Combustion and Flame最新文献

{"title":"C3MechLite: An integrated component library of compact kinetic mechanisms for low-carbon, carbon neutral and zero-carbon fuels","authors":"Yuki Murakami ,&nbsp;Quan-De Wang ,&nbsp;Shuaishuai Liu ,&nbsp;Yuxiang Zhu ,&nbsp;Pengzhi Wang ,&nbsp;Luna Pratali Maffei ,&nbsp;Raymond Langer ,&nbsp;Tiziano Faravelli ,&nbsp;Heinz Pitsch ,&nbsp;Stephen J Klippenstein ,&nbsp;Jeff Bergthorson ,&nbsp;Gilles Bourque ,&nbsp;Scott Wagnon ,&nbsp;Peter Kelly Senecal ,&nbsp;Henry Curran","doi":"10.1016/j.combustflame.2025.114410","DOIUrl":"10.1016/j.combustflame.2025.114410","url":null,"abstract":"<div><div>Based on our latest detailed chemical reaction mechanism, C3MechV4.0, we have developed two reduced reaction mechanisms—C3MechLite and C3MechCore—targeting C₀–C₃ chemical species including NH₃. C3MechLite (61 species), contains a number of species comparable to GRI-Mech (53 species), that can accurately predict the combustion characteristics of hydrogen, carbon monoxide, ammonia, methane, natural gas, nitrogen oxides, and their mixtures for a wide range of conditions. C3MechCore (118 species) targets a more comprehensive range of C₀–C₃ fuels, including ammonia, methanol, ethanol, and dimethyl ether. Both mechanisms demonstrate predictive accuracy comparable to C3MechV4.0 for the combustion characteristics of the target fuels. C3MechLite is designed with a component library structure, enabling further reduction in mechanism size depending on the fuel(s) of interest for 2D/3D numerical simulations. Various combinations of component libraries were validated, and the average prediction error remains within 1 % compared to C3MechLite. Furthermore, the mechanism was applied to 3D LES simulations of H₂ lifted flames and was confirmed to reproduce flame characteristics with high accuracy. C3MechLite and its component library structure enable high-fidelity and computationally efficient chemical kinetic mechanisms, paving the way for application in more complex combustion simulations.</div></div><div><h3>Novelty and significance statement</h3><div>An integrated component library of compact kinetic mechanism is created based on C3MechV4.0, a comprehensive detailed chemical kinetic mechanism. The component library allows users to flexibly control the size of a mechanism to reduce computational costs without losing prediction accuracy. A new reduced chemical kinetic mechanism, C3MechLite, has a comparable number of chemical species (61 species) compared to GRI-Mech (53 species) and is applicable to a wider range of conditions (fuel blends, temperature and pressure) than GRI-Mech, with a comparable level of prediction accuracy as the detailed mechanism. The proposed component library and C3MechLite can be utilized in various simulation types and provide more accurate information of complex combustion phenomena.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"282 ","pages":"Article 114410"},"PeriodicalIF":6.2,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145061357","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":"Synergistic effects of hydrogen enrichment and propane-butane composition on deflagration dynamics of LPG-H2 premixed flame","authors":"Zhenzhen Zhao ,&nbsp;Yuntao Liang ,&nbsp;Xiaoxing Zhong ,&nbsp;Shuanglin Song ,&nbsp;Zhenqi Liu ,&nbsp;Tengfei Chen ,&nbsp;Lei Liu ,&nbsp;Lin Wang","doi":"10.1016/j.combustflame.2025.114467","DOIUrl":"10.1016/j.combustflame.2025.114467","url":null,"abstract":"<div><div>This study systematically investigates the deflagration characteristics of liquefied petroleum gas (LPG) and hydrogen (H₂) premixed fuels, focusing on the influence of hydrogen fraction (<em>X</em>_H) and propane proportion (<em>X</em>_p) in LPG on key parameters such as maximum flame propagation velocity (<em>V</em>_max), maximum pressure (<em>P</em>_max), thermal diffusivity (<em>D</em>_T), and heat loss (<em>Q</em>). The results reveal that when <em>X</em>_H is low (<em>X</em>_H≤0.2), the <em>V</em>_max increases with the increase of the <em>X</em>_p in LPG, while the <em>P</em>_max decreases. At higher <em>X</em>_H values (<em>X</em>_H&gt;0.2), a synergistic effect between <em>X</em>_H and <em>X</em>_P significantly enhances both <em>V</em>_max and <em>P</em>_max, with the most pronounced effect observed at a high hydrogen fraction (<em>X</em>_H=0.6). Furthermore, increasing both <em>X</em>_H and <em>X</em>_P improves the thermal diffusivity of the premixed fuel while reducing <em>Q</em> to the wall, with a linear negative correlation between the two. These findings indicate that high-diffusivity combustion systems exhibit superior thermal energy utilization efficiency, thereby enhancing the overall combustion reaction efficiency. This study provides critical theoretical insights and empirical data to guide the optimization and efficient utilization of LPG-H₂ premixed fuels.