Combustion and Flame最新文献

{"title":"Real-fluid behavior in rapid compression machines: Does it matter?","authors":"Mingrui Wang ,&nbsp;S. Scott Goldsborough ,&nbsp;Song Cheng","doi":"10.1016/j.combustflame.2025.114384","DOIUrl":"10.1016/j.combustflame.2025.114384","url":null,"abstract":"<div><div>Rapid compression machines (RCMs) have been extensively used to quantify fuel autoignition chemistry and validate chemical kinetic models at high-pressure conditions. Historically, the analyses of experimental and modeling RCM autoignition data have been conducted based on the adiabatic core hypothesis with ideal gas assumption, where real-fluid behavior has been completely overlooked, though this might be significant at common RCM test conditions. This work presents a first-of-its-kind study that addresses two significant but overlooked questions for autoignition studies within RCMs in the fundamental combustion community: (i) experiment-wise, can unaccounted-for real-fluid behavior in RCMs affect the interpretation and analysis of RCM experimental data? and (ii) simulation-wise, can unaccounted-for real-fluid behavior in RCMs affect RCM autoignition modeling and the validation of chemical kinetic models? To this end, theories for real-fluid isentropic change are newly proposed and derived based on high-order Virial EoS, and are further incorporated into an effective-volume real-fluid autoignition modeling framework newly developed for RCMs. With detailed analyses, the strong real-fluid behavior in representative RCM tests is confirmed, which can greatly influence the interpretation of RCM autoignition experiments, particularly the determination of end-of-compression temperature and evolution of the adiabatic core in the reaction chamber. Furthermore, real-fluid RCM modeling results reveal that considerable error can be introduced into simulating RCM autoignition experiments when following the community-wide accepted effective-volume approach by assuming ideal-gas behavior, which can be as high as 64% in the simulated ignition delay time at compressed pressure of 125 bar and lead to contradictory validation results of chemical kinetic models. Therefore, we recommend the community to adopt frameworks with real-fluid behavior fully accounted for (e.g., the one developed in this study) to analyze and simulate past and future RCM experiments, so as to avoid misinterpretation of RCM autoignition experiments and eliminate the potential errors that can be introduced into the simulation results with the existing RCM modeling frameworks.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114384"},"PeriodicalIF":5.8,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144710984","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":"Surrogate formulation for HEFA sustainable aviation fuels: a new approach based on pyrolysis experiments","authors":"Yilun Liang,&nbsp;Juan Wang","doi":"10.1016/j.combustflame.2025.114366","DOIUrl":"10.1016/j.combustflame.2025.114366","url":null,"abstract":"<div><div>Pyrolysis experiments were conducted in a flow reactor at atmospheric pressure on three distinct hydroprocessed esters and fatty acids synthetic paraffinic kerosene (HEFA-SPK) fuels, with species concentration profiles obtained via online gas chromatography (GC). The results indicated similar pyrolysis characteristics across the fuels. A surrogate for HEFA-SPK was developed by selecting n-dodecane and isododecane as the surrogate components. The ratio of these components was determined based on the concentration profiles of pyrolysis products. A detailed kinetic model for the n-dodecane and isododecane mixture was developed, encompassing 2464 species and 8939 reactions, to simulate pyrolysis across various composition ratios and identify the optimal surrogate composition. Simulations highlighted the sensitivity of C₂H₄, C₂H₆, C₃H₄-A, and C₃H₄-P concentration profiles to the n-dodecane and isododecane ratio. These profiles served as matching targets to ascertain the optimal composition, yielding a surrogate of 73 % n-dodecane and 27 % isododecane by weight. Validation against experimental data, including pyrolysis data from this study and oxidation species concentration and ignition delay time data from literature, confirmed the surrogate's ability in replicating HEFA-SPK's combustion characteristics and the method's validity. Furthermore, a skeletal mechanism for the surrogate, comprising 66 species and 186 reactions, was developed and validated against literature data, demonstrating its accuracy in predicting the oxidation behavior of pure n-dodecane, pure isododecane, and HEFA-SPK.