Proceedings of the Combustion Institute最新文献

{"title":"Ignition dynamics of a hydrogen-fueled annular combustor","authors":"Nicolas Vaysse,&nbsp;Daniel Durox,&nbsp;Ronan Vicquelin,&nbsp;Sébastien Candel,&nbsp;Antoine Renaud","doi":"10.1016/j.proci.2025.105893","DOIUrl":"10.1016/j.proci.2025.105893","url":null,"abstract":"<div><div>Hydrogen is currently considered as a possible fuel substitute for gas turbines and aeroengines in the context of decarbonizing transportation and energy industries. However, its combustion raises scientific challenges due to its broad flammability domain and propensity to combustion instabilities. To ensure safe operation of hydrogen fueled systems, it is mandatory to study hydrogen combustion in industrially-relevant annular configurations that are typically found in applications. The present investigation is carried out in the MICCA facility equipped with 16 hydrogen injection units. In each injector, hydrogen is delivered in cross-flow in a swirled air flow. The aim of this investigation is to study the light-round ignition dynamics of a hydrogen-fueled annular combustor. The ignition sequence is observed with a high-speed camera equipped with an OH<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span> filter. The light-round delays are determined for a range of injection velocities and for equivalence ratios between 0.29 to 0.72. The relatively short light-round delays (from 18 ms to 35 ms), are considerably lower than those found for hydrocarbon flames. It is also found that at low equivalence ratios, the light-round proceeds but does not establish all the flames. The light-round delay is shown to decrease when the equivalence ratio is increased, and also when the inlet velocity is augmented at constant equivalence ratio. A link is made between the average flame displacement velocity and the turbulent burning velocity taking into account the thermal expansion. It is found that this can be achieved with a model combining two expressions for the turbulent burning velocity, corresponding to high and low values of the laminar burning velocity. The model captures the influence of injection velocity and equivalence ratio on the flame displacement velocity during light round. It is thus possible to derive a correlation for the reduced light-round delay that suitably retrieves experimental data.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105893"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145319801","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 soot oxidation reaction time scale on soot break-through","authors":"Gandolfo Scialabba ,&nbsp;Antonio Attili ,&nbsp;Heinz Pitsch","doi":"10.1016/j.proci.2025.105930","DOIUrl":"10.1016/j.proci.2025.105930","url":null,"abstract":"<div><div>A previous Direct Numerical Simulation (DNS) study is extended to assess the influence of the soot oxidation reaction time scale on soot break-through in turbulent non-premixed flames. In such cases, soot is formed in rich regions and then pushed toward the flame, where it is often completely oxidized without escaping to the lean region and hence the environment. However, a fast relative drift of soot particles with respect to the oxidation layer paired with local flame extinction can lead to soot break-through (soot leakage), even when the total equivalence ratio is lean. These conditions are met when turbulence levels are sufficiently high, leading to a smoking flame behavior. The baseline configuration consists of a turbulent non-premixed temporal jet where significant soot break-through is observed due to local extinction and mixing. A soot oxidation Damköhler number is defined as the ratio of the flow and soot oxidation reaction time scales. A parametric variation of the soot oxidation Damköhler number is performed by varying the oxidation time scale, i.e., rescaling the soot oxidation rate coefficients, while keeping the flow time scale constant. The relative influence on soot break-through of OH and O₂-based soot oxidation reaction time scales at varying soot oxidation Damköhler numbers (<span><math><msub><mrow><mi>Da</mi></mrow><mrow><mi>Ox,OH</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>Da</mi></mrow><mrow><mi>Ox</mi><mo>,</mo><msub><mrow><mi>O</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></msub></math></span>) is quantified. Soot and gas-phase statistics are collected along Lagrangian trajectories to evaluate the relative impact of partial soot oxidation events. A modest change in peak soot mass is observed for both variations. An even smaller impact is found for soot mass break-through, which is only marginally affected by the soot oxidation reaction time scales, as it mainly occurs in regions with strong local extinctions. The results imply that, to capture soot break-through events in reduced-order models, an accurate description of local flame extinction is likely more important than the values of soot oxidation reaction rates.