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"282 ","pages":"Article 114467"},"PeriodicalIF":6.2,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047701","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":"Synergy of turbulence and thermo-diffusive effects on the intermittent boundary-layer flashback of swirling flames","authors":"Shiming Zhang ,&nbsp;Zhen Lu ,&nbsp;Yue Yang","doi":"10.1016/j.combustflame.2025.114458","DOIUrl":"10.1016/j.combustflame.2025.114458","url":null,"abstract":"<div><div>We simulated the intermittent boundary-layer flashback (BLF) of hydrogen-enriched swirling flames using large-eddy simulation (LES) with the flame-surface-density (FSD) method. Six cases of intermittent BLF, characterized by periodic flame entry and exit of the mixing tube, are presented. The intermittent BLF characteristics varied with the hydrogen volume fraction. Small flame bulges entered and exited the mixing tube in low hydrogen-enrichment cases. The duration of intermittent BLF events and BLF depth increased as the hydrogen content increased. Meanwhile, a large flame tongue penetrating deeply upstream characterized the highest hydrogen-enrichment case. The mean BLF peak depths and standard deviations obtained through simulations aligned well with experimental data for low and moderate hydrogen-enrichment cases. However, LES-FSD underestimated the average BLF peak depth for the highest hydrogen-enrichment case. Analysis of the flow-flame interaction revealed two mechanisms underlying the intermittent BLF phenomena. The flame bulges’ oscillation near the outlet is caused by the reverse flow induced by the recirculation zone. At the same time, the deep intermittent BLF occurs due to the boundary layer separation induced by the large turbulent burning velocity, resulting from the synergy of turbulence and thermo-diffusive effects.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"281 ","pages":"Article 114458"},"PeriodicalIF":6.2,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045217","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":"Impact of the operating conditions on the OH* distribution and its correlation with the heat release rate in hydrogen–air flames","authors":"Francesco G. Schiavone ,&nbsp;Marco Torresi ,&nbsp;Sergio M. Camporeale ,&nbsp;Davide Laera","doi":"10.1016/j.combustflame.2025.114452","DOIUrl":"10.1016/j.combustflame.2025.114452","url":null,"abstract":"<div><div>OH* chemiluminescence is widely used as heat release rate (HRR) marker in combustion experiments. Still, its suitability for hydrogen–air flames has not been extensively assessed for a wide range of operative conditions and flame archetypes. In the present work, correlations between OH* and HRR spatial distributions are first investigated in one-dimensional unstretched laminar premixed flames at variable pressure ([1; 20] atm), unburned gas temperature ([300; 900] K), and equivalence ratio ([0.3; 3.0]). At atmospheric pressure and unburned gas temperature, two main differences are observed: a characteristic shift between the OH* and HRR peak positions and, for equivalence ratios close to stoichiometry, the presence of a non-negligible concentration of OH* in the post-flame zone, where the HRR value is zero. When pressure and unburned gas temperature are increased, the peak shift is attenuated, while the OH* concentration in the burned gases is favored.</div><div>For lean (<span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>35</mn></mrow></math></span>) and stoichiometric mixtures, the effects of strain and curvature contributions of flame stretch are analyzed in one-dimensional counterflow flames and two-dimensional expanding flames. Higher strain rates slightly affect the peak shift, but sensibly enhance the production of OH* in the burned gas region. Stretch strongly impacts on expanding lean flames, for which the onset of intrinsic instabilities worsens the OH*-HRR correlation, in terms both of distribution shape and intensity.