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114366"},"PeriodicalIF":5.8,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144710982","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 Di-tert-butyl peroxide combustion: time-resolved speciation, laminar flame speed, and model evaluation","authors":"Congjie Hong ,&nbsp;Jiabiao Zou ,&nbsp;Janardhanraj Subburaj ,&nbsp;Ayman M. Elbaz ,&nbsp;William L. Roberts ,&nbsp;Yingjia Zhang ,&nbsp;Zuohua Huang ,&nbsp;Aamir Farooq","doi":"10.1016/j.combustflame.2025.114350","DOIUrl":"10.1016/j.combustflame.2025.114350","url":null,"abstract":"<div><div>Di‑tert‑butyl peroxide (DTBP), a cetane improver, consists of two tert‑butoxy groups bonded by a weak peroxide bond. A thorough understanding of the combustion mechanisms of DTBP is essential for its effective use as a fuel additive. This study systematically investigates the pyrolysis and oxidation characteristics of DTBP through a combination of experimental measurements and kinetic modeling. Laser absorption spectroscopy was employed to achieve time-resolved quantification of key species, including CO, CO₂, OH, and H₂O, during DTBP pyrolysis and oxidation under conditions spanning 1265 - 2000 K and 1.1 - 1.6 bar. The laminar flame speed of DTBP was measured for the first time over a range of equivalence ratios (0.65 - 1.4), initial pressures (0.5 - 2 bar), and a fixed initial temperature of 373 ± 3 K. These experimental results provide essential constraints for optimizing and validating the DTBP kinetic model. The proposed model significantly improved the accuracy of predictions for ignition delay times and laminar flame speeds. Furthermore, the model demonstrated excellent performance in capturing the second-stage ignition delay, overcoming the limitations of previous models. However, the current model still exhibits noticeable deviations in predictions below 1300 K, particularly in the formation dynamics of key species such as CO. To improve the model’s accuracy under these conditions, further high-fidelity quantum chemical calculations are needed to refine the rate constants of additional unimolecular decomposition and hydrogen abstraction pathways of DTBP. Overall, by incorporating the latest sub-mechanism of acetone oxidation and updated rate constants for DTBP decomposition reactions, this study provides valuable experimental data and kinetic insights to advance combustion kinetic models for oxygenated fuels and support the development of high-efficiency combustion technologies.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114350"},"PeriodicalIF":5.8,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695015","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":"Advancing ammonia-hydrogen combustion reaction kinetics: Informative experimental datasets constructed through global-sensitivity-based clustering","authors":"Chenyue Tao,&nbsp;Yiru Wang,&nbsp;Chengcheng Liu,&nbsp;Bin Yang","doi":"10.1016/j.combustflame.2025.114353","DOIUrl":"10.1016/j.combustflame.2025.114353","url":null,"abstract":"<div><div>Ammonia has emerged as a highly promising zero-carbon energy carrier in recent years. To address its combustion challenges, blending with hydrogen has been proposed as an effective solution. This approach necessitates a comprehensive understanding of the underlying reaction kinetics for practical implementation. The extensive experimental data available on NH₃/H₂ combustion offers the potential for advancing chemical kinetics understanding through model optimization. However, effectively utilizing the extensive dataset poses significant challenges, primarily due to prohibitively high computational costs when processing large volumes of data for model optimization. Moreover, indiscriminate use of all available data without proper quality assessment is inadvisable, given the potential issues of data inconsistency. To comprehensively extract kinetic information from existing experimental dataset and facilitate efficient model development, this study implements a global-sensitivity-based clustering approach. The 2786 NH₃/H₂ experimental data are categorized into 40 distinct clusters. Representative exemplars from each cluster are selected to construct a streamlined yet information-dense dataset, which is subsequently employed for model optimization, resulting in a substantial enhancement of the model's predictive performance. Although information redundancy exists in current datasets, certain aspects of reaction kinetics may remain unexplored due to limitations in existing experimental data. Within the range of experimental conditions that current experimental equipment can cover, there are still many unexplored condition regions. To investigate the potential impact of conducting experiments under these new conditions on advancing NH₃/H₂ combustion modeling, we systematically extend the dataset to incorporate 6695 theoretically feasible experimental conditions. Notably, eight previously insensitive reactions demonstrate significant sensitivity within this expanded framework. Furthermore, eleven additional prospective experimental conditions exhibiting high sensitivity to these eight parameters are identified and incorporated into the existing informative dataset. Subsequent model optimization utilizing this enhanced dataset of 51 elements yields significantly improved performance. This study demonstrates that carefully-designed future experiments can provide novel insights into the reaction kinetics of ammonia-hydrogen combustion kinetics, as well as offering valuable guidance for future experimental investigations.