Pub Date : 2025-04-23DOI: 10.1016/j.combustflame.2025.114163
Hugo Keck , Christian Chauveau , Guillaume Legros , Stany Gallier , Fabien Halter
In a diffusive combustion regime, an aluminum droplet undergoing combustion forms an oxide cloud that surrounds the burning droplet. Thorough characterization of this cloud is crucial to the validation of the subsequent modeling. This paper makes a significant contribution to the field by providing an experimental procedure to resolve the spatial temperature profile within the oxide cloud. An electrodynamic levitator is used to observe the self-sustained combustion of aluminum particles with a radius of in atmospheric air, with negligible convective effects. The levitating device is coupled to an optical apparatus that allows for a light extinction method, thereby enabling the determination of size and concentration profiles of the nanometric alumina droplets, as introduced in previous works. The data from the previous study are employed in conjunction with a modulated absorption–emission (MAE) technique to ascertain a temperature profile that does not rely on the grey-body assumption. This technique is further enhanced by an optimization method to account for gaseous phase emissions, which typically hinder conventional temperature evaluation. Consequently, a spatially resolved temperature profile of the oxide cloud surrounding the burning droplet is obtained. Close to the surface of the droplet, a temperature of 2580 K is assessed. Then, a maximum temperature of about 3615 K is measured. As an additional outcome, gaseous emission profiles are obtained for three wavelengths and exhibit a notable correlation with a simulated gaseous suboxide concentration profile. The results presented in this work demonstrate a relatively high degree of consistency with expected temperatures.
Novelty and Significance Statement
This work presents a novel experimental method to obtain an unique temperature profile surrounding an isolated aluminum droplet in combustion. In conjunction with previous work, a non-intrusive, complete, and instantaneous characterization of the oxide smoke is now made possible, with the addition of the temperature profile to the known alumina particle size and concentration profiles. This comprehensive data set is presented for a fundamental case of a single levitating particle. The incorporation of the temperature profile provides an incomparable insight into alumina condensation processes and a detailed reference case for simulation purposes. The results presented in this work document the intricate condensation process of nanoparticles and highlight the limitations of current simulation methods.
{"title":"Temperature field measurement of a burning aluminum droplet","authors":"Hugo Keck , Christian Chauveau , Guillaume Legros , Stany Gallier , Fabien Halter","doi":"10.1016/j.combustflame.2025.114163","DOIUrl":"10.1016/j.combustflame.2025.114163","url":null,"abstract":"<div><div>In a diffusive combustion regime, an aluminum droplet undergoing combustion forms an oxide cloud that surrounds the burning droplet. Thorough characterization of this cloud is crucial to the validation of the subsequent modeling. This paper makes a significant contribution to the field by providing an experimental procedure to resolve the spatial temperature profile within the oxide cloud. An electrodynamic levitator is used to observe the self-sustained combustion of aluminum particles with a radius of <span><math><mrow><mn>35</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> in atmospheric air, with negligible convective effects. The levitating device is coupled to an optical apparatus that allows for a light extinction method, thereby enabling the determination of size and concentration profiles of the nanometric alumina droplets, as introduced in previous works. The data from the previous study are employed in conjunction with a modulated absorption–emission (MAE) technique to ascertain a temperature profile that does not rely on the grey-body assumption. This technique is further enhanced by an optimization method to account for gaseous phase emissions, which typically hinder conventional temperature evaluation. Consequently, a spatially resolved temperature profile of the oxide cloud surrounding the burning droplet is obtained. Close to the surface of the droplet, a temperature of 2580 K is assessed. Then, a maximum temperature of about 3615 K is measured. As an additional outcome, gaseous emission profiles are obtained for three wavelengths and exhibit a notable correlation with a simulated gaseous suboxide concentration profile. The results presented in this work demonstrate a relatively high degree of consistency with expected temperatures.</div><div><strong>Novelty and Significance Statement</strong></div><div>This work presents a novel experimental method to obtain an unique temperature profile surrounding an isolated aluminum droplet in combustion. In conjunction with previous work, a non-intrusive, complete, and instantaneous characterization of the oxide smoke is now made possible, with the addition of the temperature profile to the known alumina particle size and concentration profiles. This comprehensive data set is presented for a fundamental case of a single levitating particle. The incorporation of the temperature profile provides an incomparable insight into alumina condensation processes and a detailed reference case for simulation purposes. The results presented in this work document the intricate condensation process of nanoparticles and highlight the limitations of current simulation methods.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114163"},"PeriodicalIF":5.8,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143860000","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}
In a reflective shuttling detonation combustor (RSDC), detonation waves propagate between the two reflection walls of a thin combustion chamber. As the chamber is two-dimensional and does not have any curvature, optical and pressure measurements can be conducted simultaneously. In this study, pressure measurements as well as self-luminous and schlieren visualizations were performed using a chamber with a reflection wall distance of 90 mm with ethylene and oxygen. Consequently, the detonation wave number increased from 2 to 5 following the total mass flux, indicating that the wave number depended on the reflection wall distance because the maximum wave number increased with increasing distance. In addition, although the reflection wall distance was varied, the mode transition, in which the wave number increased from 1 to 2, 2 to 3, and 3 to 4, occurred at similar values to the critical value at which the maximum mixture fill height was non-dimensionalized by the cell size. The dimensionless detonation wave propagation distance, that is, the reflection wall distance divided by the wave number and maximum mixture fill height, was 3.0 ± 0.3, which is almost the same as that of the previous 45 mm combustor. Additionally, when the ratio of the reflective wall distance to the wave number is the same, the dimensionless quantities match, except in a few cases. Comparing the model results with the schlieren results, different trends were caused by non-ideal phenomena arising from the supply conditions, such as the equivalence ratio and the relationship between the plenum pressure and combustion pressure.