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105930"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145319800","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":"Clustering-based data-driven multi-fidelity reduced order modeling of ammonia combustion","authors":"Aysu Özden ,&nbsp;Riccardo Malpica Galassi ,&nbsp;Francesco Contino ,&nbsp;Alessandro Parente","doi":"10.1016/j.proci.2025.105881","DOIUrl":"10.1016/j.proci.2025.105881","url":null,"abstract":"<div><div>This study presents a multi-fidelity reduced-order modeling (MF-ROM) framework that uses unsupervised clustering to identify and separately model distinct combustion regimes within the training data. This regime-specific approach allows enhancing computational efficiency while maintaining high predictive accuracy. The proposed MF-ROM framework leverages Proper Orthogonal Decomposition (POD) for dimensionality reduction, manifold alignment for optimal data fusion, and Co-Kriging regression to incorporate both high-fidelity (HiFi) and low-fidelity (LoFi) datasets effectively. First, global clustering is applied to segment the design space into combustion regimes, significantly improving MF-ROM accuracy while reducing the number of required HiFi simulations. Additionally, localized clustering is explored within specific subsets of the design space, demonstrating further refinement in predictive performance. Ammonia combustion is selected as the benchmark case because it is carbon-free and a promising candidate for the energy transition. Moreover, its chemical characteristics make it particularly suitable for the clustering-based MF-ROM approach, as they facilitate the generation of a very diverse training dataset. Results show that the clustering-based MF-ROM achieves the same accuracy as the model without clustering with significantly fewer HiFi simulations, leading to a sixfold reduction in computational cost while maintaining predictive reliability. Moreover, local clustering enhances interpolation capabilities, particularly in regions where combustion characteristics exhibit strong variability. A comparative analysis of temperature and NO emissions confirms that the clustering-driven approach improves both accuracy and efficiency, which can lead to an increase in prediction accuracy up to 50%. The methodology offers a scalable and adaptable approach for optimizing MF-ROMs in reacting flows, supporting the development of low-emission combustion technologies.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105881"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262471","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":"Detonation chemistry and propagation characteristics in partially cracked ammonia","authors":"Jie Sun ,&nbsp;Salim M. Shaik ,&nbsp;Van Bo Nguyen ,&nbsp;Huangwei Zhang","doi":"10.1016/j.proci.2025.105910","DOIUrl":"10.1016/j.proci.2025.105910","url":null,"abstract":"<div><div>Ammonia has relatively low reactivity, making it difficult to initiate and maintain a stable detonation wave. Cracking ammonia into hydrogen and nitrogen can enhance the detonability of the mixture. This study evaluates the influence of ammonia cracking ratio (<em>κ</em>) on the detonation characteristics of partially cracked ammonia and oxygen mixtures (NH₃/H₂/O₂/N₂) by numerical simulations considering detailed chemistry. It aims to explain how the initial hydrogen generated from ammonia cracking affects the detonation. First, steady ZND structures and reaction flux paths are analyzed for different <em>κ</em>. The results show that NH₃ is primarily consumed via pyrolysis. The initial hydrogen reacts through reactions R3 (O+H₂→OH+H), R4 (OH+H₂→H+H₂O) and R160 (NH₃+H→NH₂+H₂), which releases heat and shortens the induction time. As <em>κ</em> increases, R3 and R4 replace R160 to dominate the initial hydrogen consumption. Besides, increasing <em>κ</em> also favors the pyrolysis of NH₃ by NH₃→NH₂→NH due to more H and OH radicals generated from the initial hydrogen reactions. Subsequently, unsteady pulsating and cellular detonations are simulated. Detonation waves propagate more stably as <em>κ</em> increases. Two re-initiation modes are identified for pulsating detonations. When <em>κ</em> is small, unburned mixture pockets are observed behind the leading shock. The mixtures within the pockets burn, creating pressure waves to interact with the leading shock. The interactions induce new reaction fronts to re-initiate the detonation. As κ increases, the reactivity of the shocked mixture increases, reshaping the reactivity gradient and causing the re-initiation mode to transition to the acceleration of the original reaction front. For cellular detonation, similar unburned gas pockets caused by the decoupling of transverse detonation waves are also observed. As κ increases, more initial hydrogen reacts and enhances the mixture reactivity behind the incident shock waves, leading to transverse detonation waves to propagate without decoupling. Hence the detonation waves become more stable.