</div><div>Finally, nonpremixed one-dimensional counterflow diffusion flames and a more complex two-dimensional triple flame are analyzed. In both configurations, a significant reduction of the peak shift is observed when the combustion occurs in diffusion-controlled regimes, sustaining the adequacy of OH* as HRR marker for hydrogen–air diffusion flames under various operating conditions.</div><div><strong>Novelty and significance statement</strong></div><div>This work presents a systematic investigation of the OH* distribution and its correlation with the heat release rate in several canonical premixed and nonpremixed laminar hydrogen–air flames under various operating conditions, extending the current literature on the subject.</div><div>The chemical pathways leading to the peculiar behavior observed for stoichiometric flames are investigated, and the interaction of OH* with intrinsic thermodiffusive instabilities in lean flames is analyzed, showing how the correlation with the heat release rate is worsened.</div><div>A coherent methodology to quantitatively assess heat release surrogates, which can be extended to other measurable quantities, is provided too.</div><div>This knowledge is significant as it underlines how the parametric variation of operating conditions can differently affect the correlation between the OH* and the heat release rate distributions, highlighting the limits of OH*chemilum","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"282 ","pages":"Article 114452"},"PeriodicalIF":6.2,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047700","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":"Flamelet models with differential diffusion effects for large eddy simulations of ammonia/hydrogen/nitrogen-air partially premixed jet flames","authors":"Junjun Guo ,&nbsp;Francisco E. Hernández-Pérez ,&nbsp;Zhaohui Liu ,&nbsp;Hong G. Im","doi":"10.1016/j.combustflame.2025.114464","DOIUrl":"10.1016/j.combustflame.2025.114464","url":null,"abstract":"<div><div>Blending ammonia with hydrogen and partially cracking ammonia are promising strategies to enhance the combustion performance of ammonia. Accurate prediction of ammonia/hydrogen blend combustion behavior requires careful consideration of differential diffusion effects associated with hydrogen. In this study, differential diffusion effects are assessed considering various flamelet-based modeling approaches: the unity Lewis number flamelet/progress variable (ULF) model, variable Lewis number flamelet/progress variable (VLF) model, and species-weighted flamelet/progress variable (SWF) model. The latter one incorporates weighting between two flamelet datasets based on the unity Lewis number assumption and the mixture-averaged diffusion models. An <em>a priori</em> analysis based on direct numerical simulation (DNS) data and an <em>a posteriori</em> analysis involving large eddy simulation (LES) of turbulent partially premixed NH₃/H₂/N₂-air jet flame are conducted. The analysis confirms the presence of strong differential diffusion in turbulent partially premixed NH₃/H₂/N₂-air flames and demonstrates the feasibility of weighted flamelet models for properly capturing the differential diffusion effects in different levels of turbulence. Moreover, due to the longer chemical time of NO formation on the fuel-lean side, adding the NO mass fraction in the definition of the progress variable effectively improves NO predictions. In the LES simulations, it is found that the SWF model performs well by considering both turbulent diffusion and molecular diffusion. The predictions of the SWF model fall between those of the ULF and VLF models and align closely with the measurements on fuel-rich side, indicating the significant roles of both turbulent diffusion and molecular diffusion in these regions.</div></div><div><h3>Novelty and Significance Statement</h3><div>This study innovates by conducting comprehensive <em>a priori</em> and <em>a posteriori</em> analyses on modeling differential mass diffusion using flamelet-based models. The <em>a priori</em> analysis based on the DNS data confirms the strong differential diffusion in turbulent partially premixed NH₃/H₂/N₂-air flames, as well as the feasibility of using weighted-based flamelet models for the modeling of differential diffusion. LES simulations further reveal that differential diffusion is more pronounced on the fuel-rich side than on the fuel-lean side.