{"title":"Effect of reflection wall distance and supply conditions on reflective shuttling detonation combustor","authors":"Tasuku Nagaoka , Ken Matsuoka , Yusuke Takahashi , Hiroaki Watanabe , Noboru Itouyama , Akira Kawasaki , Jiro Kasahara , Akiko Matsuo","doi":"10.1016/j.combustflame.2025.114151","DOIUrl":"10.1016/j.combustflame.2025.114151","url":null,"abstract":"<div><div>In a reflective shuttling detonation combustor (RSDC), detonation waves propagate between the two reflection walls of a thin combustion chamber. As the chamber is two-dimensional and does not have any curvature, optical and pressure measurements can be conducted simultaneously. In this study, pressure measurements as well as self-luminous and schlieren visualizations were performed using a chamber with a reflection wall distance of 90 mm with ethylene and oxygen. Consequently, the detonation wave number increased from 2 to 5 following the total mass flux, indicating that the wave number depended on the reflection wall distance because the maximum wave number increased with increasing distance. In addition, although the reflection wall distance was varied, the mode transition, in which the wave number increased from 1 to 2, 2 to 3, and 3 to 4, occurred at similar values to the critical value at which the maximum mixture fill height was non-dimensionalized by the cell size. The dimensionless detonation wave propagation distance, that is, the reflection wall distance divided by the wave number and maximum mixture fill height, was 3.0 ± 0.3, which is almost the same as that of the previous 45 mm combustor. Additionally, when the ratio of the reflective wall distance to the wave number is the same, the dimensionless quantities match, except in a few cases. Comparing the model results with the schlieren results, different trends were caused by non-ideal phenomena arising from the supply conditions, such as the equivalence ratio and the relationship between the plenum pressure and combustion pressure.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"276 ","pages":"Article 114151"},"PeriodicalIF":5.8,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143854907","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}
Pub Date : 2025-04-21DOI: 10.1016/j.combustflame.2025.114185
Zhaohan Chu , Wanxiong Liao , Zhongkai Liu , Yiru Wang , Qifeng Hou , Feng Zhang , Chung K. Law , Bin Yang
In response to the interest in nitrogen-containing compounds as energetic materials, an experimental and kinetic study on the low-temperature oxidation of three butyl nitrites isomers, namely n‑butyl (NBN), isobutyl (IBN), and tert‑butyl (TBN) was performed. By measuring their ignition delays in a rapid compression machine (RCM) under 5–15 bar at temperatures from 550 to 630 K, a two-stage ignition behavior was observed for all the three nitrites, with the first-stage delays of TBN being shorter than those of NBN and IBN. A detailed kinetic mechanism was constructed and validated against the experimental data, and the production rate was analyzed to explain the first-stage ignition behavior. Specifically, the N−O bond dissociation reaction initiated the consumption of butyl nitrites isomers in all cases studied, which produced NO and different butoxy radicals (C4H9O). In the case of TBN, the decomposition of TC4H9O produces CH3 in the first-stage ignition. The abundant CH3 radical reacts with NO2 to produce CH3O, which further yields HO2 and CH2O through the reaction with O2. The inert HO2 radical is converted to OH through the reaction HO2 + NO = OH + NO2, resulting in the first-stage ignition. Meanwhile, the decomposition of PC4H9O and IC4H9O produces n-propyl and i-propyl radicals, respectively, in the cases of NBN and IBN. The reaction sequences of n-propyl and i-propyl radicals produce less HO2 radicals compared with that in TBN, leading to longer first-stage ignition time.
{"title":"On the two-stage auto-ignition of butyl nitrite isomers","authors":"Zhaohan Chu , Wanxiong Liao , Zhongkai Liu , Yiru Wang , Qifeng Hou , Feng Zhang , Chung K. Law , Bin Yang","doi":"10.1016/j.combustflame.2025.114185","DOIUrl":"10.1016/j.combustflame.2025.114185","url":null,"abstract":"<div><div>In response to the interest in nitrogen-containing compounds as energetic materials, an experimental and kinetic study on the low-temperature oxidation of three butyl nitrites isomers, namely n‑butyl (NBN), isobutyl (IBN), and tert‑butyl (TBN) was performed. By measuring their ignition delays in a rapid compression machine (RCM) under 5–15 bar at temperatures from 550 to 630 K, a two-stage ignition behavior was observed for all the three nitrites, with the first-stage delays of TBN being shorter than those of NBN and IBN. A detailed kinetic mechanism was constructed and validated against the experimental data, and the production rate was analyzed to explain the first-stage ignition behavior. Specifically, the N−O bond dissociation reaction initiated the consumption of butyl nitrites isomers in all cases studied, which produced NO and different butoxy radicals (C<sub>4</sub>H<sub>9</sub>O). In the case of TBN, the decomposition of TC<sub>4</sub>H<sub>9</sub>O produces CH<sub>3</sub> in the first-stage ignition. The abundant CH<sub>3</sub> radical reacts with NO<sub>2</sub> to produce CH<sub>3</sub>O, which further yields HO<sub>2</sub> and CH<sub>2</sub>O through the reaction with O<sub>2</sub>. The inert HO<sub>2</sub> radical is converted to OH through the reaction HO<sub>2</sub> + NO = OH + NO<sub>2</sub>, resulting in the first-stage ignition. Meanwhile, the decomposition of PC<sub>4</sub>H<sub>9</sub>O and IC<sub>4</sub>H<sub>9</sub>O produces n-propyl and i-propyl radicals, respectively, in the cases of NBN and IBN. The reaction sequences of n-propyl and i-propyl radicals produce less HO<sub>2</sub> radicals compared with that in TBN, leading to longer first-stage ignition time.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114185"},"PeriodicalIF":5.8,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851750","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}
Pub Date : 2025-04-19DOI: 10.1016/j.combustflame.2025.114180
