Combustion and Flame最新文献

{"title":"Accurately measuring slowly propagating flame speeds: Application to ammonia/air flames","authors":"Joel Mathew,&nbsp;Justin K. Tavares,&nbsp;Jagannath Jayachandran","doi":"10.1016/j.combustflame.2024.113807","DOIUrl":"10.1016/j.combustflame.2024.113807","url":null,"abstract":"<div><div>Environmental concerns have driven the development of alternative fuels and refrigerant working fluids with low global warming potential. Ammonia (NH₃) is a potential zero-carbon fuel, while hydrofluorocarbons (HFCs) like R-32 and R-1234yf are being adopted as refrigerants. When mixed with air, these compounds can sustain slowly propagating flames with laminar flame speeds less than 10 cm/s. Unlike typical hydrocarbon-fueled flames, these slow flames are influenced by buoyancy-induced flow and radiation heat loss. In this study, we experimentally investigate the flame speeds of NH₃/air mixtures using the constant-pressure spherically expanding flame method, while circumventing gravity-induced natural convection, and account for radiation-induced inward flow. To mitigate buoyant convection, a low-cost drop tower was built and used to study slow spherically expanding flames in free fall. A computational model (SRADIF) is utilized that combines thermodynamic equilibrium and finite rate optically thin limit radiation heat loss calculations to estimate the inward flow. The developed methodology is utilized to investigate slowly propagating NH₃/air flames over a range of equivalence ratios. A systematic approach was undertaken to understand and quantify the errors that could arise when deriving the laminar flame speed. It was found that attempting to study slowly propagating flames in a static configuration, as opposed to in free fall, results in large differences in flame dynamics and subsequently all derived quantities. It is necessary to study slowly propagating flames in free-fall. Additionally, using experimental data that has not been corrected for radiation-induced flow leads to large errors in all derived quantities. Furthermore, direct comparisons of experimental measurements and detailed flame simulations are found to be necessary to determine if existing extrapolation approaches are applicable to these slowly propagating flames, which are challenging to study.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113807"},"PeriodicalIF":5.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593301","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":"Direct combustion noise: Nearfield and non-compactness influences on pressure–heat release coherence","authors":"Sungyoung Ha,&nbsp;Tim Lieuwen","doi":"10.1016/j.combustflame.2024.113811","DOIUrl":"10.1016/j.combustflame.2024.113811","url":null,"abstract":"<div><div>There are several mechanisms through which turbulent flames produce sound. In low Mach number, unconfined flows, direct combustion noise – i.e., unsteady gas expansion generated by heat release fluctuations – is known to be a dominant contributor. This study is motivated by the fact that in the farfield, the coherence between spatially integrated heat release fluctuations from acoustically compact flames and direct combustion noise is unity. This suggests that the role of direct combustion noise relative to other sources can be ascertained from the value of the coherence. However, in practice it is difficult to fully satisfy the requirements to achieve a unity coherence, even in cases where direct combustion noise is the dominant noise source. This paper explores the contribution of noncompactness and nearfield effects on coherence. For the noncompactness part, while it is often the case that flames are small relative to a wavelength, they are never infinitesimally small. For the nearfield aspect, it is often not possible or practical to obtain farfield measurements, particularly in confined environments. This paper presents calculations that quantify how these noncompactness and nearfield effects influence coherence values. These calculations provide guidance on frequency ranges over which direct combustion noise will lead to near-unity coherence values, as well as required distances and optimal angles for acoustic instrumentation.</div><div><strong>Novelty and significance statement</strong></div><div>This study presents a theoretical study on the coherence between heat release rate and acoustic pressure fluctuations, which has been mostly overlooked in prior literature. To the extent of the author’s knowledge, this is the first attempt that identify and investigate the inconsistencies between traditional theory and experimental literature on coherence. Results have implications for our previous understanding of the relationship between the heat release rate fluctuations and direct noise, aiding in future studies on combustion noise.