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"281 ","pages":"Article 114464"},"PeriodicalIF":6.2,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045337","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 NH* chemiluminescence and NO formation mechanisms in CH4/NH3 co-flow diffusion flames: A computational kinetic perspective","authors":"Yang Liu ,&nbsp;Qinghua Guo ,&nbsp;Yan Gong ,&nbsp;Guangsuo Yu","doi":"10.1016/j.combustflame.2025.114462","DOIUrl":"10.1016/j.combustflame.2025.114462","url":null,"abstract":"<div><div>NH*, a characteristic radical in ammonia-blended flames, is a critical parameter for evaluating combustion efficiency and kinetic characteristics through its chemiluminescence properties. In this work, numerical investigations were conducted on NH* chemiluminescence and NO formation mechanisms in CH₄/NH₃ diffusion flames at different ammonia blending ratios using a modified Okafor 2018 reaction mechanism. A two-dimensional distribution of NH* chemiluminescence was obtained using a spectral detection platform with 337 nm and 355 nm filters for NH* background radiation subtraction. The NH* emission was mainly concentrated in the upstream region of the diffusion flame near the fuel outlet, and the peak intensity showed a non-monotonic variation with increasing ammonia blending ratio-initially rising and then decaying. It was found that the collisional quenching reactions NH* + M&lt;=&gt;NH + M and NH* + NH₃&lt;=&gt;NH + NH₃ were considered the main quenching pathways for NH* in CH₄/NH₃ flames. The generation reactions were N₂* + NH&lt;=&gt;N₂+ NH* and CH + NO&lt;=&gt;NH* + CO. HNO, NH and NH₂ were the key species influencing NO generation and consumption. The main generation reactions of HNO were NH + OH&lt;=&gt;HNO + H and NH₂ + O&lt;=&gt;HNO + H, which gradually increased with increasing ammonia blending ratio. In addition, the correlation between NH* and NO distribution was analyzed. NH* can characterize the distribution core of NO.</div><div><strong>Novelty and significance statement:</strong> The first development of a refined kinetic mechanism integrating detailed NH*/N₂* mechanisms with the Okafor mechanism was presented, overcoming the critical limitation in existing models for predicting NH* chemiluminescence in the ammonia flame. This provided a validated tool for quantitative analysis of radicals in CH₄/NH₃ combustion systems. NH* chemiluminescence was identified as a novel optical marker for characterizing ammonia combustion dynamics in our study, with previously unreported correlations between NH* formation, quenching processes, and ammonia blending ratios being revealed. It established a new methodology for non-intrusive monitoring of ammonia-blended combustion. Furthermore, we elucidated of the dual-phase relationship between NH* evolution and NO formation pathways, uncovering the key mechanisms and two-dimensional distribution patterns of pollutant NO. These findings provided important insights for developing spectroscopy-based optimization strategies to enhance combustion efficiency and reduce NO emissions in ammonia-blended flames.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"281 ","pages":"Article 114462"},"PeriodicalIF":6.2,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045403","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":"Enhanced detonation shock dynamics prediction for curvature-driven detonation propagation in annular channels","authors":"Kang Tang ,&nbsp;Gang Dong ,&nbsp;Zhenhua Pan ,&nbsp;Mingyue Gui","doi":"10.1016/j.combustflame.2025.114456","DOIUrl":"10.1016/j.combustflame.2025.114456","url":null,"abstract":"<div><div>This study extends the Detonation Shock Dynamics (DSD) theory, originally developed for condensed-phase explosives, to predict the steady propagation of curved gaseous detonation waves in an annular channel filled with C₂H₂/O₂/Ar mixtures. The theory framework couples a steady-state level-set formulation with a <em>D</em>_n − <em>κ</em> relationship derived from a generalized ZND model, and incorporates shock polar analysis to impose the outer wall boundary condition. This enables the computation of the detonation shock front’s steady shape and angular velocity. The model is validated against two-dimensional simulations using the same detailed chemical kinetics. Results show that, for a fixed inner radius of the annular channel and initial pressures from 10 to 80 kPa, when outer radius of the annular channel (<em>r</em>_o) is larger than a critical radius (<em>r</em>_cr1), the angular velocity of propagating detonation wave predicted by the DSD method remains invariant with respect to variations in <em>r</em>_o or the outer wall normal angle (<em>φ</em>_o). To address underprediction of the angular velocity at low pressures, an enhanced <em>D</em>_n − <em>κ</em> relationship is proposed to account for effect induced by transverse wave collisions. The improved model demonstrates excellent agreement with simulations across all tested pressures. Two critical outer radii are identified: a lower limit radius (<em>r</em>_cr1) reflecting the extent of the Detonation-Driven Zone (DDZ) and an upper limit radius (<em>r</em>_cr2) associated with the transition in shock reflection modes. These radii define the annular width range that supports self-similar detonation propagation. The results underscore the potential of the DSD method as a fast and reliable tool for optimizing annular combustion chamber design in rotating detonation engines (RDEs).</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"281 ","pages":"Article 114456"},"PeriodicalIF":6.2,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045402","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":"Neural network-based 3D reconstruction of temperature and velocity for turbulent flames from 2D measurements","authors":"Shiyu Liu,&nbsp;Haiou Wang,&nbsp;Kun Luo,&nbsp;Jianren Fan","doi":"10.1016/j.combustflame.2025.114454","DOIUrl":"10.1016/j.combustflame.2025.114454","url":null,"abstract":"<div><div>Three-dimensional (3D) high-resolution data of temperature and velocity are crucial for achieving a fundamental understanding of turbulent flames. However, existing combustion diagnostics are predominantly limited to the measurements at a point, along a line, or in a two-dimensional (2D) plane. In the present work, for the first time, the potential of neural networks for 3D reconstruction of turbulent combustion based on 2D measurements is explored, aiming to reconstruct both 3D temperature and velocity fields using data from a limited number of 2D planes. First, a novel translation approach incorporating two vector-quantized variational autoencoders (VQ-VAE) and a diffusion transformer model is developed for 3D temperature reconstruction based on 2D temperature distributions. Then, a wavenumber-based physics-informed neural networks (WN-PINNs) framework is established to derive the 3D velocity fields constrained by the momentum equation using the reconstructed 3D temperature and the 2D velocity measurements. The performance of the proposed neural networks is evaluated on two different configurations of turbulent flames, including freely propagating planar premixed combustion and swirling premixed combustion. The reconstructed temperature and velocity are compared with the high-fidelity direct numerical simulation (DNS) data both qualitatively and quantitatively. This study highlights the great potential of machine learning methods for the 3D reconstruction of turbulent flame fields, and provides new insights for the development of complementary tools for conventional diagnostic techniques to alleviate the challenges of 3D measurements in combustion research.</div><div><strong>Novelty and significance</strong></div><div>In the present work, the feasibility of using neural networks for 3D reconstruction of turbulent combustion from a limited number of 2D planes has been explored. A novel translation approach with transfer learning and a wavenumber-based physics- informed neural network framework have been established for 3D reconstruction of both temperature and velocity fields, which is the first of its kind. The proposed neural networks have demonstrated the capability to recover the flow and flame structures, with good agreement compared to high-fidelity direct numerical simulation data. The study highlight the potential of neural networks in bridging the gap between 2D measurements and 3D reconstructions for both scalar and velocity fields, offering new insights in the development of complementary tools for traditional combustion diagnostics.