Teng Zhang , Lang Chen , Yao Long , Bin Zhang , Tuo Yang , Kun Yang , Jianying Lu , Danyang Liu , Jun Chen
The instantaneous high-energy release characteristic of high-energy-density materials (HEDMs) renders them an essential component of high-energy propellants or explosives. Hence, the prediction of performance of HEDMs is of paramount significance for its engineering application. In this paper, using first-principle molecular dynamics approach with multi-scale shock technique, the detonation reaction process of CL-20 is studied, and the detailed chemical reaction kinetics are analyzed. Combining quantum chemical calculation, the first chemical kinetics model (FP-CL20 model) which contains 153 species and 412 elementary reactions is constructed. The pyrolysis and detonation performance of the CL-20 explosive under experimental conditions are predicted by using the FP-CL20 model. Within the framework of the approximation, the agreement of predicted key physical quantities of pyrolysis and detonation for CL-20 with the experimental results is satisfactory. FP-CL20 model also reveals that reaction N2O+NONO2+N2 and CO+NO2NO+CO2 play key roles in the formation of N2 and CO2 under detonation. While different from detonation, NCO+NON2+CO2 and NCO+NO2CO2+N2O are the main reactions for the formation of N2 and CO2 under pyrolysis. Within the detonation reaction zone, the oxidation of small molecular N-heterochains (L-NCNCO+OHNCN+HOCO) and small molecular carbon oxides (HOCO+OHCO2+H2O) are key reactions that affect the detonation reaction zone time. Our studies offer a novel insight into understanding the pyrolysis and detonation reaction mechanism of CL-20, also paving the way for the construction of chemical kinetics model and the performance prediction of HEDMs.
{"title":"Performance prediction of high-energy-density material CL-20 based on FP-CL20 chemical kinetics model","authors":"Teng Zhang , Lang Chen , Yao Long , Bin Zhang , Tuo Yang , Kun Yang , Jianying Lu , Danyang Liu , Jun Chen","doi":"10.1016/j.combustflame.2025.114180","DOIUrl":"10.1016/j.combustflame.2025.114180","url":null,"abstract":"<div><div>The instantaneous high-energy release characteristic of high-energy-density materials (HEDMs) renders them an essential component of high-energy propellants or explosives. Hence, the prediction of performance of HEDMs is of paramount significance for its engineering application. In this paper, using first-principle molecular dynamics approach with multi-scale shock technique, the detonation reaction process of CL-20 is studied, and the detailed chemical reaction kinetics are analyzed. Combining quantum chemical calculation, the first chemical kinetics model (FP-CL20 model) which contains 153 species and 412 elementary reactions is constructed. The pyrolysis and detonation performance of the CL-20 explosive under experimental conditions are predicted by using the FP-CL20 model. Within the framework of the approximation, the agreement of predicted key physical quantities of pyrolysis and detonation for CL-20 with the experimental results is satisfactory. FP-CL20 model also reveals that reaction N<sub>2</sub>O+NO<img>NO<sub>2</sub>+N<sub>2</sub> and CO+NO<sub>2</sub><img>NO+CO<sub>2</sub> play key roles in the formation of N<sub>2</sub> and CO<sub>2</sub> under detonation. While different from detonation, NCO+NO<img>N<sub>2</sub>+CO<sub>2</sub> and NCO+NO<sub>2</sub><img>CO<sub>2</sub>+N<sub>2</sub>O are the main reactions for the formation of N<sub>2</sub> and CO<sub>2</sub> under pyrolysis. Within the detonation reaction zone, the oxidation of small molecular N-heterochains (L-NCNCO+OH<img>NCN+HOCO) and small molecular carbon oxides (HOCO+OH<img>CO<sub>2</sub>+H<sub>2</sub>O) are key reactions that affect the detonation reaction zone time. Our studies offer a novel insight into understanding the pyrolysis and detonation reaction mechanism of CL-20, also paving the way for the construction of chemical kinetics model and the performance prediction of HEDMs.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114180"},"PeriodicalIF":5.8,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848624","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}
Pub Date : 2025-04-19DOI: 10.1016/j.combustflame.2025.114189
Jinghui Wang , Junwei Li , Ye He , Bingyin Wang , Xiaodong Wang , Qiang Li , Shidi Ai , Ningfei Wang
Acceleration can cause adverse effects such as abnormal propellant burning rates and irregular interior ballistics in the combustion chamber. To address the issue of solid rocket motors experiencing high accelerations during highly maneuverable flight, this study conducted firing tests on typical solid propellants under acceleration conditions ranging from 0 g to 150 g. A new burning rate model for aluminized propellants in acceleration fields was developed, and the microscopic combustion mechanism of aluminized propellants under these conditions was elucidated. The results indicate that as acceleration increases, the burning rate gain initially increases and then plateaus. The amplitude of burning rate fluctuations significantly exceeds that of pressure fluctuations. Under acceleration conditions of 30 g to 70 g, the interior ballistic curve during the motor's operation phase shows a non-plateau behavior, characterized by an initial pressure increase and subsequent decrease. The retention and agglomeration of aluminum particles on the propellant burning surface were identified as the primary causes of abnormal changes in propellant burning rate and combustion chamber pressure. Simultaneously, the new burning rate model was employed to calculate the burning rate gain ratios under various acceleration conditions, with a maximum value reaching 1.54. The theoretical calculation of the maximum burning rate gain exhibited an error of 4 % compared to the experimental actual values. Additionally, the inner ballistic variation process under different acceleration conditions was predicted, revealing that the theoretically calculated pressure curves were in close agreement with the measured pressure curve trends.
