Combustion and Flame最新文献_第6页

A temporally-resolved investigation on energy deposition from laser-induced plasmas in combustion environments: II. The combined effect of laser field and gas temperature in the post-breakdown region 燃烧环境中激光诱导等离子体能量沉积的暂时解决研究：II。击穿后区域激光场和气体温度的联合效应

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-29 DOI: 10.1016/j.combustflame.2025.114659

Shu Chai , Haimeng Peng , Aochen Li , Ziqing Zhao , Wendong Wu

A series of combustion diagnostic techniques based on laser-induced plasmas (LIP) have been developed recently. Their successful application relies on the understanding of energy deposition behaviors during the LIP excitation process. In our previous work, an approach to monitor the energy deposition behaviors with a temporal resolution of 0.1 ns was developed. In this work, the energy deposition behaviors in the post-breakdown region were further investigated over a range of gas temperature, laser energy, and focusing geometry. The total deposited energy was found to be lower for shorter focal lengths under high temperature, even though the energy fluences in the focal region were higher, which was in contradiction with the observation under room temperature. The temporally resolved analysis indicated that, the instantaneous absorption efficiency quickly climbed after the breakdown was initiated, and then reached a transition point where the slope of instantaneous absorption efficiency changed significantly. Under high temperatures, the transition point was reached earlier while the instantaneous absorption efficiency at this point was much lower for shorter focal lengths, which led to the reduction of total deposited energy. The fast plasma imaging during the laser action time and the analysis of laser field suggested that such behavior is a combined effect of laser field structure and reduced gas density. Under 298 K, the plasmas under different focal lengths were all initiated within the Rayleigh length, and expanded uni-directionally towards the incident direction of laser. Under 1900 K, the plasmas with 75 mm focal length demonstrated a two-lobe structure similar to the structure of laser field, featuring a narrowly ionized center near the focal point. While with 200 mm focal length, the plasma stretched along the larger Rayleigh length on the incident side of focal point. The optical depth of this long plasma led to a higher overall absorption efficiency than that for the two-lobe plasma formed with a short focal length. On the basis of this systematic study, an optimization strategy on the laser energy and focal length can be formed, which can serve as a guideline for the implementation of recently developed LIP-based thermometry methods.

近年来发展了一系列基于激光诱导等离子体（LIP）的燃烧诊断技术。它们的成功应用依赖于对LIP激发过程中能量沉积行为的理解。在我们之前的工作中，我们开发了一种监测能量沉积行为的方法，其时间分辨率为0.1 ns。在这项工作中，进一步研究了在气体温度，激光能量和聚焦几何形状范围内击穿后区域的能量沉积行为。在高温条件下，焦段越短，沉积的总能量越低，而焦段区域的能量影响越大，这与室温条件下的观察结果相矛盾。时间分辨分析表明，瞬时吸收效率在击穿开始后迅速攀升，然后到达瞬时吸收效率斜率发生显著变化的过渡点。在高温下，由于焦距较短，过渡点到达时间较早，瞬时吸收效率较低，导致总沉积能量减少。激光作用时间内的快速等离子体成像和激光场分析表明，这种行为是激光场结构和气体密度降低的共同作用。在298 K下，不同焦距下的等离子体均在瑞利长度内起始，并向激光入射方向单向扩展。在1900 K下，焦距为75 mm的等离子体呈现出与激光场结构相似的双瓣结构，在焦点附近有一个狭窄的电离中心。当焦距为200mm时，等离子体在焦点入射侧沿较大的瑞利长度方向拉伸。这种长等离子体的光学深度导致了比短焦距形成的双瓣等离子体更高的总吸收效率。在此系统研究的基础上，形成了激光能量和焦距的优化策略，可为最近发展的基于lip的测温方法的实施提供指导。

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引用次数: 0

A novel ignition model for low velocity impact of heterogeneous explosives based on interacting hot spots 基于相互作用热点的非均质炸药低速冲击点火模型

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-28 DOI: 10.1016/j.combustflame.2025.114669