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"281 ","pages":"Article 114454"},"PeriodicalIF":6.2,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045401","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":"Cellular stability of hydrogen–oxygen detonation","authors":"Jonathan Timo Lipkowicz ,&nbsp;Jackson Crane ,&nbsp;Xian Shi ,&nbsp;Irenaeus Wlokas ,&nbsp;Hai Wang ,&nbsp;Andreas Markus Kempf","doi":"10.1016/j.combustflame.2025.114417","DOIUrl":"10.1016/j.combustflame.2025.114417","url":null,"abstract":"<div><div>A detonation cellular stability mechanism based on the dynamics of reactive decaying blasts is examined through detailed analyses of two-dimensional (2D) numerical simulations of hydrogen-oxygen detonations. Different from previous blast-based examinations, we resolve the transient process of decoupling between shock and reaction fronts in decaying blasts, and correlate the size of unburnt gas mixtures behind decaying shocks to that of the subsequent blast kernels. The impact on the stability mechanism of (1) chemical kinetics, (2) diffusive processes, and (3) boundary conditions are examined through a series of simulations. At a dopant level, ozone is known to reduce ignition delay without altering thermodynamic properties of the mixture, enabling investigation of the impact of ignition kinetics on the cellular stability. The addition of ozone leads to a stronger coupling between shock and reaction fronts and stabilizes the blast kernel to a smaller size. The resulting global cell size reduction in the ozonated detonation is well described by the stability analysis and in agreement with experimental cell measurements reported in Crane <em>et al.</em>, <em>Combust. Flame</em> 200 (2019) 44–52. The inclusion of diffusive physics marginally affects the detonation cellular structure, but causes a global propagation speed deficit. Results from two channel heights show that cell size increases in the smaller channel due to mode-locking. A detailed grid convergence study is performed, which examines both kinetic and macroscopic structural features as a function of grid resolution. The results of the stability analysis is independent of numerical grid resolution.</div><div><strong>Novelty and Significance Statement</strong></div><div>This work develops a novel theory for detonation cellular stability, enabling the prediction of detonation cell size and instabilities. Theory validation leverages the statistical analysis of blast propagation and decoupling, which is an entirely new way of post-processing detonation simulation. This work also presents the first time, to our knowledge, the link between molecular viscosity and cellular structure has been isolated, accomplished through a set of simulations using both Navier-Stokes and Euler equations, and several boundary conditions. This work is impactful because it enables and validates the modeling of detonation propagation behavior using a blast-based construct. This blast-based construct is many orders of magnitude less expensive as compared to conventional CFD.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"281 ","pages":"Article 114417"},"PeriodicalIF":6.2,"publicationDate":"2025-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010141","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":"Consumable embedded microwave Antenna in AP/HTPB propellant to focus energy at the reaction front","authors":"Keren Shi,&nbsp;Erik Hagen,&nbsp;Yujie Wang,&nbsp;Michael R. Zachariah","doi":"10.1016/j.combustflame.2025.114304","DOIUrl":"10.1016/j.combustflame.2025.114304","url":null,"abstract":"<div><div>This study demonstrates a novel method to modulate the burn rate of AP/HTPB propellants by embedding a <em>consumable</em> microwave (MW) antenna, which can be directly coupled to a MW source. The tip of the antenna, which is being consumed, is thus always at the burning surface of the propellant and radiates MW energy to weakly absorbing HTPB. We found a significant increase in burn rate (up to ∼2X), with increasing MW power, despite the fact that the flame temperatures were unaffected. These results indicated that the function of the antenna was restricted to delivering power to the condensed phase. Electric field simulation indicates that the MW energy focused at the burning surface and along the axial direction along the MW antenna. This study shows that focusing on MW energy on the burning surface can be used to modulate burn rate of propellants by embedding a consumable MW antenna.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"281 ","pages":"Article 114304"},"PeriodicalIF":6.2,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004360","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}