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113811"},"PeriodicalIF":5.8,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587328","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":"Thermal oxidation, ignition, and combustion characterization of AP-, LP-, and KN- coated multi-metal composite powders in Air/H2O environments","authors":"Wenke Zhang ,&nbsp;Peihui Xu ,&nbsp;Daolun Liang ,&nbsp;Jianzhong Liu","doi":"10.1016/j.combustflame.2024.113808","DOIUrl":"10.1016/j.combustflame.2024.113808","url":null,"abstract":"<div><div>Studying the ignition and combustion performances of modified aluminum-based metallic fuels in variable oxidizing atmospheres is highly important for large-scale space exploration. In this study, Al–B–Mg multi-metal composite powders (MMP) were prepared using the mechanical ball-milling method.It was coated respectively by ammonium perchlorate (AP), lithium perchlorate (LP), and potassium nitrate (KN) to obtain modified multi-metal composite powder fuels (AP@MMP, LP@MMP, and KN@MMP, respectively) by a recrystallization method. The samples were characterized and their thermal oxidation, ignition and combustion processes were investigated through a TG and laser-ignition experiment under Air/H₂O environments. The results show that the MMP samples can potentially be called pure aluminum substitutes. All three samples exhibit fast ignition characteristics with ignition delay times of 2.95–6.75 ms in air. AP@MMP exhibits the highest ignition speed. The thermal oxidation, ignition, and combustion properties of all samples decayed with increasing water content in the atmosphere (Air→Air+H₂O→H₂O). AP@MMP exhibits a significantly more intense and stable combustion overall than LP@MMP and KN@MMP. This study expands the direction and application range of aluminum-based composite metal fuels, guiding their applications in Air/H₂O environments.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113808"},"PeriodicalIF":5.8,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587326","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":"Effect of cerium trifluoride on combustion properties of nano-aluminum powder","authors":"Yajun Wang,&nbsp;Wenyu Li,&nbsp;Ruihua Liu,&nbsp;Zhengliang Deng,&nbsp;Qiang Gan","doi":"10.1016/j.combustflame.2024.113831","DOIUrl":"10.1016/j.combustflame.2024.113831","url":null,"abstract":"<div><div>To investigate the influence of cerium trifluoride (CeF₃) on the combustion performance of nano aluminum powder (n-Al), different mass fractions of CeF₃ were physically mixed into the n-Al powder. Research results show that CeF₃ can significantly increase the main exothermic heat of n-Al powder. When the CeF₃ content was 10 %, the heat release reached 9579.90 J·g^‒1. However, as the CeF₃ content increased, the heat release of the sample decreased. Thermal analysis results of Al/CeF₃ and Al/CeO₂ infer that this was due to the action of CeO₂ generated by pre-ignition reaction for Al/CeF₃–15. The presence of CeO₂ inhibited the reaction degree of Al, thereby reducing the heat release. Meanwhile, as the proportion of CeF₃ increased, the peak temperature of the main reaction exothermic peak was delayed, and more energy input was required for the oxidation of n-Al powder. Combustion experiments show that the addition of CeF₃ greatly shortened the combustion time of n-Al powder, with the shortest time being 4.43 s. In addition, due to the excellent storage and release oxygen capability of CeO₂, multiple micro-explosions occurred in the composite material during combustion.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113831"},"PeriodicalIF":5.8,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587329","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":"An experimental, theoretical and kinetic modeling study of the N2O-H2 system: Implications for N2O + H","authors":"Peter Glarborg ,&nbsp;Eva Fabricius-Bjerre ,&nbsp;Tor K. Joensen ,&nbsp;Hamid Hashemi ,&nbsp;Stephen J. Klippenstein","doi":"10.1016/j.combustflame.2024.113810","DOIUrl":"10.1016/j.combustflame.2024.113810","url":null,"abstract":"<div><div>The reaction of N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O with H is the key step in consumption of nitrous oxide in thermal processes. The major product channel is N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> + OH, while NH + NO constitute minor products. In addition, a pathway involving HNNO, initiated by N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O + H (+M) <span><math><mo>⇄</mo></math></span> HNNO (+M) (R3, R4), has been inferred from experiment and theory by Burke and coworkers. At longer reaction times, the reaction may reach partial equilibration, and in addition to k<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> and k<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span> the importance of this channel depends on the thermodynamic properties of HNNO and its consumption reactions, mainly HNNO + H. In the present work, we re-examined the thermochemistry of HNNO and calculated