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114353"},"PeriodicalIF":5.8,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686485","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":"Characterization and modeling of the flame response to high frequency propellant flow rates oscillations in the framework of thermo-acoustic instabilities in liquid rocket engines","authors":"Thomas Schmitt ,&nbsp;Robin Nez ,&nbsp;Sébastien Ducruix","doi":"10.1016/j.combustflame.2025.114326","DOIUrl":"10.1016/j.combustflame.2025.114326","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Pressure fluctuations induced by thermoacoustic self-sustained oscillations within the combustion chamber or the feeding domes (plenums) of a liquid rocket engine may induce temporal modulations of the injection velocities of the propellants. The dynamic response of a transcritical coaxial flame to such a modulation is investigated here as it is thought to be one of the mechanisms that can promote high frequency combustion instabilities in liquid rocket engines. This question is addressed through large eddy simulations of a single LOx/GCH&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; coaxial flame, representative of next generation injection systems. Each of the propellant streams is successively acoustically modulated so that a harmonic flow rate oscillation is achieved. The unsteady heat release rate response of the flame is recorded and hydrodynamic features caused by the modulation are identified. It is first shown that both fuel and oxidizer flow rates, if unsteady, have the potential to trigger high amplitude heat release rate oscillations within frequency ranges that are typical of high frequency instabilities in liquid rocket engines. The fuel-modulated configuration is essentially linear even for high modulation amplitudes (at least up to 40%). On the contrary, the oxidizer-modulated case shows a strong dependence of the gain in terms of the modulation amplitude, while its phase remains virtually unaffected (at least up to 10% of the modulation amplitude in the present study). This study then reveals that both unsteady propellant injections can induce flame surface oscillations as well as variations of the rate of heat released by a unit flame surface element, explaining the unsteady heat release rate observed. The relative contributions of these two driving mechanisms are measured. They prove to be complex and strongly dependent on the modulation frequency. Reduced order models of the resulting flame response are finally proposed. The fuel-modulated case is modeled assuming a local increase of the turbulent mixing provoked by the annular velocity modulation. The oxidizer-modulated case is represented by an oscillation of flame length due to the inner stream modulation. Provided that a mean unmodulated and one modulated solutions are available, both models can give accurate predictions for a large range of frequencies, both in terms of gain and phase. In particular, the oxidizer model is natively non-linear and permits to retrieve the modulation amplitude dependence observed in the simulations.&lt;/div&gt;&lt;div&gt;&lt;strong&gt;Novelty and Significance Statement&lt;/strong&gt;&lt;/div&gt;&lt;div&gt;The response of a cryogenic flame to the effect of the modulated injector flows is weakly documented in the literature, while being of high interest for the modeling and prediction of combustion instabilities in liquid rocket engine. Modulated flames are depicted in Nez et al. (2017) and Laurent et al. (2021), but only for a modulation of","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114326"},"PeriodicalIF":5.8,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686486","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":"Large-eddy simulation analysis of turbulent flame periodic flashbacks in a backward-facing step (BFS) combustor","authors":"Jean-Michel Klein ,&nbsp;Aurelien Genot ,&nbsp;Axel Vincent-Randonnier ,&nbsp;Arnaud Mura","doi":"10.1016/j.combustflame.2025.114335","DOIUrl":"10.1016/j.combustflame.2025.114335","url":null,"abstract":"<div><div>Highly turbulent premixed flame dynamics is studied in a backward-facing step combustor. Large-eddy simulations are performed for two