{"title":"The study on the influence of acceleration on the combustion performance of solid rocket motor","authors":"Jinghui Wang , Junwei Li , Ye He , Bingyin Wang , Xiaodong Wang , Qiang Li , Shidi Ai , Ningfei Wang","doi":"10.1016/j.combustflame.2025.114189","DOIUrl":"10.1016/j.combustflame.2025.114189","url":null,"abstract":"<div><div>Acceleration can cause adverse effects such as abnormal propellant burning rates and irregular interior ballistics in the combustion chamber. To address the issue of solid rocket motors experiencing high accelerations during highly maneuverable flight, this study conducted firing tests on typical solid propellants under acceleration conditions ranging from 0 g to 150 g. A new burning rate model for aluminized propellants in acceleration fields was developed, and the microscopic combustion mechanism of aluminized propellants under these conditions was elucidated. The results indicate that as acceleration increases, the burning rate gain initially increases and then plateaus. The amplitude of burning rate fluctuations significantly exceeds that of pressure fluctuations. Under acceleration conditions of 30 g to 70 g, the interior ballistic curve during the motor's operation phase shows a non-plateau behavior, characterized by an initial pressure increase and subsequent decrease. The retention and agglomeration of aluminum particles on the propellant burning surface were identified as the primary causes of abnormal changes in propellant burning rate and combustion chamber pressure. Simultaneously, the new burning rate model was employed to calculate the burning rate gain ratios under various acceleration conditions, with a maximum value reaching 1.54. The theoretical calculation of the maximum burning rate gain exhibited an error of 4 % compared to the experimental actual values. Additionally, the inner ballistic variation process under different acceleration conditions was predicted, revealing that the theoretically calculated pressure curves were in close agreement with the measured pressure curve trends.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114189"},"PeriodicalIF":5.8,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848069","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}
Pub Date : 2025-04-19DOI: 10.1016/j.combustflame.2025.114176
Shuyao Chen , Bingzhi Liu , Qiang Xu , Qingbo Zhu , Long Zhu , Zhandong Wang
Toluene is the simplest alkylated aromatic and an important component of transportation fuel. The low-temperature oxidation kinetics of toluene is crucial for the development of advanced combustion engines. In this work, we studied the low-temperature oxidation of toluene in a jet-stirred reactor (JSR) with ozone addition, from the temperature range of 350 K to 785 K. Key intermediates such as formaldehyde, benzaldehyde, benzene, phenol, furfural, benzyl alcohol and cresols were measured and quantified using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The hydroperoxides were also detected, such as hydrogen peroxide, methyl hydroperoxide, and benzyl hydroperoxide. The detailed data were used to evaluate the low-temperature oxidation chemistry of toluene by four models, which were developed by Nancy University, Lawrence Livermore National Laboratory, Politecnico di Milano and RWTH Aachen University. Large deviation between experimental measurement and model prediction was observed, especially for the reaction intermediates. We discussed the differences in predictions by these models, and we tentatively improved the low-temperature combustion kinetics of toluene based on the model from Nancy University, with a particular focus on the reaction network of benzyl and phenyl radical. The reaction of benzyl with ozone was considered in this work, and it is important for benzoxyl radical formation. Additionally, two pathways for the formation of benzyl hydroperoxide were considered, which contributes to a better prediction of benzyl hydroperoxide. This work also focuses on discussing the reaction network of the phenoxy radical with O atom, suggesting that the pathway leading to the C4H5 radical and CO is the main reaction channel under our experimental conditions. The improved Nancy model yielded a better prediction for the intermediates and products in the low-temperature oxidation of toluene. This work provides a deeper understanding of the low-temperature oxidation chemistry of alkylated aromatics, which are valuable to improve the reaction network and to develop the low-temperature combustion models of alkylated aromatics.
甲苯是最简单的烷基芳烃，也是运输燃料的重要成分。甲苯的低温氧化动力学对先进内燃机的开发至关重要。本研究采用同步辐射真空紫外光离子化质谱法（SVUV-PIMS）对甲苯在 350 K 至 785 K 温度范围内的低温氧化过程进行了研究，并对甲醛、苯甲醛、苯、苯酚、糠醛、苯甲醇和甲酚等关键中间产物进行了测量和定量。还检测了氢过氧化物，如过氧化氢、氢过氧化甲酯和氢过氧化苄酯。南希大学、劳伦斯-利弗莫尔国家实验室、米兰理工大学和亚琛工业大学开发了四种模型，利用这些详细数据对甲苯的低温氧化化学反应进行评估。实验测量与模型预测之间存在很大偏差，尤其是在反应中间产物方面。我们讨论了这些模型预测的差异，并在南希大学模型的基础上初步改进了甲苯的低温燃烧动力学，特别关注了苄基和苯基自由基的反应网络。这项工作考虑了苄基与臭氧的反应，这对苯并氧自由基的形成非常重要。此外，还考虑了形成过氧化氢苄基的两种途径，这有助于更好地预测过氧化氢苄基。这项工作还重点讨论了苯氧自由基与 O 原子的反应网络，表明在我们的实验条件下，通向 C4H5 自由基和 CO 的途径是主要的反应通道。改进后的 Nancy 模型能更好地预测甲苯低温氧化过程中的中间产物和生成物。这项工作加深了对烷基芳烃低温氧化化学反应的理解，对完善反应网络和开发烷基芳烃低温燃烧模型具有重要价值。