rate constants and branching fractions for the HNNO + H reaction. Experiments on the N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O–H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> system were conducted in a high-pressure flow reactor at 100 atm as a function of temperature (600-925 K) and stoichiometry and explained in terms of an updated chemical kinetic model. The results support the importance of the HNNO pathway, which results in inhibition of N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O consumption and formation of NH<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>. In addition, selected literature results on the N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O–H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> system are re-examined and the implications for the other product channels of N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O + H, in particular NH + NO, are discussed.</div><div><strong>Novelty and significance statement</strong></div><div>This study provides the first detailed kinetic analysis of the N<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O/H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> system at high pressure and intermediate temperatures, based on flow reactor results and high-level theoretical calculations. The experimental conditions augment the importance of a reaction pathway involving HNNO as intermediate. Inclusion in the model of a subset for HNNO, including present calculations for HNNO + H, is crucial for capturing the observed behavior.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113810"},"PeriodicalIF":5.8,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578491","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":"Numerical simulation of flame propagation characteristics of NH3/Air flames assisted by non-equilibrium plasma discharge","authors":"Qi Zhan,&nbsp;Yangyang Ban,&nbsp;Fan Zhang,&nbsp;Yiqiang Pei,&nbsp;Yanzhao An","doi":"10.1016/j.combustflame.2024.113809","DOIUrl":"10.1016/j.combustflame.2024.113809","url":null,"abstract":"<div><div>Nanosecond non-equilibrium plasma-assisted combustion technology emerges as a reliable novel approach to enhance the flame propagation speed of NH₃. In this study, we developed a zero-dimensional + one-dimensional (0-D+1-D) non-equilibrium plasma-assisted combustion model to investigate the impact of nanosecond pulse discharge on the freely propagating flame speed of NH₃/Air mixture. The results reveal that due to the plasma discharge, abundant intermediate species (N₂H₄, N₂H₃, NO, H₂O₂) are formed at the inlet and are subsequently transported downstream, facilitating flame propagation. As a result, the speed of the 1-D freely propagating flame increases, and the flame front is closer to the inlet compared to the non-plasma condition. The transport effect of H₂ is also evident, with high concentrations of H₂ from the inlet providing the basis for reactions at the flame front that promote combustion. Furthermore, after the initial mixture flows into the flame front, a slight increase in heat release is observed, but this increase occurs within a very limited distance. Notably, in the case of plasma, a stronger heat release is evident at the flame front. Moreover, with plasma, the peaks of OH, H, O, NH₂, and HO₂ are higher and earlier than those of the non-plasma case due to the transport and kinetic effects of plasma. Pathway flux analyses reflect significant changes in the production and consumption paths of the three components OH, H, and O, which are most important for consuming NH₃ due to plasma addition. The higher OH mass fraction promotes the chain reactions that consume NH₃, effectively enhancing the flame propagation speed.</div></div><div><h3>Novelty and significance statement</h3><div>This study introduces a novel 0-D+1-D nanosecond non-equilibrium plasma-assisted combustion model to examine the impact of nanosecond pulse discharge on NH₃/Air flame propagation. It uniquely analyzes the interaction between species at the inlet and flame front, highlighting the transport effects of plasma-generated intermediates (N₂H₄, N₂H₃, NO, H₂O₂, H₂) that enhance flame speed, with a detailed pathway analysis of key species (O, OH, H).