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105910"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation of turbulent premixed H2-jet flames at high exhaust gas recirculation","authors":"Maurus Bauer ,&nbsp;Björn Stelzner ,&nbsp;Peter Habisreuther ,&nbsp;Michael Schneider ,&nbsp;Christof Weis ,&nbsp;Dimosthenis Trimis","doi":"10.1016/j.proci.2025.105866","DOIUrl":"10.1016/j.proci.2025.105866","url":null,"abstract":"<div><div>This study presents an experimental investigation of a turbulent premixed hydrogen jet flame operating under high exhaust gas recirculation (EGR) rates. Experiments were conducted at a Reynolds number of 10<!--> <!-->000, exploring flames ranging from pure H₂–air mixtures to cases with an EGR rate of 0.67. The flames were carefully adjusted to maintain similar laminar burning velocities, enabling consistent comparisons and revealing a systematic increase in the equivalence ratio (<span><math><mi>Φ</mi></math></span>) with higher EGR rates. These operating conditions were derived through a detailed 1D analysis of H₂–air–EGR laminar flames using comprehensive chemical kinetics, complemented with measurements of the laminar burning velocities of premixed H₂–air–EGR flames. The flow field of the model burner setup and nozzle design was characterized under both non-reactive and reactive conditions using particle image velocimetry (PIV). OH* chemiluminescence imaging did not reveal significant changes in the overall structure of the flame, even as the equivalence ratio varied from <span><math><mi>Φ</mi></math></span> = 0.4 (pure H₂–air flame) to near-stoichiometric conditions (<span><math><mi>Φ</mi></math></span> = 0.77). Selected cases were further investigated using OH planar laser-induced fluorescence (OH-LIF), offering detailed visualization of the flame structure and corroborating the observations from OH* chemiluminescence. NO_X emissions remained low across all investigated EGR rates, demonstrating robust emission control. These findings enhance the understanding of hydrogen combustion dynamics under high EGR conditions and provide valuable insights for developing low-emission, high-stability combustion strategies.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105866"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262475","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":"Exhaust emissions point measurements on the secondary stage of an NH3-RRQL system","authors":"Cristian D. Avila Jimenez ,&nbsp;Renee Cole ,&nbsp;Jamie Parnell ,&nbsp;Mark Peckham ,&nbsp;David Wu ,&nbsp;Benjamin Emerson","doi":"10.1016/j.proci.2025.105791","DOIUrl":"10.1016/j.proci.2025.105791","url":null,"abstract":"<div><div>The Rich-Relaxation-Quench-Lean (RRQL) combustion system was recently proposed to increase combustion efficiency in ammonia (NH₃)-fueled gas turbines while reducing nitrogen oxides (NO_x). Success requires precise control of the lean secondary stage, where air oxidizes the remaining fuel from the rich primary stage. However, understanding pollutants distribution across the secondary stage is crucial for designing RRQL systems that minimize NO_x and nitrous oxide (N₂O) emissions. This study experimentally investigates axial and radial distributions of exhaust species across the secondary stage of a lab-scale NH₃-fueled RRQL burner. The burner operated with rich premixed NH₃–air mixtures and employed a secondary air injection geometry of five-4.1 mm diameter holes, selected for its ability to stabilize diffusion-like flames at <em>ϕ_global</em> = 0.85 and premixed-like flames at <em>ϕ_global</em> = 0.60. A fused quartz probe enabled gas sampling at multiple locations upstream within, and downstream from the secondary injection plane. At <em>ϕ_primary</em> = 1.13, results show that NO is formed slightly upstream the air injection plane, whereas NO₂ is rapidly produced downstream and NH₃ and N₂O slip through the walls between the jets. A notable fraction of total NOₓ was found to be NO₂, post-secondary combustion zone, underscoring the need to consider NO₂ explicitly in overall emissions assessments of staged NH₃ combustion systems. Decreasing <em>ϕ_global</em> to 0.60 reduces the overall emissions, highlighting the importance of premixed-like combustion in pollutants mitigation in the secondary stage. Although similar trends were observed at <em>ϕ_primary</em> = 1.15, higher NO_x levels resulted from increased NH₃ availability. However, thermal insulation of the combustor walls effectively reduced NH₃ slip, likely due to enhanced non-oxidative cracking, enabling sub-10 ppm N₂O emissions. These findings emphasize the importance of simultaneous primary and secondary stage tuning, reduction of heat losses, and the promotion of premixed-like combustion through adequate jet momentum for optimal performance of NH₃-fueled RRQL systems.