{"title":"Probing the ozone-assisted low-temperature oxidation chemistry of toluene","authors":"Shuyao Chen , Bingzhi Liu , Qiang Xu , Qingbo Zhu , Long Zhu , Zhandong Wang","doi":"10.1016/j.combustflame.2025.114176","DOIUrl":"10.1016/j.combustflame.2025.114176","url":null,"abstract":"<div><div>Toluene is the simplest alkylated aromatic and an important component of transportation fuel. The low-temperature oxidation kinetics of toluene is crucial for the development of advanced combustion engines. In this work, we studied the low-temperature oxidation of toluene in a jet-stirred reactor (JSR) with ozone addition, from the temperature range of 350 K to 785 K. Key intermediates such as formaldehyde, benzaldehyde, benzene, phenol, furfural, benzyl alcohol and cresols were measured and quantified using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). The hydroperoxides were also detected, such as hydrogen peroxide, methyl hydroperoxide, and benzyl hydroperoxide. The detailed data were used to evaluate the low-temperature oxidation chemistry of toluene by four models, which were developed by Nancy University, Lawrence Livermore National Laboratory, Politecnico di Milano and RWTH Aachen University. Large deviation between experimental measurement and model prediction was observed, especially for the reaction intermediates. We discussed the differences in predictions by these models, and we tentatively improved the low-temperature combustion kinetics of toluene based on the model from Nancy University, with a particular focus on the reaction network of benzyl and phenyl radical. The reaction of benzyl with ozone was considered in this work, and it is important for benzoxyl radical formation. Additionally, two pathways for the formation of benzyl hydroperoxide were considered, which contributes to a better prediction of benzyl hydroperoxide. This work also focuses on discussing the reaction network of the phenoxy radical with O atom, suggesting that the pathway leading to the C<sub>4</sub>H<sub>5</sub> radical and CO is the main reaction channel under our experimental conditions. The improved Nancy model yielded a better prediction for the intermediates and products in the low-temperature oxidation of toluene. This work provides a deeper understanding of the low-temperature oxidation chemistry of alkylated aromatics, which are valuable to improve the reaction network and to develop the low-temperature combustion models of alkylated aromatics.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114176"},"PeriodicalIF":5.8,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850335","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}
Pub Date : 2025-04-18DOI: 10.1016/j.combustflame.2025.114187
Shixing Wang , Ayman M. Elbaz , Zhihua Wang , William L. Roberts
Experiments of the laminar and turbulent flame speed of typical E-fuels blended with ammonia: methanol/ammonia/(CH3OH/NH3)/air, ethyl-acetate/ammonia/(EA/NH3)/air, and dimethoxymethane/ammonia/(DMM/NH3)/air under atmospheric and elevated pressures (1 and 3 atm) are conducted in a fan-stirred constant volume combustion chamber, with initial temperature of 373 K. The results show that turbulent flame speed (ST) follow the same ranking order as laminar flame speed (SL) at fuel-lean side from high to low as: DMM, CH3OH, and EA; while with ammonia addition, CH3OH/NH3 and EA/NH3 have similar SL and ST values; and at fuel-rich side, DMM and EA show increasing ST and ST/SL values than at fuel-lean side Meanwhile, the measured Markstein length (Lb) is decreasing towards the fuel-rich side and even becomes negative for EA. Ammonia addition enhances the turbulent flame wrinkling and deformation from the morphology analyses, and this leads to E-fuel/NH3 blends always having higher normalized turbulent flame speed (ST/SL) than pure E-fuel. Next, we test several different turbulent flame speed correlations composed of (u'/SL) and (lT/lF), it is found that the power exponents of (u'/SL) and (lT/lF) do not necessarily have to be equal; they change as the turbulent regime varies in different zones. ST/SL/Ka = a(Da/Le)b performs best among all correlation types with 0.5 ≤ b ≤ 1 corresponding to the Damköhler's two limits. Comparing three types of Lewis number, it is found that volume based LeV has the best fitting goodness in the correlation of ST/SL/Ka = a(Da/Le)b. Taking into account the developing flame brush thickness, wrinkling ratio and integral length scale as a function of radius, the flame radius based DaR correlations are proposed: ST/SL/γ = a(DaR/Le)b where 0.5 ≤ b ≤ 1 which can unify present experimental data with Lewis number larger than unity and previous data with Lewis number less than unity.