Alan Long, Xia Ma, Nikolai Petsev, Brad Clements

While numerous studies have focused on the ignition of explosives occurring in high velocity impact and the associated shock-to-detonation transition, there has been growing interest in developing computational models focused on low-velocity impact regimes. A predictive low-velocity impact ignition model will be important for analyzing high explosive safety and potential accident scenarios. This work introduces a novel ignition model based on the concept of thermally interacting hot spots to simulate low velocity impacted heterogeneous explosives where observed ignition times are on the order of milliseconds. The model asserts that relevant hot spots are micron-sized, the typical separation between neighboring hot spots is on the order of a hundred microns, and that neighbors interact thermally through heat conduction across the interstitial region between them. To achieve tractable numerical solutions, hot spots are assumed to form a periodic array as opposed to the highly irregular positioning in an actual explosive. This idealization allows a single two hotspot system to characterize the ignition process. Consequently, the model is referred to as the two hot spot Frank-Kamenetskii ignition model. In the present study, hot spots are modeled as constant heat sources terms, but this can be extended to include grain-scale phenomena like frictional heating of micron-sized growing cracks that are confined under high pressure. Because the micron-sized features are below the scale that can be efficiently resolved at a systems level, an efficient subscale scheme based on the Method of Weighted Residuals (MWR) is used to efficiently solve the equations. We carry out numerical examples and analytic predictions illustrating the accuracy and the functioning of the model.

虽然许多研究都集中在高速撞击中爆炸物的点火以及相关的冲击到爆轰过渡，但人们对开发低速撞击系统的计算模型越来越感兴趣。预测低速碰撞点火模型对于分析高爆安全性和潜在事故情景具有重要意义。本文介绍了一种基于热相互作用热点概念的新型点火模型，用于模拟低速撞击非均质炸药的点火时间在毫秒量级。该模型认为，相关热点的尺寸为微米级，相邻热点之间的典型距离约为100微米，相邻热点之间通过间隙区域的热传导进行热相互作用。为了获得易于处理的数值解，假定热点形成周期性阵列，而不是在实际爆炸中高度不规则的定位。这种理想化允许一个单一的两个热点系统来表征点火过程。因此，该模型被称为两热点弗兰克-卡梅涅茨基点火模型。在本研究中，热点被建模为恒定热源项，但这可以扩展到包括晶粒级现象，如微米级生长裂纹在高压下的摩擦加热。由于微米级特征在系统层面无法有效求解，采用基于加权残差法的有效子尺度方案对方程进行有效求解。我们进行了数值算例和分析预测，说明了模型的准确性和功能。

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引用次数: 0

Concentration-dependent flame structure in aluminum–methane/air Bunsen flames: A high-fidelity numerical study 铝-甲烷/空气本生火焰的浓度依赖性火焰结构：高保真度数值研究

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-28 DOI: 10.1016/j.combustflame.2025.114664

Fan Zhou , Haiou Wang , Jiarui Zhang , Yongnan Liu , Liya Huang , Kun Luo , Jianren Fan

<div><div>Aluminum particles have emerged as a promising high-energy-density carrier for storing and transporting renewable energy in a future carbon-neutral society. In the present work, high-fidelity numerical simulations of aluminum–methane/air Bunsen flames were performed to investigate the effect of aluminum particle concentration on the gaseous and particle combustion characteristics. Different flame structures were observed as the aluminum particle concentration increases, particularly for the distributions of heat release rate and gaseous temperature fields. In the case with low aluminum particle concentrations (25 g/m<sup>3</sup>), the flame exhibits a characteristic dual-layer configuration: an inner conical zone dominated by intense methane combustion, surrounded by a weaker outer region sustained by aluminum vapor oxidation. When the particle concentration exceeds 300 g/m<sup>3</sup>, aluminum vapor combustion became predominant, establishing a distinctive downstream reaction zone where the primary heat release rate originated from the Al<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O <span><math><mo>=</mo></math></span> AlO ＋ Al (R4) pathway. Notably, at the highest concentration of 550 g/m<sup>3</sup>, the outer flame exhibited substantial intensification with Al<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> <span><math><mo>=</mo></math></span> Al<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O ＋ O (R9) emerging as the dominant exothermic reaction. Particle trajectory analysis revealed spatial heterogeneity in the oxidation dynamics of particles, which is contingent upon their injection positions. To quantitatively assess the completeness of particle combustion, a reaction progress variable was established. In the case with low particle concentration, most particles are completely oxidized due to abundant oxidizers, with comparable contributions from <span><math><msub><mrow><mtext>O</mtext></mrow><mrow><mn>2</mn></mrow></msub></math></span>, H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O and CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> in heterogeneous reactions. In the case with high particle concentration, most particles remain only partially oxidized due to the insufficient oxidizer. However, due to the supply of oxygen in the coflow and the high temperature of the outer flame, particles near the edge of the nozzle undergo intensive reactions. These findings improve our understanding of aluminum–methane/air combustion, which is critical for the optimization of practical propulsion and energy utilization systems.</div><div><strong>Novelty and Significance Statement</strong></div><div>This study provides the first comprehensive investigation of the combustion in aluminum–methane/air Bunsen flames using numeric