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105791"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724632","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":"Kinetic study of ozone-sensitized low- and high-temperature oxidation of dimethyl carbonate","authors":"Bowen Liu,&nbsp;Rui Bo,&nbsp;Hao Zhao","doi":"10.1016/j.proci.2025.105788","DOIUrl":"10.1016/j.proci.2025.105788","url":null,"abstract":"<div><div>The low- and high-temperature oxidation of dimethyl carbonate (DMC), a key electrolyte component in lithium-ion batteries (LIBs), was carried out with ozone (O₃) addition by using an atmospheric pressure Jet Stirred Reactor (JSR) from 400 to 1200 K. Kinetic analysis of DMC oxidation was conducted using the coupled Plug Flow Reactor-Perfectly Stirred Reactor (PFR-PSR) module. Without O₃ addition, the oxidation of DMC initiated at 950 K with no low-temperature reactivity. However, the low-temperature chemistry of DMC was observed from 450 K with O₃ addition, and O₃ significantly enhanced the low-temperature reactivity of DMC. Two kinetic models with incorporating the O₃ sub-model were employed and predicted the experimental data reasonably well, even though slightly overpredicted DMC oxidation above 550 K under the fuel-lean condition. Furthermore, a temperature-independent coefficient (TIC) behavior of DMC with O₃ addition was observed between 600 and 950 K both in experiments and simulations, which was associated with the pyrolysis of DMC radicals to CH₂O and CO₂, and then to CO, while the low-temperature oxidation pathway through 1^st and 2^nd O₂ addition and CO oxidation to CO₂ was negligible. The fast pyrolysis reaction rates of O₃ and DMC radicals, such as CH₃OC(=O)OCH₂ and CH₃OC(=O), explain the TIC behavior in the pathway and sensitivity analyses. This work used O₃ to mimic the oxidizing environment in LIBs by providing active atomic oxygen, and implied that the early degradation of LIBs could be attributed to the low-temperature oxidation of DMC with reactive oxygen species. It provides kinetic evidence for a higher level of CO₂ and a lower level of CO in the initial stage of the thermal runaway in LIBs.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105788"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780514","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":"Structure and nitrogen oxide emissions of confined turbulent hydrogen jet flames","authors":"T.L. Howarth ,&nbsp;S. Nerzak ,&nbsp;P. Gruhlke ,&nbsp;J.T. Lipkowicz ,&nbsp;L. Panek ,&nbsp;S. Pfadler ,&nbsp;M. Gauding ,&nbsp;H. Pitsch","doi":"10.1016/j.proci.2025.105851","DOIUrl":"10.1016/j.proci.2025.105851","url":null,"abstract":"<div><div>In this work, a database analysis of three-dimensional direct numerical simulations using detailed chemistry is presented considering a turbulent lean premixed hydrogen/air round jet flame at elevated pressure and temperature (<span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>5</mn><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>u</mi></mrow></msub><mo>=</mo><mn>530</mn><mtext>K</mtext><mo>,</mo><mi>p</mi><mo>=</mo><mn>8</mn><mi>atm</mi></mrow></math></span>), subject to different levels of domain confinement by solid walls. It is shown that for sufficiently small domain sizes, a coherent recirculation zone is present as expected; however, this does not affect the flame structure, consistent with experiments of attached hydrogen flames. Examination of velocity statistics indicates that, while both turbulent kinetic energy and Reynolds shear stresses increase with increasing domain size, these changes occur sufficiently far away from the flame. Each of the flames experiences the same level of mean shear, leading to the same flame structure. Despite identical turbulence-flame interactions between cases, nitrogen oxide (NO) emissions from the flames are observed to be different. For flames with recirculation zones comparable in size to the flame height, the superadiabatic temperatures caused by intrinsic flame instability are retained within the recirculation zone. Often, residence times in the post-flame are too short for locally elevated temperatures to have a significant impact on thermal NO formation. However, when these higher temperatures are coupled with the long fluid residence time in the recirculation zone, despite lower global residence times, this analysis shows that NO emissions from the flame can be enhanced.