在初始温度为 373 K 的风扇搅拌式恒容燃烧室中，对甲醇/氨/(CH3OH/NH3)/空气、乙酸乙酯/氨/(EA/NH3)/空气和二甲氧基甲烷/氨/(DMM/NH3)/空气等典型掺氨电子燃料在大气压和高压（1 atm 和 3 atm）下的层流和湍流火焰速度进行了实验。结果表明，在燃料贫乏侧，湍流火焰速度（ST）与层流火焰速度（SL）从高到低的顺序相同：同时，测得的马克斯坦长度（Lb）在燃料富裕侧逐渐减小，EA 甚至变为负值。从形态分析来看，氨的加入增强了湍流火焰的起皱和变形，这导致 E-燃料/NH3 混合物的归一化湍流火焰速度（ST/SL）始终高于纯 E-燃料。接下来，我们测试了由（u'/SL）和（lT/lF）组成的几种不同的湍流火焰速度相关性，发现（u'/SL）和（lT/lF）的功率指数并不一定相等；它们会随着不同区域湍流机制的变化而变化。ST/SL/Ka = a(Da/Le)b 在所有相关类型中表现最佳，0.5 ≤ b ≤ 1 对应于达姆克勒的两个极限。比较三种路易斯数发现，基于体积的 LeV 在 ST/SL/Ka = a(Da/Le)b 的相关性中拟合效果最好。考虑到发展中火焰刷厚度、皱褶率和整体长度尺度与半径的函数关系，提出了基于火焰半径的 DaR 相关性：ST/SL/γ = a(DaR/Le)b 其中 0.5 ≤ b ≤ 1 可以统一目前路易斯数大于一的实验数据和以前路易斯数小于一的数据。
{"title":"The laminar and turbulent flame speed of methanol/ammonia/air, ethyl-acetate/ammonia/air, and dimethoxymethane/ammonia/air under atmospheric and elevated pressures","authors":"Shixing Wang , Ayman M. Elbaz , Zhihua Wang , William L. Roberts","doi":"10.1016/j.combustflame.2025.114187","DOIUrl":"10.1016/j.combustflame.2025.114187","url":null,"abstract":"<div><div>Experiments of the laminar and turbulent flame speed of typical E-fuels blended with ammonia: methanol/ammonia/(CH<sub>3</sub>OH/NH<sub>3</sub>)/air, ethyl-acetate/ammonia/(EA/NH<sub>3</sub>)/air, and dimethoxymethane/ammonia/(DMM/NH<sub>3</sub>)/air under atmospheric and elevated pressures (1 and 3 atm) are conducted in a fan-stirred constant volume combustion chamber, with initial temperature of 373 K. The results show that turbulent flame speed (<em>S</em><sub>T</sub>) follow the same ranking order as laminar flame speed (<em>S</em><sub>L</sub>) at fuel-lean side from high to low as: DMM, CH<sub>3</sub>OH, and EA; while with ammonia addition, CH<sub>3</sub>OH/NH<sub>3</sub> and EA/NH<sub>3</sub> have similar <em>S</em><sub>L</sub> and <em>S</em><sub>T</sub> values; and at fuel-rich side, DMM and EA show increasing <em>S</em><sub>T</sub> and <em>S</em><sub>T</sub>/<em>S</em><sub>L</sub> values than at fuel-lean side Meanwhile, the measured Markstein length (<em>L</em><sub>b</sub>) is decreasing towards the fuel-rich side and even becomes negative for EA. Ammonia addition enhances the turbulent flame wrinkling and deformation from the morphology analyses, and this leads to E-fuel/NH<sub>3</sub> blends always having higher normalized turbulent flame speed (<em>S</em><sub>T</sub>/<em>S</em><sub>L</sub>) than pure E-fuel. Next, we test several different turbulent flame speed correlations composed of (<em>u'</em>/<em>S</em><sub>L</sub>) and (<em>l</em><sub>T</sub>/<em>l</em><sub>F</sub>), it is found that the power exponents of (<em>u'</em>/<em>S</em><sub>L</sub>) and (<em>l</em><sub>T</sub>/<em>l</em><sub>F</sub>) do not necessarily have to be equal; they change as the turbulent regime varies in different zones. <em>S</em><sub>T</sub>/<em>S</em><sub>L</sub>/<em>Ka</em> = <em>a</em>(<em>Da</em>/<em>Le</em>)<em><sup>b</sup></em> performs best among all correlation types with 0.5 ≤ <em>b</em> ≤ 1 corresponding to the Damköhler's two limits. Comparing three types of Lewis number, it is found that volume based <em>Le</em><sub>V</sub> has the best fitting goodness in the correlation of <em>S</em><sub>T</sub>/<em>S</em><sub>L</sub>/<em>Ka</em> = <em>a</em>(<em>Da</em>/<em>Le</em>)<em><sup>b</sup></em>. Taking into account the developing flame brush thickness, wrinkling ratio and integral length scale as a function of radius, the flame radius based <em>Da</em><sub>R</sub> correlations are proposed: <em>S</em><sub>T</sub>/<em>S</em><sub>L</sub>/<em>γ</em> = <em>a</em>(<em>Da<sub>R</sub></em>/<em>Le</em>)<em><sup>b</sup></em> where 0.5 ≤ <em>b</em> ≤ 1 which can unify present experimental data with Lewis number larger than unity and previous data with Lewis number less than unity.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114187"},"PeriodicalIF":5.8,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848625","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}
Pub Date : 2025-04-18DOI: 10.1016/j.combustflame.2025.114186
Jie Liu , Wenkai Liang , Chung K. Law
Analytical expressions for the classical Z-shaped pressure-vs-temperature explosion limit curve of hydrogen/oxygen mixtures are expeditiously derived based on the leading-order, algebraically linear reactions between the (H, HO2, H2O2) radicals and the (H2, O2) background reactants. The analysis yields a detailed ignition mechanism (DIM) and then a skeletal ignition mechanism (SIM) describing the Z-curve, both of which result in close agreement with those computationally obtained with the original reaction mechanism. The solution leads to the ready identification of the first-second and second-third quadratic limits, the associated lower and upper turning points, and the single first, second, and third limits, with the concomitant demonstration that the conventional second limit, , represented by the classical crossover-temperature, is inadequate to describe the transition between the first and third limits. A curvature-reversal, inflection point embedded within the second limit is identified, leading to the precise indication of the controlling transition chemistry between the low- and high-pressure regimes.
