Article
Thermodynamics
Berk Can Duva, Lauren Elizabeth Chance, Elisa Toulson
Summary: The study investigated the effect of lower radius limits on extrapolation results of stretch models for spherically expanding flames, identifying a critical lower radius limit (R-L,R-critical) that converges laminar flame speed and burned gas Markstein length values. The critical lower radius limit strongly depends on the burned gas Markstein number (Ma(b)), with a correlation shown as |Ma(b)| = 0.8424*R-L,R-critical. This approach was used to correct laminar flame speeds and burned gas Markstein lengths for methane, hydrogen, propane, and iso-octane flames, resulting in comparisons with previously published experimental data.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2021)
Article
Thermodynamics
Haoyang Li, Jinyuan Hao, Zhiming Du, Tianwei Zhang
Summary: This study investigates the effect and mechanism of fine water mist on suppressing the flame of red pine wood pyrolysis gas. The results show that the addition of fine water mist affects the speed and height of the flame, while the ratio of CO/H-2 in the pyrolysis gas composition of red pine wood determines the combustion promotion effect of the fine water mist.
CASE STUDIES IN THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Keisuke Nakahara, Akira Yoshida, Makihito Nishioka
Summary: Experiments and numerical simulations were conducted to investigate the impact of water mist on the minimum ignition energy and flammability limits of C3H8-air mixtures. Results showed that water mist can increase the minimum ignition energy density, but its suppression effectiveness depends on the equivalence ratio and mass fraction of water mist. The smaller the diameter of the water mist, the greater the suppression potential.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Luming Fan, Bo Tian, Cheng Tung Chong, Mohammad Nazri Mohd Jaafar, Kenji Tanno, Dante McGrath, Pedro M. de Oliveira, Bernd Rogg, Simone Hochgreb
Summary: In this study, the impact of fuel droplets on stretched laminar flame speeds was investigated by adding small acetone droplets to methane/air mixtures. It was found that the presence of droplets altered the relationship between flame speed and strain rate, especially under rich conditions. Unlike fully vaporized flames, a two-stage reaction flame structure was observed with droplets, indicating a change in flame behavior.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Yiqing Wang, Wang Han, Antonio Attili, Zheng Chen
Summary: This study investigates the impact of soot formation on flame speed measurements under fuel-rich conditions by simulating one-dimensional outwardly propagating spherical flames. The results show that soot dynamics and morphology are highly sensitive to changes in equivalence ratio and flame radius.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Michael J. Hegetschweiler, John L. Pagliaro, Lukas Berger, Raik Hesse, Joachim Beeckmann, Chaimae Bariki, Heinz Pitsch, Gregory T. Linteris
Summary: The study investigated the burning velocities of mixtures of R-32 with air at different equivalence ratios, finding that the effects of stretch and radiation occur simultaneously. Different data reduction approaches had significant effects on the burning velocities inferred from experiments and simulations, and a new flame radius tracking method provided improved agreement with predicted gas velocity variations.
COMBUSTION AND FLAME
(2022)
Article
Energy & Fuels
Yakun Zhang, Stephanie A. Coronel, Remy Mevel
Summary: This study presents the performances of four commonly-used extrapolation models, investigates the effects of experimental limitations, and analyzes the model and noise errors in the overall extrapolation uncertainty. The study suggests using large experimental facilities and high camera framing rates to reduce noise error, and recommends selecting the model that best reproduces flame propagation for extrapolation to zero-stretch. The procedures developed in this study can be used to predict extrapolation-induced error and optimize laminar flame speed experiments.
Article
Chemistry, Physical
Haoxin Deng, Zhifeng Yao, Guoyan Chen, Xiaoping Wen, Fahui Wang, Qiaosheng Zhang, Jianfei Dong, Mingming Huang
Summary: This study investigates the effect of laminar flame speed on flame dynamics in two-dimensional half open tubes using a two-dimensional laminar combustion model. The simulation results reveal that flame propagation similarity is only maintained during the acceleration phase, with flame tip velocity oscillation being related to the laminar flame speed. The correlation between flame surface area and the growth rate of burnt gas volume is also influenced by laminar flame speed.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Thermodynamics
Yakun Zhang, Marine Jeanson, Remy Mevel, Zheng Chen, Nabiha Chaumeix
Summary: This study utilized the flame stability theory of Matalon to adjust mixture properties for the onset of cellular flame at a predetermined large radius, showing that uncertainty in critical flame radius calculation mainly comes from fundamental transport and kinetic data. Despite the accuracy of the tailored flame speed measurement, inaccurate parameters can lead to significantly over-estimated critical radius for cellular flame onset. The use of unsteady 1-D simulations with various chemical mechanisms demonstrated the characterization of unstretched laminar flame speed with relative error below 10% for most conditions, while capturing flame dynamical response to stretch rate only under specific conditions.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
F. Halter, G. Dayma, Z. Serinyel, P. Dagaut, C. Chauveau
Summary: The experimental difficulties of obtaining flame speed data under specific thermodynamic conditions may be overcome by using the constant volume method for spherically expanding flames. By integrating experimental and numerical approaches, key reactions can be identified and kinetic schemes can be tested over a wide range of pressure and temperature domains with good accuracy. The use of a new experimental device allows for simultaneous recording of pressure and flame radius, providing valuable information for improving combustion processes.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Mattias A. Turner, Tyler T. Paschal, Pradeep Parajuli, Waruna D. Kulatilaka, Eric L. Petersen
Summary: A high-speed chemiluminescence imaging diagnostic system has been developed to measure flame properties, showing excellent agreement between experimental results and literature values. The study found no significant differences in flame speeds or Markstein lengths derived from different emission wavelength bands. This implies that multiple flame properties can be acquired simultaneously using this method.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2021)
Article
Thermodynamics
Shinichi Asano, Akira Yoshida
Summary: The study investigates the effect of water mist on the liftoff and blowout of a propane/air coflowing diffusion flame. It was found that water mist deteriorates the stability of the flame, leading to blowout, while stability of the lifted flame depends on the dynamic balance between local mean gas velocity and mean turbulent flame propagation speed.
