":"10.1016/j.proci.2025.105807","DOIUrl":"10.1016/j.proci.2025.105807","url":null,"abstract":"<div><div>Quantitative lumped-kinetics models are constructed for pyrolysis of poly(methyl methacrylate) (PMMA) and polyoxymethylene (POM) by using known reaction classes to describe mass loss (volatiles loss) by purely 1st-order decomposition rates, averting the need for molar- or number-based concentrations. These semi-empirical models will aid in establishing fundamental kinetics of polymer decomposition for solid rocket fuels and thermal recycling. Simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA-DSC) are applied to measure mass-loss and heat-consumption rates and the influences of heating rate, sample size, and end groups as a basis for modeling. This combination of rate data and products is useful for proposing pathways and establishing mechanisms. PMMA and POM homopolymers were selected for base-case pyrolysis studies due to their relatively simple structures and their tendencies to yield primarily monomer. For comparison, kinetics was also measured for POM copolymer, where -CH₂CH₂O- units are interspersed among the -CH₂O- units.</div><div>Two-, three-, and four-lumped-reaction parameterized models are presented for pyrolysis rates and yields from POM homopolymer, POM copolymer, and PMMA, respectively. The lumped reactions correspond to temperature regions that are dominated by a single type of first-order reaction, each with a mass fractional yield of volatiles, an Arrhenius pre-exponential factor, and an activation energy. The first, lowest-temperature lump may be pericyclic reactions to molecular intermediates, or the main chain or weakly bound end groups or side groups may homolytically scission. Polymer-radical fragments could be trapped by recombination and be too large to be volatile. If enough polymeric radicals are formed, beta-scission into monomers can be rate-limiting for volatiles formation, and at higher temperatures, homolytic scission would be rate-limiting. At highest temperatures, stages can be rate-limited by internal H-abstraction or termination via exothermic reactions to make strongly bound char residues.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105807"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830202","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":"Analysis of thermodiffusive instabilities and flame front wrinkling in a hydrogen-fueled engine","authors":"Pedro Ye,&nbsp;Jannick Erhard,&nbsp;Cooper Welch,&nbsp;Hao Shi,&nbsp;Andreas Dreizler,&nbsp;Benjamin Böhm","doi":"10.1016/j.proci.2025.105884","DOIUrl":"10.1016/j.proci.2025.105884","url":null,"abstract":"<div><div>This study investigates the interplay between thermodiffusive instabilities (TDI) and flame front wrinkling in a hydrogen-fueled internal combustion engine (ICE). High-speed planar laser-induced fluorescence (LIF) of the SO₂ tracer was employed to visualize flames in an optically accessible, spark-ignited ICE operating under a lean H₂ mixture at 400<!--> <!-->rpm and 800<!--> <!-->rpm. The results reveal that TDI cells are distinctly more pronounced at 400<!--> <!-->rpm and in slower flames, while at 800<!--> <!-->rpm, increased turbulence suppresses cell development and enhances overall flame wrinkling. A negative correlation between these two features indicates that TDI cells flourish in less disturbed conditions, whereas turbulence-driven wrinkling disrupts their formation. These findings suggest that at higher, more realistic engine speeds, TDI cell formation is significantly mitigated. However, other instability-driven effects, such as localized heat release variations, wall heat transfer, and flame quenching, may still play a crucial role in H₂ engine combustion. Understanding these interactions is essential for accurately modeling and optimizing hydrogen-fueled ICEs.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105884"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216307","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 priori analysis of multi-dimensional flamelet effects in a transcritical LOX/GH2 jet flame","authors":"Hanzhang Cao,&nbsp;Wang Han,&nbsp;Yihao Tang,&nbsp;Lijun Yang","doi":"10.1016/j.proci.2025.105864","DOIUrl":"10.1016/j.proci.2025.105864","url":null,"abstract":"<div><div>Accurate modeling of transcritical combustion is of critical importance for the development of high-efficiency rocket engines. While the one-dimensional flamelet theory has been extensively used in transcritical and supercritical combustion simulations, a comprehensive analysis of multi-dimensional flamelet effects remains scarce. To this end, <em>a priori</em> analysis of multi-dimensional flamelet effects in a