在未来的碳中和社会中，铝颗粒已成为一种有前途的高能量密度载体，用于储存和运输可再生能源。本文对铝-甲烷/空气本生火焰进行了高保真数值模拟，研究了铝颗粒浓度对气体和颗粒燃烧特性的影响。随着铝颗粒浓度的增加，火焰结构发生了变化，特别是热释放率和气体温度场的分布发生了变化。在低铝颗粒浓度（25 g/m3）的情况下，火焰呈现出典型的双层结构：内部的圆锥形区域以强烈的甲烷燃烧为主，周围的外部区域由铝蒸气氧化维持。当颗粒浓度超过300 g/m3时，以铝蒸气燃烧为主，形成明显的下游反应区，主要放热速率来源于Al2O = AlO + Al （R4）途径。值得注意的是，在最高浓度为550 g/m3时，外火焰表现出明显的强化，Al2O2 = Al2O + O （R9）成为主要的放热反应。粒子轨迹分析揭示了粒子氧化动力学的空间异质性，这取决于它们的注入位置。为了定量评价颗粒燃烧的完全性，建立了反应过程变量。在颗粒浓度较低的情况下，由于氧化剂丰富，大多数颗粒被完全氧化，O2、H2O和CO2在非均相反应中的贡献相当。在高颗粒浓度的情况下，由于氧化剂不足，大多数颗粒仅部分氧化。然而，由于共流中的氧气供应和外火焰的高温，靠近喷嘴边缘的颗粒发生强烈的反应。这些发现提高了我们对铝-甲烷/空气燃烧的理解，这对实际推进和能源利用系统的优化至关重要。新颖性和意义声明本研究首次使用数值模拟方法对铝-甲烷/空气本生灯火焰的燃烧进行了全面研究。考察了铝颗粒浓度对反应区结构和颗粒燃烧特性的影响。该研究在揭示影响反应区结构的主要元素反应和研究颗粒燃烧特性方面具有新颖之处。这一发现极大地促进了对铝-甲烷/空气燃烧系统的理解，为优化航空航天推进和能源应用的能源效率和稳定性提供了实用的见解。

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引用次数: 0

Modeling CO in large eddy simulations of premixed turbulent jet flames with flame-wall interactions 具有火焰-壁面相互作用的预混湍流射流火焰大涡模拟中CO的建模

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-26 DOI: 10.1016/j.combustflame.2025.114655

Kai Niemietz, Michael Gauding, Heinz Pitsch

The oxidation of carbon monoxide (CO) typically occurs on much longer timescales than the main combustion process, which makes CO emissions difficult to predict with reduced order models. The CO chemistry is further complicated by interactions with turbulence and with cold walls. In this study, a novel model is implemented, which considers both turbulence-chemistry interaction (TCI) and flame-wall interaction (FWI) within the same parameter set to accurately model CO in turbulent, wall-bounded flows. The model is evaluated in large eddy simulations (LES) of premixed turbulent methane/air flames with FWI and validated with data from a direct numerical simulation (DNS) of the same configuration. The combustion model is a flamelet model with tabulated chemistry, compiled from detailed chemistry calculations of 1D flames. In the LES, the necessary quantities are retrieved from the chemistry table via three control variables: the combustion progress variable, an enthalpy defect term to account for wall heat loss, and a flamelet index to consider turbulent strain. The turbulent strain is included by tabulating strained counterflow flamelets and the enthalpy levels are varied by changing the unburnt temperature of the flamelets. Additionally, a transport equation for CO is solved to model transport effects not included in the table. The results show that the tabulated chemistry model is able to accurately reproduce global flame properties such as flame length and fuel flux, if both the wall heat loss and the turbulent strain are considered in the model. In order to predict CO correctly, the additional CO transport equation is necessary.