operating conditions: (i) a stable case with the flame anchored in the vicinity of the sudden expansion and (ii) an unstable case with massive periodic flashbacks. This set of computational results is first assessed through comparisons with experimental data. Then, it is used to conduct a detailed analysis of the flashback process. Pressure and velocity fluctuations signals display (i) high frequency fluctuations associated to turbulence with similar amplitudes in both the stable and unstable cases, and (ii) a low frequency fluctuation, of acoustic origin, the amplitude of which is significantly higher in the unstable case. The occurrence of flame flashback is found to be closely related to the structure of the first longitudinal acoustic mode, which can be modified thanks to a throttling plug used to modulate the area of the combustor exit cross-section. In the unstable case, this corresponds to an axial-velocity anti-node at the backward-facing step location. Pressure variations are synchronized with the motions of the flame toward the combustor upper wall and the cross-correlation between pressure and heat-release rate oscillations is relevant to a thermoacoustic feedback.</div><div><strong>Novelty and significance statement</strong></div><div>The present computational study is devoted to the analysis of highly turbulent flame periodic flashbacks in a BFS combustor. It includes three principal contributions. First of all, it demonstrates the capability of the retained computational approach to satisfactorily retrieve flame dynamics and complex phenomena, as observed in experiments, for both conditions (i.e., stable and unstable). Then, it confirms that the presence of the needle at the outlet nozzle leads to the birth of a velocity anti-node in the BFS direct vicinity (i.e., at the flame location). Finally, it provides a detailed characterization of the thermoacoustic behavior of the combustor, putting into evidence the coupling of turbulence and acoustic-induced oscillations with the unsteady motion of the flame and the structure of the acoustic field.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114335"},"PeriodicalIF":5.8,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144678825","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":"On the facility independence of inhomogeneous ignition processes in shock tubes: propane/air ignition at low temperature and intermediate pressure","authors":"Matthew G. Sandberg ,&nbsp;Damien Nativel ,&nbsp;Sean P. Cooper ,&nbsp;Matthew Intardonato ,&nbsp;Matthew K. Hay ,&nbsp;Mustapha Fikri ,&nbsp;Jürgen Herzler ,&nbsp;Waruna D. Kulatilaka ,&nbsp;Eric L. Petersen ,&nbsp;Christof Schulz","doi":"10.1016/j.combustflame.2025.114356","DOIUrl":"10.1016/j.combustflame.2025.114356","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The interpretation of fuel/air ignition delay times measured in shock-tube experiments becomes challenging at low temperatures and low dilution levels due to inhomogeneous ignition phenomena across the test gas. The rapid growth of a turbulent boundary layer at the wall of the shock tube introduces non-ideal, gas-dynamic effects that can disturb the conditions behind the reflected shock wave, especially at longer test times, potentially causing localized ignition. The magnitude of such effects may vary between shock-tube facilities, but their influence on ignition may not necessarily be facility-dependent. To better understand this phenomenon, ignition delay time and high-speed chemiluminescence imaging measurements for lean and stoichiometric C&lt;sub&gt;3&lt;/sub&gt;H&lt;sub&gt;8&lt;/sub&gt;/O&lt;sub&gt;2&lt;/sub&gt;/diluent mixtures have been performed in two different shock-tube facilities at two different laboratories that differ in geometry. C&lt;sub&gt;3&lt;/sub&gt;H&lt;sub&gt;8&lt;/sub&gt;/O&lt;sub&gt;2&lt;/sub&gt; mixtures were diluted in both N&lt;sub&gt;2&lt;/sub&gt; and Ar with diluent/O&lt;sub&gt;2&lt;/sub&gt; volume ratios maintained at 3.76/1. Temperatures behind the reflected shock wave ranged from 900 to 1400 K at reflected-shock pressures of 6 to 8 bar. Mixture-averaged d&lt;em&gt;p&lt;/em&gt;/d&lt;em&gt;t&lt;/em&gt; values are reported at 0.5 to 2.0 %/ms in the N&lt;sub&gt;2&lt;/sub&gt;-diluted mixtures and up to 4.0 %/ms in the Ar-diluted mixtures. The ignition delay time results are compared to simulations based on the NUIGMech 1.3 mechanism under both constant-volume conditions and incorporating facility-dependent d&lt;em&gt;p&lt;/em&gt;/d&lt;em&gt;t&lt;/em&gt;. Measured ignition delay times begin to depart from model predictions at 1050 K, forming a ‘roll-off’ region, where inhomogeneities accelerate ignition. These non-uniformities were first observed in both facilities at UDE and TAMU using pressure and chemiluminescence diagnostics and later confirmed at TAMU