transcritical LOX/GH2 jet flame is performed in this work by comparing 1D flamelet solutions with multi-dimensional flamelets extracted from DNS solutions. The results show that while conventional 1D flamelet solutions can provide a good approximation of the jet flame structure, incorporating differential diffusion helps to accurately predict the flame front position. Furthermore, asymptotic scaling analysis and budget analysis of generalized flamelet equations are conducted for the extracted flamelets. It is found that multi-dimensional flamelet effects do have a substantial impact on the jet flame. Nevertheless, flame-normal diffusion is dominant over flame-tangential diffusion. These findings suggest that the 1D flamelet assumption is reasonable for the transcritical LOX/GH2 jet flame and that attention should be paid to incorporating differential diffusion effects in the modeling of transcritical LOX/GH2 jet flames.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105864"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216399","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":"Super-resolution reconstruction of scalar fields from the pyrolysis of pulverised biomass using deep learning","authors":"A. Shamooni ,&nbsp;R. Cheng ,&nbsp;T. Zirwes ,&nbsp;O.T. Stein ,&nbsp;A. Kronenburg","doi":"10.1016/j.proci.2025.105982","DOIUrl":"10.1016/j.proci.2025.105982","url":null,"abstract":"<div><div>Recently, advanced deep-learning techniques have been successfully applied as deconvolution operators to super-resolve the low-resolution data in large-eddy simulation (LES). The super-resolution (SR) operator provides an approximate inverse to the filter operators in LES such that the under-resolved and un-resolved sub-grid information can be reconstructed from the resolved scales. In this work, a particle-aware attention-based conditional super-resolution generative adversarial network (PACASRGAN) is proposed for the fourfold SR of gas field scalars which are generated by the pyrolysis process in a hot turbulent flow laden with pulverised biomass particles. Multiple carrier-phase direct numerical simulations (DNS) of two-way coupled particle-laden flows with heat and mass transfer, that mimic the near-burner field of pulverised biomass combustion (PBC) systems, are carried out to build the training/testing datasets. The model performance is assessed in an <em>a priori</em> manner by investigating statistical quantities of interest for the modelling in LES of PBC. The results show that the proposed model can super-resolve the temperature and mixture fraction fields to a good accuracy and outperforms unconditional GAN models. Particles create localised sources/sinks via two-way coupling which sharpen scalar gradients in the subgrid. The particle mask and feature vector encode this localisation to improve the predictions of the generator. The scalar spectra, the conditional average of unresolved scalar variances, the probability density function (PDF), and the conditional average of the square of the mixture fraction gradient from the reconstructed fields follow the DNS values well. Slight deviations are observed at rich conditions in conditional statistics and at the tail of the PDFs. Nonetheless, the results demonstrate that SR is applicable to two-way coupled particle-laden flows with heat and mass transfer, providing reasonably accurate high-resolution information for both the entire gas field and particle positions.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105982"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145516526","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":"Hydrogen fluoride emissions from lithium-ion batteries during induced thermal runaway via in situ laser spectroscopy","authors":"Yi Yan,&nbsp;Nicolas S.B. Jaeger,&nbsp;R. Mitchell Spearrin","doi":"10.1016/j.proci.2025.105800","DOIUrl":"10.1016/j.proci.2025.105800","url":null,"abstract":"<div><div>Improved understanding of hydrogen fluoride (HF) emissions from lithium-ion battery fires, including the temporal dynamics, is needed to optimize fire response and protection. Due to the high polarity of HF and its associated surface adsorption and reactivity, most traditional sensing methods are prone to error and slow response due to issues with sampling or surface interactions. To address these limitations, an in situ tunable diode laser absorption spectrometer is developed to achieve real-time measurements of HF emissions during dynamic battery fires with a temporal resolution of milliseconds, and with detection limits of single parts per million along with several orders of magnitude of dynamic range. The laser spectrometer is used in situ to perform