Novelty and significance statement

This paper presents a novel model for the prediction of CO in turbulent premixed combustion and the a posteriori evaluation in LES. To the authors knowledge, this is the first model to consider the combined effects of flame-wall interactions and turbulent strain on CO. The model is evaluated in turbulent jet flames in the thin reaction zones regime with a relatively high Karlovitz number. In contrast to many investigations of FWI, the simulations were performed with elevated pressure and temperature.

一氧化碳（CO）的氧化通常发生在比主要燃烧过程更长的时间尺度上，这使得CO排放难以用降阶模型预测。CO的化学性质由于与湍流和冷壁的相互作用而进一步复杂化。在本研究中，实现了一种新的模型，该模型考虑了湍流-化学相互作用（TCI）和火焰-壁面相互作用（FWI）在同一参数集内，以准确地模拟湍流壁面流动中的CO。该模型在FWI预混甲烷/空气湍流火焰的大涡模拟（LES）中进行了评估，并使用相同配置的直接数值模拟（DNS）数据进行了验证。燃烧模型是一个化学表的小火焰模型，由一维火焰的详细化学计算编制而成。在LES中，通过三个控制变量从化学表中检索必要的量：燃烧过程变量，考虑壁面热损失的焓缺陷项和考虑湍流应变的火焰指数。紊流应变由应变逆流小片制表，焓值随小片未燃烧温度的变化而变化。此外，还求解了CO的输运方程，以模拟表中未包括的输运效应。结果表明，在考虑壁面热损失和湍流应变的情况下，表化化学模型能够准确地再现火焰长度和燃料通量等整体火焰特性。为了正确地预测CO，额外的CO输运方程是必要的。本文提出了一种新的湍流预混燃烧中CO的预测模型和LES的后验评价模型。据作者所知，这是第一个考虑火焰壁相互作用和湍流应变对CO的综合影响的模型。该模型在具有相对较高Karlovitz数的薄反应区湍流射流火焰中进行了评估。与FWI的许多研究不同，本次模拟是在高压和高温下进行的。

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引用次数: 0

Extinction characteristics of laminar bluff body flames in a transverse direct current electric field 横向直流电场中层流钝体火焰的消光特性

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-26 DOI: 10.1016/j.combustflame.2025.114665

Bowen Liu , Jianling Li , Yunke Wu , Hao Zhao

The effect of the transverse direct current (DC) electric field on bluff body flames was investigated across four flame morphologies, such as attachment, partial attachment, lifting, and blow out in experiments by using a CH₄/O₂/N₂ mixture with equivalence ratios (ϕ) ranging from 0.55 to 0.90 at a constant flow velocity (V = 1 m/s). The high-intensity transverse DC electric field accelerated the transition between flame morphologies, from attachment to partial attachment, then to lifting, and finally to blow out (extinction), primarily due to the effect of ionic wind. Further, the extinction induced by the transverse DC electric field was explored in terms of the flame instability by using a CH₄/O₂/CO₂/N₂ mixture with different Lewis numbers (Le). Under a transverse DC electric field with a bias voltage of 4 kV, visible flame distortions caused by thermal diffusive instabilities were observed in the CH₄/O₂/CO₂/N₂ mixture at ϕ = 0.55, V = 1 m/s, and Le ≈ 1.0, which were not observed without the electric field. Meanwhile, the bias voltage required for extinguishing bluff body flames decreased at a larger blending ratio of CO₂ or a lower Lewis number. The results indicated that the transverse DC field led to an early flame extinction through both the ionic wind effects and exacerbated thermal diffusive instability.

采用等速（V = 1 m/s）条件下，采用等速（φ）为0.55 ~ 0.90的CH4/O2/N2混合物，研究了横向直流电场对断续体火焰在附着、部分附着、提升和熄灭四种火焰形态下的影响。高强度横向直流电场加速了火焰形态之间的转变，从附着到部分附着，再到提升，最后到熄灭（熄灭），这主要是由于离子风的作用。此外，利用不同路易斯数（Le）的CH4/O2/CO2/N2混合物，从火焰不稳定性的角度探讨了横向直流电场引起的消光。在偏置电压为4 kV的横向直流电场作用下，CH4/O2/CO2/N2混合物在φ = 0.55, V = 1 m/s, Le≈1.0时，由于热扩散不稳定性引起的火焰畸变明显可见，而没有电场作用时则没有。同时，随着CO2掺量的增大和Lewis数的减小，熄灭钝体火焰所需的偏置电压降低。结果表明，横向直流电场通过离子风效应导致火焰提前熄灭，并加剧了热扩散不稳定性。