{"title":"Theory of explosion limits of hydrogen/oxygen mixtures","authors":"Jie Liu , Wenkai Liang , Chung K. Law","doi":"10.1016/j.combustflame.2025.114186","DOIUrl":"10.1016/j.combustflame.2025.114186","url":null,"abstract":"<div><div>Analytical expressions for the classical Z-shaped pressure-vs-temperature explosion limit curve of hydrogen/oxygen mixtures are expeditiously derived based on the leading-order, algebraically linear reactions between the (H, HO<sub>2</sub>, H<sub>2</sub>O<sub>2</sub>) radicals and the (H<sub>2</sub>, O<sub>2</sub>) background reactants. The analysis yields a detailed ignition mechanism (DIM) and then a skeletal ignition mechanism (SIM) describing the Z-curve, both of which result in close agreement with those computationally obtained with the original reaction mechanism. The solution leads to the ready identification of the first-second and second-third quadratic limits, the associated lower and upper turning points, and the single first, second, and third limits, with the concomitant demonstration that the conventional second limit, <span><math><mrow><mrow><mo>[</mo><mrow><mi>M</mi></mrow><mo>]</mo></mrow><mo>=</mo><mn>2</mn><msub><mi>k</mi><mn>1</mn></msub><mo>/</mo><msub><mi>k</mi><mn>9</mn></msub></mrow></math></span>, represented by the classical crossover-temperature, is inadequate to describe the transition between the first and third limits. A curvature-reversal, inflection point embedded within the second limit is identified, leading to the precise indication of the controlling transition chemistry between the low- and high-pressure regimes.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114186"},"PeriodicalIF":5.8,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843760","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}
Pub Date : 2025-04-17DOI: 10.1016/j.combustflame.2025.114149
Boris Kruljevic, Stéphane Q.E. Wang, Nicolas Vaysse, Jean-Baptiste Perrin-Terrin, Daniel Durox, Antoine Renaud, Christophe O. Laux, Benoît Fiorina
Plasma-assisted combustion (PAC) using Nanosecond Repetitively Pulsed (NRP) discharges is an efficient method to extend the lean blowout limit of flames, as shown in numerous experiments. In this study, the underlying mechanisms by which NRP discharges extend the lean blowout limit in hydrogen-air flames are analyzed numerically for the first time. The computations are performed using Large Eddy Simulations (LES) coupled with a semi-empirical model for the NRP discharges. The blowout is triggered at constant hydrogen mass flow rate (i.e., constant flame thermal power) through a very slow increase of the injected air mass flow rate, resulting in a decrease of the global equivalence ratio. A PAC configuration featuring NRP discharges at a frequency of 15 kHz and a 1.5 mJ deposited energy per pulse is computed, for which the experiments have shown a 20% reduction of the lean blowout equivalence ratio, by using NRP discharges. The case without plasma is also computed. These two configurations are first compared in terms of combustion efficiency. Next, results of blowout simulations are presented. The LES is able to predict the blowout equivalence ratios accurately for both the case without plasma (0.9% error) and with the NRP discharges (2.8% error). In the case without plasma, blowout is triggered through the dilution of burnt gases by fresh gases, which penetrated the inner recirculation zone at sufficiently low global equivalence ratios. Plasma triggers the oxidation of these pockets of fresh gases, resulting in the production of radicals and heat, which stabilizes the flame.
Novelty and Significance Statement
This is the first time that simulations are performed of a plasma-assisted combustion (PAC) experiment in pure hydrogen flames. Also, for the first time, a PAC phenomenological model (Castela et al., 2016) is used to predict the lean blowout (LBO) limit of a flame assisted by plasma and the results are evaluated through comparisons with experimental data. The interactions between the flame and the Nanosecond Repetitively Pulsed (NRP) discharges at the LBO limit are studied numerically. The NRP discharges promote the oxidation of pockets of fresh gases, resulting in the production of radicals and heat, which stabilizes the flame and extends the LBO limit.
{"title":"Numerical study on the impact of Nanosecond Repetitively Pulsed discharges on the lean blowout limit for a hydrogen/air swirled flame","authors":"Boris Kruljevic, Stéphane Q.E. Wang, Nicolas Vaysse, Jean-Baptiste Perrin-Terrin, Daniel Durox, Antoine Renaud, Christophe O. Laux, Benoît Fiorina","doi":"10.1016/j.combustflame.2025.114149","DOIUrl":"10.1016/j.combustflame.2025.114149","url":null,"abstract":"<div><div>Plasma-assisted combustion (PAC) using Nanosecond Repetitively Pulsed (NRP) discharges is an efficient method to extend the lean blowout limit of flames, as shown in numerous experiments. In this study, the underlying mechanisms by which NRP discharges extend the lean blowout limit in hydrogen-air flames are analyzed numerically for the first time. The computations are performed using Large Eddy Simulations (LES) coupled with a semi-empirical model for the NRP discharges. The blowout is triggered at constant hydrogen mass flow rate (i.e., constant flame thermal power) through a very slow increase of the injected air mass flow rate, resulting in a decrease of the global equivalence ratio. A PAC configuration featuring NRP discharges at a frequency of 15 kHz and a 1.5 mJ deposited energy per pulse is computed, for which the experiments have shown a 20% reduction of the lean blowout equivalence ratio, by using NRP discharges. The case without plasma is also computed. These two configurations are first compared in terms of combustion efficiency. Next, results of blowout simulations are presented. The LES is able to predict the blowout equivalence ratios accurately for both the case without plasma (0.9% error) and with the NRP discharges (2.8% error). In the case without plasma, blowout is triggered through the dilution of burnt gases by fresh gases, which penetrated the inner recirculation zone at sufficiently low global equivalence ratios. Plasma triggers the oxidation of these pockets of fresh gases, resulting in the production of radicals and heat, which stabilizes the flame.</div><div><strong>Novelty and Significance Statement</strong></div><div>This is the first time that simulations are performed of a plasma-assisted combustion (PAC) experiment in pure hydrogen flames. Also, for the first time, a PAC phenomenological model (Castela et al., 2016) is used to predict the lean blowout (LBO) limit of a flame assisted by plasma and the results are evaluated through comparisons with experimental data. The interactions between the flame and the Nanosecond Repetitively Pulsed (NRP) discharges at the LBO limit are studied numerically. The NRP discharges promote the oxidation of pockets of fresh gases, resulting in the production of radicals and heat, which stabilizes the flame and extends the LBO limit.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114149"},"PeriodicalIF":5.8,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843761","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}