measurements near the fire source so that the fire dynamics and the transient behavior of HF emissions can be more accurately characterized. Thermal runaway and fire/explosion conditions of model 18650 lithium-ion batteries are simulated in a conical radiative heater, and HF measurements are performed online via an optical access port in the effluent exhaust. By varying the radiative heating flux of the conical heater and the initial state of charge of the batteries, different characteristics of the safety venting and thermal runaway behavior of lithium-ion batteries and the corresponding emissions of toxic HF gas are measured. These findings provide valuable insights into the dynamics of lithium-ion battery fires and will aid in the development of strategies to mitigate their associated risks.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105800"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144860419","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":"Single-step flame synthesis of surface-disordered titania nanoparticles in Hencken-supported hydrogen premixed flames","authors":"Hu Meng ,&nbsp;Yuhao Nie ,&nbsp;Junqing Chen ,&nbsp;Yun Huang ,&nbsp;Yihua Ren","doi":"10.1016/j.proci.2025.105944","DOIUrl":"10.1016/j.proci.2025.105944","url":null,"abstract":"<div><div>Surface-disordered TiO₂ nanoparticles exhibiting various colors including grey, yellow, blue, and black have attracted considerable attention owing to their outstanding photocatalytic activity, attributed to their narrow bandgap and thus enhanced absorption of solar energy. In this study, we have successfully synthesized TiO₂ nanoparticles with tailored surface-disorder structures using a well-controlled H₂/O₂/N₂ premixed Bunsen flame supported by multi-element diffusion flames in a single step. To systematically examine the influence of gas composition on surface-disorder layer formation, we designed four distinct flame conditions maintaining consistent flame structures, adiabatic temperatures, and precursor concentrations while varying the atmospheric composition. <em>In-situ</em> OH-planar laser induced fluorescence (PLIF), spontaneous Raman scattering (SRS), and 2D phase-selective laser-induced breakdown spectroscopy (PS-LIBS) has been employed to characterize the flame structures, temperature profiles, atmospheric conditions, and particle volume fraction across all flame conditions. The <em>in-situ</em> diagnostic results verify that the designed flame conditions have identical particle formation and growth route in flames but with varying gas-particle interactions under different post-flame atmospheres. <em>Ex-situ</em> characterization through high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) of the synthesized nanoparticles demonstrates that TiO₂ nanoparticles with surface disorder structure and rutile phase are more preferentially formed under reducing atmospheric condition. Furthermore, both <em>ex-situ</em> UV-Vis spectra and <em>in-situ</em> PS-LIBS indicated that a higher H₂ mole fraction in the post-flame region can enhance the light absorption of the synthesized nanoparticles attributed their stronger surface disorder structures.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105944"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145319675","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 hot-spot-induced pre-ignition in methanol- and hydrogen-fueled spark-ignition engines","authors":"D. Golc ,&nbsp;S. Esposito ,&nbsp;M. Khosravi ,&nbsp;J. Beeckmann ,&nbsp;H. Pitsch","doi":"10.1016/j.proci.2025.105932","DOIUrl":"10.1016/j.proci.2025.105932","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The transition of the transport sector towards more sustainable propulsion requires the adoption of alternative fuels. Methanol and hydrogen are promising options because of their possible renewable production pathways, low to zero carbon content, low pollutant emission, and potential for reaching higher thermal efficiencies. A drawback is that hydrogen and methanol are more prone to hot-spot-induced pre-ignition (PI) due to their lower minimum ignition energy compared to conventional fuels. Hot-spot-induced PI can occur in engines due to hot surfaces acting as ignition points, which is a limiting factor for operation, safety and efficiency. Although undesirable in spark ignition engines (SI), hot-spot-induced ignition can facilitate the use of low-cetane fuels such as methanol and hydrogen in compression ignition engines (CI). Understanding the effects leading to hot-spot-induced pre-ignition is essential for both suppressing the phenomenon in SI engines and leveraging it in CI engines. This study investigates hot-spot-induced PI phenomena