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引用次数: 0

Machine learning-assisted analysis of ignition and combustion properties in as-milled and annealed Al-Zr composite powders 机器学习辅助分析Al-Zr复合粉末的烧结和退火着火和燃烧特性

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-25 DOI: 10.1016/j.combustflame.2025.114660

Michael R. Flickinger , Sreenivas Raguraman , Amee L. Polk , Colin Goodman , Megan Bokhoor , Rami Knio , Michael Kruppa , Mark A. Foster , Timothy P. Weihs

Micron-scale metal-based composite powders are promising for energetic applications due to their tailored ignition and combustion properties. In particular, ball-milled Al/Zr composites exhibit lower ignition thresholds than pure aluminum, driven by exothermic intermetallic formation reactions and have demonstrated enhanced combustion properties. However, the extent to which this heat release governs ignition and combustion remains unclear, especially when progressively removed through annealing. To systematically investigate this effect, we synthesized Al/Zr powders (3Al:Zr, Al:Zr, and Al:3Zr) via ball milling, annealed them in argon up to 1000 °

C

to partially complete the formation reactions, and characterized their ignition and combustion behavior. Ignition thresholds were measured using a hot wire method across different environments, while high-speed hyperspectral imaging tracked single-particle burn durations and temperatures. A machine-learning approach utilizing convolutional neural networks (CNNs) was developed to quantify the frequency of microexplosions. Results show that annealing – and thus reducing available reaction heat – increases ignition thresholds, most significantly for Al-rich compositions. In contrast, Zr-rich powders exhibit little change in ignition thresholds due to oxidation aiding ignition. Despite removing the available heat that drives ignition, average combustion temperatures range from 2400 K to 3000 K and increased with annealing for Al- and Zr-rich powders. Average maximum temperatures are 100 to 400 K higher. The frequency of microexplosions remains high (

>

46%) and increases with annealing for all but the Al-rich powders. These findings suggest that while homogeneous Al/Zr powders (e.g., atomized) may exhibit higher ignition thresholds, they can achieve comparable combustion performance once ignited.

Novelty and Significance Statement

While previous studies have explored how powder chemistry and milling conditions affect the ignition behavior of ball-milled composites, none have directly examined how removing exothermic heat from intermixing and formation reactions influences ignition thresholds and combustion behavior. This is the first study to investigate multiple Al/Zr stoichiometries in ball-milled composite powders that were annealed to form pre-existing intermetallics, and to evaluate how this controlled intermetallic formation affects combustion performance by comparing as-milled and annealed powders at each stoichiometry. Microexplosion frequency of single particles was quantified using a novel convolutional neural network pipeline; to our knowledge, this is the first application of deep learning to quantify microexplosions in single-particle or plume experiments.

微米级金属基复合粉末由于其定制的点火和燃烧性能，在高能应用中前景广阔。特别是，在放热金属间形成反应的驱动下，球磨Al/Zr复合材料表现出比纯铝更低的着火阈值，并表现出增强的燃烧性能。然而，这种热量释放对点火和燃烧的影响程度仍不清楚，特别是当通过退火逐渐去除时。为了系统地研究这种影响，我们通过球磨合成了Al/Zr粉末（3Al:Zr， Al:Zr和Al:3Zr），在氩气中退火至1000℃，部分完成了形成反应，并表征了它们的点火和燃烧行为。在不同的环境下，使用热丝法测量点火阈值，而高速高光谱成像跟踪单颗粒燃烧持续时间和温度。利用卷积神经网络（cnn）开发了一种机器学习方法来量化微爆炸的频率。结果表明，退火-从而降低了可用的反应热-增加了点火阈值，最显著的是富铝成分。相比之下，富锆粉末由于氧化助燃，其着火阈值变化不大。尽管去除了驱动点火的可用热量，但对于富Al和富zr粉末，平均燃烧温度范围从2400 K到3000 K，并且随着退火而升高。平均最高温度高出100至400k。微爆炸的频率仍然很高（46%），并且随着退火的增加而增加，但富铝粉末除外。这些发现表明，虽然均相Al/Zr粉末（例如，雾化）可能表现出更高的点火阈值，但一旦点燃，它们可以达到相当的燃烧性能。虽然以前的研究已经探索了粉末化学和铣磨条件如何影响球磨复合材料的点火行为，但没有人直接研究从混合和形成反应中去除放热如何影响点火阈值和燃烧行为。这是第一个研究退火形成预先存在的金属间化合物的球磨复合粉末中多种Al/Zr化学计量的研究，并通过比较每种化学计量的研磨和退火粉末来评估这种受控的金属间化合物形成如何影响燃烧性能。采用一种新颖的卷积神经网络管道对单个颗粒的微爆炸频率进行了量化；据我们所知，这是深度学习在单粒子或羽流实验中首次应用于量化微爆炸。