Pub Date : 2025-04-16DOI: 10.1016/j.combustflame.2025.114139
M. Richter , J. Lill , R.S. Barlow , A. Gruber , A. Dreizler , J.R. Dawson , D. Geyer
<div><div>Ammonia-based fuels have been identified as a promising alternative as zero-carbon energy carriers due to their high energy density and simpler logistics compared to hydrogen. As a disadvantage, the presence of fuel-bound nitrogen can lead to order of magnitude higher emissions of undesired nitric oxide (NO), nitrogen dioxide (NO<sub>2</sub>) and nitrous oxide (N<sub>2</sub>O) compared to more conventional fuels. Presently, chemical kinetics schemes for the combustion of ammonia and ammonia blends show large variations in the prediction of NO and there is a lack of quantitative experimental data to validate and optimize these reaction mechanisms. This paper presents measurements of NO in the product gases of laminar premixed NH<sub>3</sub>/H<sub>2</sub>/N<sub>2</sub> air flames on a flat-flame burner for 4 different ammonia decomposition ratios and over a range of equivalence ratios using laser-induced fluorescence in the NO A-X (0,1) system. A linear calibration approach based on the addition of NO to a lean premixed CH<sub>4</sub> flame is presented. Initial signal treatment includes the correction of laser absorption, fluorescence absorption (signal trapping) and fluctuations in laser energy. The LIF signals are corrected for changes in the Boltzmann fraction, line overlap, number density, and quenching between calibration and measurement, which requires knowledge of the local temperature and mole fractions of the main species. Temperature measurements using N<sub>2</sub> thermometry, where a theoretical N<sub>2</sub> Raman spectrum is fitted to an experimental N<sub>2</sub> Raman signal, excited by a 532 nm cw laser, allow characterization of the local near-adiabatic flame conditions as a function of operating conditions and adjustment of the signal corrections to the local temperature. Major species are extracted from 1-D simulations. The measured NO mole fractions are compared with five recent chemical kinetic schemes, which show good agreement for rich mixtures, however, a systematic underprediction of NO is found for stoichiometric and lean mixtures.</div><div><strong>Novelty and significance</strong></div><div>Emissions of NO are a major challenge for advancement of ammonia as a carbon-free fuel, yet very few measurements of NO levels in ammonia flames exist in the literature. In this paper, we present much needed quantitative experimental data on NO emissions from premixed NH<sub>3</sub>/H<sub>2</sub>/N<sub>2</sub>-air flames using laser-induced fluorescence (LIF). Our diagnostic approach employs a linear calibration method based on the addition of NO to a lean CH<sub>4</sub> flame. Post-flame temperatures are measured by Raman spectroscopy to ensure accuracy of the local thermochemical states used in converting LIF signals to quantitative NO concentrations, accounting for variations in number density, electronic quenching, Boltzmann fraction, and the line overlap integral. Additionally, laser absorption and signal trapping ar
{"title":"Quantification of NO in the post-flame region of laminar premixed ammonia/hydrogen/nitrogen-air flames using laser induced fluorescence","authors":"M. Richter , J. Lill , R.S. Barlow , A. Gruber , A. Dreizler , J.R. Dawson , D. Geyer","doi":"10.1016/j.combustflame.2025.114139","DOIUrl":"10.1016/j.combustflame.2025.114139","url":null,"abstract":"<div><div>Ammonia-based fuels have been identified as a promising alternative as zero-carbon energy carriers due to their high energy density and simpler logistics compared to hydrogen. As a disadvantage, the presence of fuel-bound nitrogen can lead to order of magnitude higher emissions of undesired nitric oxide (NO), nitrogen dioxide (NO<sub>2</sub>) and nitrous oxide (N<sub>2</sub>O) compared to more conventional fuels. Presently, chemical kinetics schemes for the combustion of ammonia and ammonia blends show large variations in the prediction of NO and there is a lack of quantitative experimental data to validate and optimize these reaction mechanisms. This paper presents measurements of NO in the product gases of laminar premixed NH<sub>3</sub>/H<sub>2</sub>/N<sub>2</sub> air flames on a flat-flame burner for 4 different ammonia decomposition ratios and over a range of equivalence ratios using laser-induced fluorescence in the NO A-X (0,1) system. A linear calibration approach based on the addition of NO to a lean premixed CH<sub>4</sub> flame is presented. Initial signal treatment includes the correction of laser absorption, fluorescence absorption (signal trapping) and fluctuations in laser energy. The LIF signals are corrected for changes in the Boltzmann fraction, line overlap, number density, and quenching between calibration and measurement, which requires knowledge of the local temperature and mole fractions of the main species. Temperature measurements using N<sub>2</sub> thermometry, where a theoretical N<sub>2</sub> Raman spectrum is fitted to an experimental N<sub>2</sub> Raman signal, excited by a 532 nm cw laser, allow characterization of the local near-adiabatic flame conditions as a function of operating conditions and adjustment of the signal corrections to the local temperature. Major species are extracted from 1-D simulations. The measured NO mole fractions are compared with five recent chemical kinetic schemes, which show good agreement for rich mixtures, however, a systematic underprediction of NO is found for stoichiometric and lean mixtures.</div><div><strong>Novelty and significance</strong></div><div>Emissions of NO are a major challenge for advancement of ammonia as a carbon-free fuel, yet very few measurements of NO levels in ammonia flames exist in the literature. In this paper, we present much needed quantitative experimental data on NO emissions from premixed NH<sub>3</sub>/H<sub>2</sub>/N<sub>2</sub>-air flames using laser-induced fluorescence (LIF). Our diagnostic approach employs a linear calibration method based on the addition of NO to a lean CH<sub>4</sub> flame. Post-flame temperatures are measured by Raman spectroscopy to ensure accuracy of the local thermochemical states used in converting LIF signals to quantitative NO concentrations, accounting for variations in number density, electronic quenching, Boltzmann fraction, and the line overlap integral. Additionally, laser absorption and signal trapping ar","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"277 ","pages":"Article 114139"},"PeriodicalIF":5.8,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834718","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}
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