</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113809"},"PeriodicalIF":5.8,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571919","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":"Dynamic interaction patterns of oblique detonation waves with boundary layers in hypersonic reactive flows","authors":"Jie Sun ,&nbsp;Pengfei Yang ,&nbsp;Zheng Chen","doi":"10.1016/j.combustflame.2024.113832","DOIUrl":"10.1016/j.combustflame.2024.113832","url":null,"abstract":"<div><div>Due to their high thermal cycle efficiency and compact combustor, oblique detonation engines hold great promise for hypersonic propulsion. Previous numerical simulations of oblique detonation waves have predominantly solved the Euler equations, disregarding the influence of viscosity and boundary layers. This work aims to study how the interaction between the oblique detonation wave and the boundary layer influences the detonation wave structures in confined spaces. Two-dimensional numerical simulations considering detailed chemistry are performed in a stoichiometric H₂/air mixture. The results indicate that the wedge-induced oblique detonation wave generates a strong adverse pressure gradient upon impacting the upper wall, leading to boundary layer separation. The separation zone subsequently induces an oblique shock wave near the upper wall, and an increase in separation angle will cause the transition from an oblique shock wave to an oblique detonation wave. The formation of the separation zone reduces the actual flow area and may even lead to flow choking; its obstructive effect is similar to that of the Mach stem in inviscid flow. To establish a connection between the viscous recirculation zone and the inviscid Mach stem, we introduce a dimensionless parameter, <em>η</em>, based on the inviscid assumption. It is defined as the ratio of the inviscid Mach stem height to the channel entrance height. This parameter can be used to identify three wave systems in a viscous flow field: separation shock-dominated wave systems, separation detonation-dominated wave systems, and unstable Mach stem-dominated wave systems. Among these, the appearance of detonation Mach stems leads to flow choking, and the shock-detonation wave system continually moves upstream, ultimately causing the failure of the oblique detonation combustion. The findings of this study provide new insights into the investigation of the influence of viscosity on the flow structure of oblique detonation waves.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113832"},"PeriodicalIF":5.8,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571896","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":"Comparative study on the characteristics of energy release, decomposition, and combustion between NEPE propellants and HTPB propellants","authors":"Hui Liu ,&nbsp;Fang Wang ,&nbsp;Huanhuan Gao ,&nbsp;Yukun Chen ,&nbsp;Xueqin Liao ,&nbsp;Jianzhong Liu","doi":"10.1016/j.combustflame.2024.113827","DOIUrl":"10.1016/j.combustflame.2024.113827","url":null,"abstract":"<div><div>Energy performance is always the primary focus of solid propulsion technology development. This paper investigated the characteristics of the energy release, decomposition, and combustion of two typical propellants (NEPE propellants and HTPB propellants) using NASA-CEA calculations, thermal analysis, and an electric wire ignition combustion system. The decomposition temperature of NG, BTTN, GAP, and CL-20 in NEPE propellants were low. The decomposition products were abundant and the decomposition exotherm was large. It had a strong inhibitory effect on LTD of AP and a strong promotional effect on HTD of AP, resulting in the combination of HTD and LTD of AP into a single peak. The flame brightness of two propellants was obviously improved with pressure increasing, as was the flame expansion area, burning rate, and combustion intensity. The ignition delay time <em>t</em>_i decreased and the burning rate <em>r</em> increased. Compared to HTPB propellants, NEPE propellants had brighter flames, larger flame expansion area, more intense combustion, smaller <em>t</em>_i, and smaller <em>r</em> under the same pressure. The pressure exponent n of NEPE propellants (0.43) was larger than that of HTPB propellants (0.39). The rate of the chemical reactions and the rate of diffusion and mixing had a greater impact on the burning rate of NEPE propellants.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113827"},"PeriodicalIF":5.8,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571921","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":"Theoretical kinetics study of hydrogen abstraction reactions of O2(X3Σg/a1Δg) + CnH2n+2 (n ≤ 4)","authors":"Jie Chen ,&nbsp;Qi Chen ,&nbsp;Nan Liu ,&nbsp;Shanshan Ruan ,&nbsp;Xianwu Jiang ,&nbsp;Lidong Zhang","doi":"10.1016/j.combustflame.2024.113812","DOIUrl":"10.1016/j.combustflame.2024.113812","url":null,"abstract":"<div><div>The chain-initial reactions of small-molecule alkane (C_nH_2n+2(n ≤ 4)) oxidation participated by electronically excited oxygen O₂(a¹Δg) are crucial for understanding the role of O₂(a¹Δ_g) in plasma-assisted combustion and fuel reforming. Accordingly, in the present work, the energy barriers for the reactions O₂(X³Σ_g/a¹Δg) + alkane (n ≤ 4) → products were investigated by using high-precision quantum calculations. Rate constants for each reaction channel within the temperature range of 300–1500 K were predicted based on transition state theory (TST), supplementing plasma kinetics parameters. The energy barriers and rate constants for methane and ethane oxidation dehydrogenation reactions showed good