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引用次数: 0

Investigation of kinetic inhibition effectiveness and mechanisms of HCFO-1233xf as a new fire extinguishing agent 新型灭火剂HCFO-1233xf的动力学抑制效果及机理研究

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-25 DOI: 10.1016/j.combustflame.2025.114663

Xingyu Wang , Xiao Zhang , Peiyao Chen

The search for viable chemical fire suppressants in civil aviation persists, as current candidates are limited by high toxicity, low efficiency, or high boiling points. This study experimentally investigates the suppression effects of HCFO-1233xf (2‑chloro-3,3,3-trifluoropropene, abbreviated as XF) on methane-air and propane-air premixed flames under ambient conditions. Results demonstrate that XF exhibits 30 % and 38 % higher mass-based suppression efficiency than R125 (CF₃CHF₂) and R227ea (CF₃CHFCF₃) in stoichiometric flames, respectively. A kinetic model was developed to reveal the inhibition mechanism of the superior chemical kinetic efficiency of XF under stoichiometric and fuel-rich conditions. Simulation results suggest that the double bond in XF enhances its reactivity, likely enabling rapid decomposition to generate Cl and CF₃ radicals, which are effective in slowing combustion chain reactions. This mechanism is consistent with the observed simulation data, where the chemical inhibition effect of XF is approximately 1.5 times greater than that of R125 and R123 and twice that of R227ea. Normalized burning velocity calculations for methane-air flames indicate the mass-based inhibition parameter for XF ranks highest among known halon alternatives, surpassed only by brominated compounds.

寻找民用航空中可行的化学灭火剂的工作仍在继续，因为目前的候选材料受到高毒性、低效率或高沸点的限制。实验研究了HCFO-1233xf（2 -氯-3,3,3-三氟丙烯，简称XF）在常温条件下对甲烷-空气和丙烷-空气预混火焰的抑制作用。结果表明，在化学计量火焰中，XF的质量抑制效率比R125 （CF3CHF2）和R227ea （CF3CHFCF3）分别高出30%和38%。建立了动力学模型，揭示了XF在化学计量和富燃料条件下优异的化学动力学效率的抑制机理。模拟结果表明，XF中的双键增强了其反应活性，可能使其快速分解产生Cl和CF3自由基，这对减缓燃烧链反应是有效的。这一机理与观察到的模拟数据一致，XF的化学抑制作用约为R125和R123的1.5倍，是R227ea的2倍。甲烷-空气火焰的标准化燃烧速度计算表明，XF的基于质量的抑制参数在已知的哈龙替代品中排名最高，仅次于溴化化合物。

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引用次数: 0

Electrically Initiated Ammonium Perchlorate Based Gel Propellants with Varying Electrode Geometry 电引发的高氯酸铵基凝胶推进剂具有不同的电极几何形状

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-25 DOI: 10.1016/j.combustflame.2025.114661

Nicholas Fiorenza, Wei-Che Lin, Gregory Young

An experimental study exploring the ignition behavior of an electrically initiated gel monopropellant composed of an ionically conducting liquid polymer (polyethylene glycol) and ammonium perchlorate (AP) was conducted. Complexation of AP with PEG enabled ion transport when a voltage was applied resulting in ignition. Although the propellant was manufactured by solution casting, the final product contained no solvent as confirmed by thermogravimetric analysis. Several electrode configurations were explored which balanced or limited either oxidation or reduction at the electrodes. Other than when reduction was limited, ignition always occurred at the anode. Limiting reduction resulted in an apparent increase in the bulk resistivity of the propellant which was attributed to enhanced bubble/gas formation at the cathode. The increase in apparent bulk resistivity resulted in enhanced joule heating and a shift in ignition mechanism from predominately electrochemical to thermal. This behavior is supported by analysis of the current data and infrared temperature measurements. The temperature measurements demonstrate that the highest pre-ignition temperatures occur in close proximity to where the processes are limited.

