Article
Thermodynamics
S. K. Thirumalaikumaran, Gautham Vadlamudi, Saptarshi Basu
Summary: This study investigates the interaction between incident vortex and buoyant diffusion flame. The flame response depends on the vortex strength, and different response regimes are identified. The high-velocity scales imposed during vortex interaction make the flow momentum-dominant, resulting in forward extinction and flame lift-off. The estimation of flame shedding height requires consideration of vortex circulation and velocity scale.
COMBUSTION AND FLAME
(2022)
Article
Physics, Applied
Xiaoyu Ju, Anek Bunkwang, Takuya Yamazaki, Tsuneyoshi Matsuoka, Yuji Nakamura
Summary: This paper presents a method to suppress flame flickering without changing the burning rate of fuel. By horizontally reciprocating one burner in a dual burner system, a death mode can be generated around the critical burner separation distance. The criterion to obtain a complete death mode region in a dual burner system is defined by two dimensionless parameters.
PHYSICAL REVIEW APPLIED
(2023)
Article
Energy & Fuels
Changfa Tao, Bin Liu, Yuling Dou, Yejian Qian, Yu Zhang, Shun Meng
Summary: The study examined the flame height and lift-off height of a turbulent jet diffusion flame under different conditions. Experimental results showed that the flame height initially increased and then decreased with an increase in CO2 concentration, while the lift-off height increased with CO2 concentration.
Article
Thermodynamics
Ahmad Sayed-Kassem, Pascale Gillon, Mahmoud Idir, Virginie Gilard
Summary: This study investigates the flickering instability of methane and ethylene flames and explores the use of a mechanical stabilizer to control it. The experiment reveals that the flickering frequency is independent of the fuel jet velocity and can be suppressed by only controlling the air surrounding the flame.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Physics, Fluids & Plasmas
Yuki Araya, Hiroaki Ito, Hiroyuki Kitahata
Summary: This study investigates the bifurcation structure of flame oscillations through simulation and experiment. The results show that the flame can switch between stationary and oscillatory states, with the amplitude and frequency controlled by the fuel-inlet diameter. The study also discusses the impact of vortices on flame dynamics.
Article
Thermodynamics
Yicheng Chi, Tao Yang, Peng Zhang
Summary: This study experimentally investigates a nonlinear dynamic system of triple flickering buoyant diffusion flames in an isosceles triangle arrangement. The study focuses on establishing a controlled gas-fuel diffusion flame experiment and developing a Wasserstein-space-based methodology for dynamical mode recognition. Seven distinct stable dynamical modes are identified using this experiment and methodology.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Yubo Bi, Jiaqi Wang, Haidong Liu, Shenshi Huang, Shouxiang Lu, Zhian Yang, Haiyong Cong, Lili Ye, Mingshu Bi
Summary: This paper experimentally investigated the combustion characteristics of a rectangular ethylene jet flame under different flow rates and nozzle aspect ratios. The results showed that the flame height and oscillation frequency were affected by the aspect ratio, with both decreasing as the aspect ratio increased. The radiant heat flux also varied with the aspect ratio, depending on the ethylene flow rate.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Thermodynamics
Huaxian Wan, Xinyi Liu, Yuchun Zhang
Summary: This study aims to investigate the flame height of two unequal buoyant turbulent diffusion flames and establish correlations and equations based on flame merging. The accuracy of the proposed model is validated using experimental data and the application scope is expanded to the flame height in merging state of two identical fires.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Energy & Fuels
Meiyu Shi, Xudong Song, Weiguang Su, Juntao Wei, Peng Lv, Jianrong Yang, Guangsuo Yu
Summary: The stability of CH4/O2 inverse diffusion impinging flame is studied using OH* chemiluminescence diagnosis in this study. The effects of different nozzle incidence angles and the impinging distance on the stability of impinging flame and OH* chemiluminescence are investigated. The obtained results show that the flame root of the 45 degrees nozzle breaks and makes noise near the blowout, the lift-off limit has a linear correlation with the impinging distance. It is found that the 90 degrees nozzle has the maximum lift-off limit, the 45 degrees nozzle has the maximum blowout limit. When the impinging distance is more than 20 mm, the lift-off state does not occur for the 60 degrees nozzle. The flame is in the attachment state, the OH* chemiluminescence of the three nozzles enhances as the oxygen flow rate increases. The radial distribution of OH* radicals shows that the peak intensity of the flame decreases with decreasing nozzle incidence angle. The position of the core area of 45 degrees and 60 degrees nozzles increases with the increase of oxygen flow rate. Meanwhile, the position of the reaction core area of the 90 degrees nozzle increases with the oxygen flow rate in the attachment state and decreases monotonically in the lift-off state.
Article
Energy & Fuels
Xiepeng Sun, Xiaolei Zhang, Jiang Lv, Xiaotao Chen, Longhua Hu
Summary: This work studies the characteristics of buoyant turbulent diffusion flames considering different flame intermittent levels and mean flame projection area. Experimental data and models are proposed to describe the behavior of the flame height and flame projection area. The results show that the mean flame height decreases with increasing burner area, and the flame height decreases with lower intermittent levels.
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
Chemistry, Physical
Sanghyeok Kwak, Jaehong Choi, Myunggeun Ahn, Youngbin Yoon
Summary: The effects of hydrogen addition on the forced response of H-2/CH4 flames in a dual-nozzle swirl-stabilized combustor are analyzed. The study shows that the flame transfer function (FTF) characteristics are determined by the change in flame angle and the flame roll-up phenomenon, with the latter playing a more important role. In addition, hydrogen addition attenuates the local maximum gains and decreases the FTF phase slope. These differences are primarily attributed to the change in flame roll-up behavior induced by a short and compact flame distribution at high hydrogen contents.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Engineering, Civil
Kaiyuan Li, Zhuangzhuang Ma, Xinyan Huang, Yanyan Zou
Summary: This study investigates the merging characteristics of two identical linear diffusion flames, finding that the merging probability and merging flame height are related to flame spacing and heat release rate. A new dimensionless heat release rate parameter is proposed, and it is observed that decreasing entrained air from the ground facilitates flame merging. The merging flame height is determined by the competition of buoyancy and pressure difference, and can be correlated with the effective entrainment perimeter and dimensionless heat release rate.
FIRE SAFETY JOURNAL
(2022)
Article
Chemistry, Physical
Tananop Piemsinlapakunchon, Manosh C. Paul
Summary: This study presents a numerical investigation on the critical roles played by the chemical compositions of syngas on laminar diffusion flame instabilities. Different flame phenomena are formulated by varying the syngas fuel rate, and the consequence of each species in the syngas composition is explored. It is found that the ratio of H-2:CO, as well as the inclusion of CO, CH4, CO2, and N-2, significantly affect the instability level and heat generation fluctuation of the flame.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Automation & Control Systems
Jiabao Yang, Shuai Yan, Yan Gong, Qinghua Guo, Lu Ding, Guangsuo Yu
Summary: Dynamic Mode Decomposition (DMD) is a data-driven analysis method that has good prospects in combustion diagnostics using optical methods. In this study, the self-pulsation combustion instability of a four-burner impinging diesel flame was investigated using DMD analysis. The spatiotemporal evolution of the flame structure in the jet zone was studied, and the vortex evolution and oscillations in reaction intensity were analyzed. The high growth factor modes accurately identified the oscillation components in different flame structures and corresponded well with the grayscale image, although the local components may have different time scales in the DMD mode.
CONTROL ENGINEERING PRACTICE
(2023)
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)