using an SI single-cylinder research engine featuring a prototype glow-plug equipped with an integrated thermocouple in order to create a controlled hot spot inside the combustion chamber. Methanol has been introduced in the combustion chamber with a direct injection (DI), while hydrogen with a port fuel injector (PFI). A parametric study was conducted using methanol and hydrogen to identify dependencies of PI events linked to certain engine operating parameters. A comprehensive data analysis featuring 3D Reynolds averaged Navier Stokes (RANS) and chemical kinetics simulations were conducted to explain the main mechanisms responsible for PI. Generally, hydrogen requires a higher hot-spot temperature to achieve pre-ignition compared to methanol. For methanol, this study provides insights into the dependencies of various parameters on the ignition timing in CI applications, allowing potentially to achieve a controllable CI combustion with glow-plug assistance. An important finding is that while methanol combustion can be effectively controlled through glow-plug temperature, the study demonstrates that such controllability is more challenging for hydrogen. Indeed, numerous parameters influencing hot-spot-induced ignition were identified. In particular, the local mixture composition near the glow-plug and elevated pressures were found to significantly impact the onset of PI, with higher pressures effectively suppressing pre-ignition. This counterintuitive behavior is explained by the inverse pressure dependence of ignition delay times for hydrogen and analyzed with reaction pathway analysis. Overall, it was observed that by adjusting the operating parameters, the potential hot-spot temperature required to trigger PI could be optimized, allowing for an increase of up to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mtext&gt;100&lt;/mtext&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mtext&gt;K&lt;/mtext&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. These insights are essential for developing s","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105932"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412614","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 theoretical study of 1-propanol H-abstractions and successive reactivity","authors":"Sarah N. Elliott ,&nbsp;Maristella Di Teodoro ,&nbsp;Simone Vari ,&nbsp;Luna Pratali Maffei ,&nbsp;Zeynep Serinyel ,&nbsp;Océane Clement ,&nbsp;Claire Grégoire ,&nbsp;Eric L. Petersen ,&nbsp;Olivier Mathieu ,&nbsp;Guillaume Dayma ,&nbsp;Carlo Cavallotti","doi":"10.1016/j.proci.2025.105928","DOIUrl":"10.1016/j.proci.2025.105928","url":null,"abstract":"<div><div>A mechanistic understanding of alcohol pyrolysis and oxidation is critical to their effective integration into the fuel industry. 1-propanol (1-C₃H₇OH) is a promising biofuel and, moreover, its mechanism is a foundation for that of larger alcohols. As part of a combined modeling-experimental-theoretical investigation into 1-C₃H₇OH, we explore the H abstractions from 1-C₃H₇OH with ab initio transition state theory-based master equation (AI-TST-ME) evaluations for the two abstractors, OH and H, that are influential during 1-C₃H₇OH combustion. We report branching fractions between the resulting C₃H₇O radicals (i.e., at 1500 K, for the OH abstractor: 0.40, 0.27, 0.24, and 0.09 to α-, β−, γ−, and ο−C₃H₇O; for the H abstractor: 0.80, 0.14, 0.06, and 0.00). The sensitivity to level of theory as well as the influence of multidimensional torsional effects are evaluated for the abstractions by OH. Notably, the correction for torsional coupling for the α−C₃H₇O is about half of that as for the β−C₃H₇O – fully neglecting the multidimensional effect, then, would lead to significantly different branching fractions. The subsequent dissociation of the C₃H₇O radicals to nine products, including CH₃, OH, ethene, ethyl radical, and H is also reported with AI-TST-ME computations. We find, however, that at relevant temperatures and pressures, very little 1-C₃H₇OH + OH collisionally stabilizes to thermalized C₃H₇O radicals (i.e., 7 % at 1 atm and 1500 K). Instead, the abundant, rovibrationally excited populations of C₃H₇O radicals promptly dissociate to the products. In the first exploration of the influence of non-thermal effects on the branching fractions to dissociation products, we find that H production enhances significantly (i.e., more than a factor of 2) at the cost of OH production.