with endwall high-speed imaging during ignition. The measurements reveal that flame kernels appear up to 3 ms before the main ignition event, ultimately leading to shorter ignition delay times when compared to model predictions. Additionally, localized ignition appears to occur at the sidewall first, where larger temperature non-uniformities may exist due to interactions between the shock-heated gas and the turbulent boundary layer. This work extends inhomogeneous ignition studies in shock tubes by showing that such nonideal behavior is reproducible at similar conditions in two different shock-tube facilities from two different laboratories. Our results indicate that fluid-mechanic instabilities considerably influence the ignition process for post-reflected-shock temperatures below 1225–1326 K, depending on the criteria imposed on the definition of a bifurcation timescale. Experiments conducted in Ar-diluted mixtures containing 10 and 20 percent helium by volume were generally inconclusive, and it was determined that greater quantities of helium may be necessary to promote homogeneous ignition at the conditio","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114356"},"PeriodicalIF":5.8,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144678824","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":"The propagation behavior of high-speed divergent deflagrations in a thin gap chamber","authors":"Chenyang Wang,&nbsp;Bo Zhang","doi":"10.1016/j.combustflame.2025.114359","DOIUrl":"10.1016/j.combustflame.2025.114359","url":null,"abstract":"<div><div>Investigating the combustion characteristics of fuel mixtures in thin channels enhances the understanding of the combustion process and safety in various applications. Previous studies of flame propagation behavior in thin gap chambers focused on low-speed flames and detonations, with a lack of research on high-speed deflagrations with flame propagation velocity (FPV) of hundreds of meters per second. This study investigated the propagation behavior of such high-speed divergent deflagration in a thin gap chamber by using a stoichiometric ethylene–oxygen mixture. FPV fluctuations during the propagation were observed for the first time. The effects of the initial pressure (6–20 kPa) and the chamber radius (60 mm, 75 mm, 90 mm) were analyzed. The results show that higher initial pressures amplify FPV fluctuations, increase the maximum FPV, and enhance flame front wrinkling, while smaller chamber radii shift fluctuation positions earlier in time and absolute position. The relative position of the critical FPV deceleration point in the first fluctuation in the near-wall stage exponentially converges to 0.825 as pressure increases, independent of the chamber radius. Key mechanisms for FPV fluctuations in the two propagation stages were identified: 1) In the initial FPV fluctuation stage, reflected pressure waves from the chamber wall interact with the flame front, reversing local flow and causing deceleration. 2) In the near-wall fluctuation stage, competition between outward deflagration propagation and pressurization of unburned gas leads to cyclic acceleration-deceleration patterns, including temporary contraction. These findings provide fresh insights into the behavior of high-speed deflagrations in thin chambers and have practical significance for combustion system design and safety measures.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114359"},"PeriodicalIF":5.8,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144672484","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 and reaction kinetics study of CO2-driven ABC powder on suppressing liquefied petroleum gas explosion","authors":"Qiuhong Wang ,&nbsp;Jianxiong Liu ,&nbsp;Guoqiang Dong ,&nbsp;Bin Peng ,&nbsp;Yifei Liu ,&nbsp;Jian Chen ,&nbsp;Fuxin Chen ,&nbsp;Leilei Zhu ,&nbsp;Xiang Fang ,&nbsp;He Zhu","doi":"10.1016/j.combustflame.2025.114351","DOIUrl":"10.1016/j.combustflame.2025.114351","url":null,"abstract":"<div><div>Leakage of liquefied petroleum gas (LPG) during transportation and storage could lead to explosions, posing a substantial environmental and public safety risk. Therefore, the effectiveness of CO₂-driven ABC powders (CO₂/ABC composite suppressant) in mitigating LPG explosions was investigated at the experimental and reaction kinetics levels. This study identified the optimal combination of CO₂ and ABC powder, revealing their synergistic suppression mechanisms. The results demonstrated that the composite inhibitor outperformed the single inhibitor, primarily due to its synergistic effect. CO₂ pronouncedly affected <em>P</em>_max, while ABC powder influenced (d<em>P</em>/d<em>t</em>)_max. Experimental and reaction kinetics analyses determined the optimal combination of 9 vol% CO₂ (161.91 g·m^–3 CO₂) +250 g·m^–3 ABC. The optimal