COMBUSTION AND FLAME
(2021)
Article
Energy & Fuels
R. Rabello de Castro, P. Brequigny, J. P. Dufitumukiza, C. Mounaim-Rousselle
Summary: Syngas, a gaseous biofuel, requires operation mode adaptation when used for stationary electricity generation in Internal Combustion engines. Research indicates that combustion parameters of different syngas compositions from various gasifiers affect flame speeds, with Updraft and Downdraft compositions showing higher speeds. Kinetic modeling results show good overall agreement with experimental data, with CRECK mechanism deviating by only 5-10%.
Article
Thermodynamics
Xue Gong, Qing Xie, Hua Zhou, Zhuyin Ren
Summary: The study found that the propagation speed increases significantly for large residence times, but for fuels with strong low temperature chemistry, the propagation speed may first increase slightly at relatively small residence times. The trajectories of autoignition-assisted flames rapidly converge to the autoignition trajectory as the propagation speed increases. The balance in the high temperature reaction zone transitions from reaction-diffusion to reaction-convection as the propagation speed increases, demonstrating the shift from flame propagation to autoignition.
COMBUSTION AND FLAME
(2022)
Article
Energy & Fuels
Zhipeng Yuan, Linming Xie, Xingyu Sun, Rumin Wang, Huaqin Li, Jingping Liu, Xiongbo Duan
Summary: This paper numerically simulated the effects of water vapor on the auto-ignition characteristics and laminar flame speed of the methane/air mixture. The results showed that the ignition delay time of the methane/air increased with increasing water vapor ratio, and the laminar flame speed and adiabatic combustion temperature decreased as well.
Article
Thermodynamics
Yifan Yang, Haodong Zhang, Linye Li, Mingming Gu, Xi Xia, Fei Qi
Summary: This paper investigates the formation of a blue whirl by controlling tangential and radial airflows. By using a unique fire whirl apparatus, the blue whirl can be formed directly upon ignition without going through the transient phase. The study also discovers new flame regimes and explores the mechanism behind the formation and transition of the blue whirl.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Xiaobin Qi, Songyan Gao, Zhiping Zhu, Qinggang Lyu, Haixia Zhang
Summary: This study experimentally investigated the propagation characteristics of reverse combustion under oxygen-limited and enriched conditions. The contribution of volatiles gas-phase oxidation and char surface oxidation to reverse combustion was evaluated. The results showed that oxygen enrichment expanded the operating range of oxygen flow rate for reverse combustion and enhanced the low-temperature oxidation of the solid fuel. The findings provide a better understanding of the driving mechanism of reverse combustion and have important implications for efficient thermal conversion of solid fuels.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Bingjie Chen, Peng Liu, Bingzhi Liu, Zhandong Wang, Xiang Gao, William L. Roberts
Summary: In this study, the low temperature oxidation of 1,2,4-trimethylbenzene was investigated using experiments and numerical simulations. The results showed the presence of toxic oxygenated aromatic compounds and proposed potential formation pathways. The numerical simulations accurately predicted the mole fractions of most compounds, but some compounds were missing.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Meng Sui, Zhiheng Zhu, Fashe Li, Hua Wang
Summary: The effect of adding ferrocene as a combustion catalyst to Jatropha biodiesel on its pyrolysis and combustion performance is investigated. The results show that adding ferrocene reduces activation energy and harmful emissions while improving combustion efficiency.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Manaf Sheyyab, Mohammed Abdulrahman, Subharaj Hossain, Patrick T. Lynch, Eric K. Mayhew, Kenneth Brezinsky
Summary: Fuel surrogates, simplified representations of complex fuels, accurately model speciation results and reaction kinetics, reproduce the ignition quality and chemical functional group compositions of their parent fuels.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Yan Wang, Shumeng Xie, Hannes Bottler, Yiqing Wang, Xinyi Chen, Arne Scholtissek, Christian Hasse, Zheng Chen
Summary: This study investigates how flow affects the ignition and transition process of a cool flame. The results show that the ignition energy determines the highest temperature and the strain rate influences the flame propagation and the transition from cool flame to hot flame.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Tanusree Chatterjee, Mengyuan Wang, Goutham Kukkadapu, Chih-Jen Sung, William J. Pitz