对由离子导电液体聚合物（聚乙二醇）和高氯酸铵（AP）组成的电引发凝胶单推进剂的点火行为进行了实验研究。当施加电压导致点火时，AP与PEG的络合使离子传输成为可能。虽然推进剂是通过溶液铸造制造的，但经热重分析证实，最终产品不含溶剂。探索了几种平衡或限制电极氧化或还原的电极结构。除了还原受到限制外，着火总是发生在阳极。极限还原导致推进剂体积电阻率的明显增加，这归因于阴极处气泡/气体形成的增强。视体电阻率的增加导致焦耳加热的增强和点火机制从主要的电化学转变为热。对当前数据和红外温度测量的分析支持了这种行为。温度测量表明，最高的预点火温度发生在接近工艺限制的地方。

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引用次数: 0

Elucidating norbornane auto-ignition behavior via RCM experiments and kinetic modelling 通过RCM实验和动力学模型阐明降冰片烯的自燃行为

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-25 DOI: 10.1016/j.combustflame.2025.114656

Hang Xiao, Zhaohan Chu, Chenyue Tao, Xiao Liu, Bin Yang

Norbornane (C₇H₁₂), a typical polycyclic alkane, is currently of interest as a backbone for next-staged aviation fuels in fuel design and as a potential additive in commercial fuel to improve combustion performance. The polycyclic geometry of norbornane poses challenges in the characterization of its kinetics, thus hindering future applications. In this work, a combined experimental and kinetic modeling approach was employed to study the auto-ignition behavior of norbornane. A set of norbornane auto-ignition experiments was conducted in a rapid compression machine, covering the equivalence ratios of 0.5 and 1.0 across the temperature range of 623 K to 923 K and pressures of 10, 15, and 20 bar. The auto-ignition process of norbornane exhibits the two-stage ignition behavior. Ignition delay times were recorded, showing the negative temperature coefficient (NTC) phenomenon. With the assistance of gas chromatography, several oxidation products were identified and their concentration profiles through the whole ignition process were obtained under a typical condition, also demonstrating obvious two-stage ignition behavior. The first detailed oxidation kinetic model of norbornane was built with 939 species and 4364 reactions. Simulation results exhibit consistent agreement with experimental data. Throughout the modeling analyses, the critical reactions governing the ignition process are uncovered to elucidate the 2-staged ignition behavior. The increase of the effective temperature (T_eff) shifts the branching ratio of low-temperature oxidation pathways, accounting for the disappearance of first-stage ignition and inducing the emergence of the NTC phenomenon of global ignition. Also, the different pressure dependencies of the first-stage and the global ignition contribute to the pressure effect on the shift of the temperature region showing the NTC.

Norbornane （C7H12）是一种典型的多环烷烃，目前作为下一阶段航空燃料的骨干燃料设计和潜在的商业燃料添加剂，以改善燃烧性能。降冰片烷的多环几何结构给其动力学表征带来了挑战，从而阻碍了其未来的应用。本文采用实验与动力学相结合的方法对降冰片烯的自燃行为进行了研究。在快速压缩机上进行了一组降硼醚自燃实验，实验温度为623 K ~ 923 K，压力为10、15、20 bar，当量比为0.5和1.0。降冰片烯的自燃过程表现为两段点火行为。记录了点火延迟时间，显示了负温度系数（NTC）现象。在气相色谱法的辅助下，鉴定了几种氧化产物，并在典型条件下得到了它们在整个点火过程中的浓度分布，也表现出明显的两段点火行为。建立了含939种物质和4364种反应的降冰片烷氧化动力学模型。仿真结果与实验数据吻合较好。在整个模型分析中，揭示了控制点火过程的关键反应，以阐明两段点火行为。有效温度（Teff）的增加改变了低温氧化途径的分支比例，导致了第一级点火的消失，并诱发了全局点火NTC现象的出现。此外，第一级和全局点火的不同压力依赖关系也有助于压力对显示NTC的温度区域移动的影响。

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引用次数: 0

Precision thermometry of flat flames using spatially resolved multi-color laser absorption spectroscopy of carbon dioxide 利用空间分辨二氧化碳多色激光吸收光谱对扁平火焰进行精确测温