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105851"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104442","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":"Microgravity flame extinction induced by a moving air vortex ring","authors":"Sainan Quan ,&nbsp;Feng Zhu ,&nbsp;Jinglong Lyu ,&nbsp;Caiyi Xiong ,&nbsp;Xinyan Huang ,&nbsp;Shuangfeng Wang","doi":"10.1016/j.proci.2025.105825","DOIUrl":"10.1016/j.proci.2025.105825","url":null,"abstract":"<div><div>With the growth of outer space exploration missions, a safe, effective and clean fire extinguishing in microgravity spacecraft environment is critical. This paper explores the microgravity flame extinction dynamics induced by a moving air vortex ring. Tests were conducted both on the ground and in microgravity by a drop tower for comparison. An electromagnetic piston-tube system was designed to produce well-controlled air vortex ring to extinguish candle flames with different heat release rates (HRRs). We found a linear extinction boundary correlating the flame HRR with the Reynolds number and characteristic thickness of vortex ring. The flame extinguishing efficiency of air vortex ring in microgravity is 30 % higher than that on the ground. To explain the underlying mechanism, the flame stretch rate that accounts for the unsteady effect, i.e., the competition between external disturbance and flame self-stabilization, was examined. The absence of gravity and buoyancy has a minimum effect on the vortex ring but reduces the oxygen supply and flame diffusion, thereby the flame in microgravity is more vulnerable to vortex ring disturbance. The power of generating a vortex ring is 2–3 orders of magnitude lower than the HRR of flame that it can extinguish, and such a power requirement can be further reduced by 20–30 % in microgravity. This work reveals limiting conditions of vortex ring-induced flame extinction in microgravity and helps design future clean firefighting system for space travel.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105825"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145104445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flame characteristics and lift-off dependencies of flames stabilized on a multi hydrogen jet in swirled crossflow burner","authors":"Lars Koch,&nbsp;Julian Bajrami,&nbsp;Friedrich Dinkelacker","doi":"10.1016/j.proci.2025.105878","DOIUrl":"10.1016/j.proci.2025.105878","url":null,"abstract":"<div><div>This study investigates the stabilization and lift-off behaviour of flames on a multi-hydrogen jet in a swirled crossflow burner under thermal powers ranging from 3 to 17 kW, equivalence ratios from 0.1 to 1.2, and swirl numbers from 0 to 1.79. Depending on the operational conditions, five different flame types can be stabilized. These flames can be distinguished by their anchoring: either anchored at the jet orifices or lifted and stabilized aerodynamically within the shear layer of hydrogen and air. The transitional behaviour of these flame architypes was examined using OH-PLIF, visible chemiluminescence images and stereo-PIV data of the isothermal flow field. Flame shapes during anchoring are primarily influenced by the formation of an inner recirculation zone (IRZ), determined by the crossflow swirl and the equivalence ratio. The imparted swirling motion of the crossflow is reduced due to the radial injection of hydrogen, resulting in an effective swirl number that governs the vortex breakdown. This promotes the formation of an additional reaction zone within the IRZ. Lift-off occurs by increasing the crossflow velocity until the anchored jet flames blow out and an edge flame stabilizes in low-velocity regions of the hydrogen-air shear layer. The lift-off behaviour is similarly governed by the effective swirl number. Increasing the effective swirl number causes a tangential deflection of the anchored flame jets, resulting in a spiral jet path. This motion increases jet-to-jet interactions, leading to merging of several flame jets and increased stability, leading to higher crossflow velocities required to detach the flame. The study’s results highlight the importance of carefully balancing the advantages of increased crossflow swirl, such as enhanced mixing, flame compactness and stability, against the diminished operational range in the lifted regime and proposes an effective swirl number as guidance for the injector design using multi-jet in a swirl crossflow configuration.</div></div>","PeriodicalId":408,"journal":{"name":"Proceedings of the Combustion Institute","volume":"41 ","pages":"Article 105878"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216409","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}