Summary: Cycloalkanes, including cyclohexane, are important hydrocarbons in transportation fuels. However, limited oxidation data at low-to-intermediate temperatures and inadequate predictive ability of kinetic models have hindered the understanding and improvement of cyclohexane oxidation. This study provides experimental and modeling results to develop a more accurate kinetic model for cyclohexane oxidation.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Tao Wu, Erik Hagen, Haiyang Wang, Dylan J. Kline, Michael R. Zachariah, Carole Rossi
Summary: It was found that incorporating CuO into Al/I2O5 can significantly reduce the ignition time and enhance the combustion performance. The optimum composition of 80/20 wt% of I2O5/CuO shows a 30 times shorter ignition time and produces a peak pressure and pressurization rate 4 and 26 times greater than traditional Al/I2O5. A series of characterizations helped unravel the cause of improvement and propose a reaction mechanism for this ternary Al/I2O5/CuO system. This study proposes a facile, inexpensive, and efficient way to enhance the combustion performance of Al/I2O5 biocidal nanoenergetic materials.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Mahmoud Gadalla, Shervin Karimkashi, Islam Kabil, Ossi Kaario, Tianfeng Lu, Ville Vuorinen
Summary: In this study, the flame initiation process in dual-fuel spray assisted combustion is explored through scale-resolved simulations, providing numerical evidence on the initiation of premixed flames. It is found that there is a transient mixed-mode combustion phase after ignition, followed by a primarily deflagrative combustion mode. The interactions between turbulence and premixed flame front are characterized in the corrugated regime.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Neeraj Kumar Pradhan, Arindrajit Chowdhury, Debasis Chakraborty, Neeraj Kumbhakarna
Summary: In this study, a modified model for predicting the burn rate of composite solid propellants is proposed. The model has been validated against experimental and theoretical results, and it outperforms existing models in all cases considered. The model is highly robust and provides results quickly, making it highly efficient in terms of time, effort, and computational resources.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Lili Ye, Zhihe Zhang, Fan Wang, Xiaodong Wang, Yiming Lu, Lei Zhang
Summary: This study investigated the pyrolysis mechanism of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) explosive using ab initio and kinetic modeling simulations. The results showed that N-NO2 bond fission and C-H beta-scission are important channels in the decomposition of HMX.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Andrei N. Lipatnikov, Hsuchew Lee, Peng Dai, Minping Wan, Vladimir A. Sabelnikov
Summary: This study investigates the importance of thermodiffusive and hydrodynamic instabilities of laminar flames in turbulent flows through numerical simulations. The analysis suggests that laminar flame instabilities play a minor role at sufficiently high Karlovitz numbers.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Shijie Xu, Yue Qiu, Leilei Xu, Jianqing Huang, Shen Li, Elna J. K. Nilsson, Zhongshan Li, Weiwei Cai, Marcus Alden, Xue-Song Bai
Summary: Metal powder is a promising carbon-free and recyclable energy carrier. In this study, a computational model for the combustion and phase change of micron-sized iron particles was proposed and validated. The model successfully captures the melting, surface reactions, cooling, and solidification processes. The study also reveals a two-stage solidification phenomenon and identifies a diffusion-controlled mechanism during the melting process. The reaction between iron and CH4/O2/N2 flame products is found to play a significant role in the iron combustion process.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Khalid Aljohani, Abd El-Sabor Mohamed, Haitao Lu, Henry J. Curran, S. Mani Sarathy, Aamir Farooq
Summary: This study investigates the impact of exhaust gas recirculation (EGR) and NOx on the ignition delay time of oxygenated gasoline. A gasoline surrogate model is developed and the experimental data are useful for predicting fuel ignition behavior in internal combustion engines. The results show that EGR inhibits gasoline reactivity, while NOx has a promoting effect at high temperatures. This research is important for understanding the combustion behavior of gasoline in engines.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Chengcheng Ao, Jia Yan, Tong Yan, Lidong Zhang, Pan Wang
Summary: This study investigates the inhibitory effect of ammonia blended with hydrocarbon fuels on soot formation. The results show that there is a chemical interaction between ammonia and polycyclic aromatic hydrocarbons (PAHs), blocking the formation of larger PAHs.
COMBUSTION AND FLAME
(2024)