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105928"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145412611","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":"Full-spectrum fitting method applied to YAG:Dy : Impact of oxygen content and laser fluence on wall-temperature phosphor thermometry for combustion","authors":"Tobias Guivarch ,&nbsp;Hugo Samson ,&nbsp;Jérôme Bonnety ,&nbsp;Jessy Elias ,&nbsp;Sébastien Ducruix ,&nbsp;Clément Mirat ,&nbsp;Christopher Betrancourt ,&nbsp;Guilhem Dezanneau ,&nbsp;Ronan Vicquelin","doi":"10.1016/j.proci.2025.105845","DOIUrl":"10.1016/j.proci.2025.105845","url":null,"abstract":"<div><div>Achieving the European net-zero greenhouse gas emissions target requires the development of sustainable combustion processes across various industrial sectors. These promising alternatives introduce new challenges, such as modifying wall heat transfer. Accurate surface temperature measurements are essential for understanding these effects. Laser-Induced Phosphorescence (LIP) provides a semi-invasive method that exploits the temperature-dependent phosphorescence spectra of thermographic phosphors. YAG:Dy is a thermographic phosphor that emits a phosphorescence signal over the range of 300 K to 2000 K. However, its poor sensitivity with the intensity ratio method and its low sensitivity at lower temperatures with the lifetime method limit its use to high-temperature combustion applications. Additionally, its sensitivity to ambient oxygen reduces the accuracy of those methods. This study evaluates the performance of the Full-Spectrum Fitting (FSF) method, developed by the EM2C Laboratory in Lechner et al. (2022), when applied to YAG:Dy. The method leverages the phosphor’s spectral temperature dependence over a wide range (303 to 1773 K), achieving an accuracy of 0.3 K and a precision of 8.4 K under given experimental conditions. It is observed that there is a laser fluence threshold above which temperature determination using the FSF method becomes independent of laser fluence. The impact of YAG:Dy’s sensitivity to oxygen concentration on temperature measurement is quantified. In the worst case, uncertainty in oxygen concentration can introduce a temperature error ranging from 7 to 19 K. Guidelines are provided to help mitigate these sensitivities in combustion applications.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105845"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154442","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":"Turbulence-flame interactions in high-Karlovitz-number lean premixed hydrogen piloted jet flames","authors":"G.S. Russell ,&nbsp;T.L. Howarth ,&nbsp;A.W. Skiba ,&nbsp;C.D. Carter ,&nbsp;A.J. Aspden","doi":"10.1016/j.proci.2025.105868","DOIUrl":"10.1016/j.proci.2025.105868","url":null,"abstract":"<div><div>Turbulence is known to exaggerate the thermodiffusive response in lean premixed hydrogen flames. The mean local flame speed has been demonstrated to increase with Karlovitz number, but the range of validity has not been established; furthermore, several studies observed a decrease in turbulent/local flame speed at moderately-high Karlovitz numbers. All of the aforementioned DNS studies were conducted in the canonical flame-in-a-box (FIAB) configuration. To investigate these observations further and to establish whether similar behaviour is observed in realistic configurations, six DNS have been conducted to reproduce a laboratory piloted jet flame. The jet internal diameter was 7.04<!--> <!-->mm, with bulk inflow velocities from 6<!--> <!-->m/s to 192<!--> <!-->m/s (increasing in factors of 2), corresponding to jet Reynolds numbers of 2,500 to 80,000; the reactants had an equivalence ratio of <span><math><mi>φ</mi></math></span> <!--> <span><math><mo>=</mo></math></span> <!--> <!-->0.32 at atmospheric conditions. Complementary turbulent FIAB simulations are used to compare the realistic configuration with the canonical abstraction. The mean local flame speed is found to peak in the 48<!--> <!-->m/s case, after which a decrease is observed; the transition is found to occur at slightly higher Karlovitz number in the FIAB configuration. A key difference between the two configurations is shown to be that the jet flames are effectively unconfined, whereas the turbulent FIAB area confined by the periodic boundary conditions (so there is a limit on how much flame surface area can be generated in a given volume). Finally, at the highest inflow speed, the jet flame appears to become lifted (there is a significant region near the inlet with little-to-no heat release), and turbulence-flame interaction is shown to be distinctly different to that at lower Karlovitz numbers; the thermodiffusive response is suppressed without the flame becoming fully distributed.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105868"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262369","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}