agreement with literature data, validating the accuracy of the computational method employed in this work. The calculations revealed that the dehydrogenation sites have vital impacts on the reaction system. The energy barriers of the reaction channels involved in O₂(a¹Δ_g) were reduced at different dehydrogenation sites. Specifically, the change rate of each reaction energy barrier at primary, secondary and tertiary site was about 40 %, 65 % and 65 %, respectively. The reactions involving O₂(a¹Δ_g) significantly increased the reaction rate coefficient, especially for single hydrogen abstraction at the secondary and tertiary sites. The effect of O₂(a¹Δ_g) on ignition promotion and its regularity were further studied through kinetic simulations. The results suggested that adding O₂(a¹Δ_g) reduces the ignition delay time (IDT) of small molecular alkanes by approximately one order of magnitude, attributed to variations in energy barrier and branching ratios of different reaction channels. Notably, the H-atom abstraction reaction on primary site showed the largest sensitivity in IDT at 800 K, particularly for propane and isobutane, with IDT change rates of 98.0 % and 96.3 %, respectively. This study provided reasonable rate coefficients for kinetic modeling of plasma-assisted alkane ignition.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113812"},"PeriodicalIF":5.8,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571920","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":"Mapping the performance envelope and energy pathways of plasma-assisted ignition across combustion environments","authors":"Raphael J. Dijoud ,&nbsp;Nicholas Laws ,&nbsp;Carmen Guerra-Garcia","doi":"10.1016/j.combustflame.2024.113793","DOIUrl":"10.1016/j.combustflame.2024.113793","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Nanosecond pulsed plasmas have been demonstrated, both experimentally and numerically, to be beneficial for ignition, mainly through gas heating (at different timescales) and radical seeding. However, most studies focus on specific gas conditions, and little work has been done to understand how plasma performance is affected by fuel and oxygen content, at different gas temperatures and deposited energies. This is relevant to map the performance envelope of plasma-assisted combustion across different regimes, spanning from fuel-lean to fuel-rich operation, as well as oxygen-rich to oxygen-vitiated conditions, of interest to different industries. This work presents a computational effort to address a large parametric exploration of combustion environments and map out the actuation authority of plasmas under different conditions. The work uses a zero-dimensional plasma-combustion kinetics solver developed in-house to study the ignition of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;CH&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; mixtures with plasma assistance. A main contribution of the study is the detailed tracking of the energy, from the electrical input all the way to the thermal and kinetic effects that result in combustion enhancement. This extends prior works that focus on the first step of the energy transfer: from the electrical input to the electron-impact processes. Independent of the composition, four pathways stand out: (i) vibrational-translational relaxation, (ii) fast gas heating, (iii) &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; dissociation, and (iv) &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;CH&lt;/mi&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; dissociation. Results show that the activated energy pathways are highly dependent on gas state, composition, and pulse shape, and can explain the observed range in performance regarding ignition enhancement. The approach can be used to calculate the fractional energy deposition into the main pathways for any mixture or composition, including new fuels, and can be a valuable tool to construct phenomenological models of the plasma across combustion environments.&lt;/div&gt;&lt;div&gt;&lt;strong&gt;Novelty and significance statement&lt;/strong&gt;&lt;/div&gt;&lt;div&gt;This work maps the performance of plasma-assisted ignition over a broader range of combustion environments than prior works. Whereas most works focus on fuel/air mixtures, this work quantifies the impact of fuel content and oxygen dilution on plasma actuation. This is relevant to determine the possibilities of using plasma ignition across industries. The novelty of the model presented is the accurate tracking of the energy deposited by the plasma and the identification of the chemical pathways activated by the plasma. Although it is recognized as critical in the description of ","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"271 ","pages":"Article 113793"},"PeriodicalIF":5.8,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560744","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}