combination lessened the peak total rate of production (<em>ROP</em>) of H, O, and OH radicals of LPG (6 vol%) by 98.04%, 99.59%, and 98.34%, respectively. The corresponding mole fractions were decreased by 85.55%, 96.16%, and 80.88%. The heat release rate is reduced by 98.08%. Physical inhibition primarily relies on two mechanisms: the dilution and heat-absorption effects of CO₂ and the heat absorption during NH₄H₂PO₄ decomposition. Chemically, HOPO₂, PO₂, HNO, NH₂, and NH₃ exhibited strong free radical depletion. Among them, NH₃+OH&lt;=&gt;NH₂+H₂O exhibited stronger depletion capabilities. A sensitivity analysis revealed that CH₃+HO₂&lt;=&gt;OH+CH₃O was the main reaction that triggered the temperature rise and radical generation. PO₂+CH₃&lt;=&gt;CH₃PO₂ is an important reaction pathway for CH₃ consumption. These findings provide critical insights for improving LPG safety and designing advanced explosion suppression materials.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114351"},"PeriodicalIF":5.8,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144672485","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":"Laminar burning velocities of ultra-lean iso-octane flames at atmospheric pressure: A comparative study with n-heptane flames","authors":"Xinlu Han ,&nbsp;Kaidi Wan ,&nbsp;Maoqi Lu ,&nbsp;Dingkun Yuan ,&nbsp;Zhongqian Ling","doi":"10.1016/j.combustflame.2025.114358","DOIUrl":"10.1016/j.combustflame.2025.114358","url":null,"abstract":"&lt;div&gt;&lt;div&gt;In this study, the laminar burning velocity, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, of iso-octane, a key gasoline surrogate component, was measured at 298 K and 1 atm using the heat flux method, and comparative analyses were also conducted with the results of n-heptane flames from previous investigation. The experimental conditions covered ultra-lean conditions with an equivalence ratio as low as 0.5 that have never been reported before for the iso-octane flames, which was achieved through H&lt;sub&gt;2&lt;/sub&gt; and O&lt;sub&gt;2&lt;/sub&gt; enrichment. Similar to other fuels tested in earlier studies, a perfect linear relationship was found between &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ln&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mi&gt;u&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;X&lt;/mi&gt;&lt;mi&gt;u&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; being the sum of mole fraction of fuel+oxygen in the unburnt mixture). This relationship was used to extrapolate or interpolate data under conditions that were unmeasurable due to the pulsating instabilities of the ultra-lean iso-octane flames, similar to the ultra-lean n-heptane flames, with carefully evaluated uncertainty. These results, together with a separate set of present measured iso-octane+air flame data with various equivalence ratios at 1 atm and 298 K, were compared with all available literature datasets, among which several more reliable sets were found more consistent and reliable for mechanism validation. Simulations were carried out using three literature models and an updated model from the authors, named Han. A &lt;span&gt;&lt;math&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; function was employed to quantitatively assess the standard deviation of the simulation results from experimental data using each model. The conditions of ultra-lean iso-octane, ultra-lean n-heptane, as well as iso-octane+air and n-heptane+air with large equivalence ratio spans were found with similar orders of the &lt;span&gt;&lt;math&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; function values from the four models. These findings, together with the similar instability performances of the ultra-lean n-heptane and iso-octane flames, were analyzed in terms of global flame characteristics and reaction sensitivities. It was interesting to find that, regardless of whether the conditions were ultra-lean and dominated by H&lt;sub&gt;2&lt;/sub&gt;/C1 reactions or fuel-rich where &gt;C1 reactions became more important, the sensitivity values of laminar burning velocities for each reaction in iso-octane and n-heptane flames were nearly identical. Besides this understanding of the intrinsic physio-chemical nature of the flames, the updated Han model is found with the lowest &lt;span&gt;&lt;math&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; function values for all the conditions discussed in the present study, though with a compact size of 106 species and 508 reaction (74 species and 314 reactions if removing the nitrogen chemistry), which could help th","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"280 ","pages":"Article 114358"},"PeriodicalIF":5.8,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144672483","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}