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame

Pub Date : 2025-11-24 DOI: 10.1016/j.combustflame.2025.114649

Shuoxun Zhang, Shengkai Wang

<div><div>This work developed an accurate and robust absorption-based method for spatially resolved measurements of gas temperatures in flames and reacting flows, with typical single-measurement uncertainties on the order of 1%. This method exploits narrow-linewidth laser absorption of hot CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> molecules, which can be generated from combustion or artificially seeded into the flow. A collinear dual-laser setup allowed for periodic scans over tens of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> absorption transitions near the <span><math><msub><mrow><mi>ν</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> bandhead every <span><math><mrow><mn>100</mn><mspace></mspace><mi>μ</mi><mi>s</mi></mrow></math></span>, from which the gas temperature (as well as CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> concentrations) was determined with high sensitivity and robustness. Spatially resolved measurements were achieved using an electrically driven high-speed beam scanning system consisting of a 2-D galvo scanner and a pair of off-axis parabolic mirrors. An effective spatial resolution of 1 mm was achieved at a planar field measurement speed of 200 Hz and a volumetric field measurement speed of 2 Hz. A physically constrained nonlinear inference framework was also developed for the quantitative analysis of the measurement data. Proof-of-concept experiments were performed on axisymmetric flames stabilized on a Mckenna burner at various equivalence ratios and flow rates, and the results agreed asymptotically with the theoretical value of the adiabatic flame temperature. An additional experiment on a flame of complex geometry demonstrated an excellent level of resolution, precision, and contrast achieved by the current thermometry method. This method promises to provide good utility in future combustion studies due to its high performance metrics and relative ease of use.</div><div><strong>Novelty and Significance</strong></div><div>This study presented, to the authors’ knowledge, the first absorption-based spatially resolved flame thermometry method that achieved a typical single-shot measurement accuracy on the order of 1%. This method exploited a unique dual-laser setup that allowed rapid scanning over tens of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> transitions with drastically different temperature sensitivity, thereby ensuring high measurement sensitivity, accuracy, and robustness. Spatially resolved measurements were achieved using an electrically driven high-speed 2D beam scanning system, with an effective spatial resolution of 1 mm at a planar field measurement speed of 200 Hz and a volumetric field measurement speed of 2 Hz. The performance of this method was thoroughly validated in a series of proof-of-concept experiments. This method is anticipated to be widely adopted in fut

这项工作开发了一种准确而稳健的基于吸收的方法，用于火焰和反应流中气体温度的空间分辨测量，典型的单次测量不确定度约为1%。这种方法利用窄线宽激光吸收热CO2分子，这些分子可以由燃烧产生，也可以人为地注入气流中。共线双激光装置允许每100μs对ν3波段附近的数十次CO2吸收跃迁进行周期性扫描，从中确定气体温度（以及CO2浓度）具有高灵敏度和鲁棒性。空间分辨测量是通过电驱动的高速光束扫描系统实现的，该系统由一个二维电激扫描仪和一对离轴抛物面镜组成。当平面场测量速度为200 Hz，体场测量速度为2 Hz时，有效空间分辨率为1 mm。为对测量数据进行定量分析，建立了物理约束非线性推理框架。在麦肯纳燃烧器上进行了轴对称火焰在不同当量比和流量下的概念验证实验，结果与绝热火焰温度的理论值渐近一致。在复杂几何形状的火焰上进行的另一个实验表明，当前的测温方法具有出色的分辨率、精度和对比度。该方法由于其高性能指标和相对易于使用，有望在未来的燃烧研究中提供良好的效用。据作者所知，本研究提出了第一个基于吸收的空间分辨火焰测温方法，该方法实现了典型的单次测量精度在1%左右。该方法利用独特的双激光装置，可以快速扫描数十种不同温度灵敏度的CO2跃迁，从而确保高测量灵敏度、精度和鲁棒性。利用电驱动的高速二维波束扫描系统实现了空间分辨率的测量，在200 Hz的平面场测量速度和2 Hz的体积场测量速度下，有效空间分辨率为1 mm。该方法的性能在一系列的概念验证实验中得到了充分的验证。由于该方法具有较高的性能指标和相对易于使用，因此有望在未来的燃烧研究中得到广泛采用。

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引用次数: 0