Article
Thermodynamics
Kendyl A. Waddell, Han Ju Lee, Vedha Nayagam, Richard L. Axelbaum, Peter B. Sunderland
Summary: A new method is presented for observing cool diffusion flames inexpensively using a pool of liquid n-heptane and heated parallel plates. This is the first observation of cool flames burning near the surfaces of fuel pools. The measured peak temperatures were between 705 and 760 K, 70 K above the temperature of the surrounding air, with autoignition first occurring at 550 K.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Yiguang Ju
Summary: Low-temperature flames, including cool flames, warm flames, double flames, and auto-ignition assisted flames, play a critical role in advanced engines and fuel design. Research on their structures, dynamics, and combustion limits is important for future engine development. Additionally, using low temperature flames to validate chemical kinetic models of alternative fuels is a novel research direction.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Thomas Panaget, Killyan Potier, Sebastien Batut, Amaury Lahccen, Yann Fenard, Laure Pillier, Guillaume Vanhove
Summary: Cool flames of diethyl ether were studied in a stagnation plate burner under different conditions. Ozone-seeding was added to stabilize a lean cool flame, and a stoichiometric flame was also studied without ozone addition. The positions and products distribution of the cool flame were measured using chemiluminescence and detailed kinetic models were used to improve the understanding of the low temperature kinetics and ozone influence. The results showed the importance of R<(O)over dot> radical decomposition and its link to atmospheric chemistry and low temperature combustion.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
D. L. Dietrich, J. S. T'ien
Summary: This paper discusses the possibility of brief cool flame burning of microgravity candle flames after hot-flame extinction. While there is no direct evidence to confirm this phenomenon, there is indirect evidence that suggests it may have occurred.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
R. Schiessl, V Bykov
Summary: In this study, ridge analysis is applied to characterize reaction zones in non-premixed combustion, and the effectiveness of the method is explored in three-dimensional simulation data. The results demonstrate that ridge analysis can accurately locate and describe the characteristics of reaction zones, and reveal different types of reaction zone geometries.
COMBUSTION AND FLAME
(2022)
Article
Energy & Fuels
Yuzhou Cheng, Tai Jin, Kun Luo, Zongyan Li, Haiou Wang, Jianren Fan
Summary: The combustion instability in laminar premixed flames is influenced by flame holder temperature, with different instability modes at different temperatures being affected by flame characteristics, recirculation zones, and acoustic modes. ITA modes affect combustion instability in different ways, either causing intrinsic instability or coupling with acoustic modes to create new instability modes, highlighting the importance of considering ITA modes in the analysis of combustion instability in realistic systems.
Article
Thermodynamics
Minhyeng Kim, Kendyl A. Waddell, Peter B. Sunderland, Vedha Nayagam, Dennis P. Stocker, Daniel L. Dietrich, Yiguang Ju, Forman A. Williams, Phillip Irace, Richard L. Axelbaum
Summary: An improved understanding of cool diffusion flames, investigated in the microgravity environment of the International Space Station using a spherical porous burner, has the potential to enhance engine performance. The experiments included various fuel and oxygen concentrations, pressures, and flow rates, and utilized diagnostics such as intensified video cameras, radiometers, and thermocouples. The results revealed the presence of spherical cool diffusion flames, with particular conditions required for their production, and highlighted the significance of burner temperature and rich regions near a mixture fraction of 0.53.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Keisuke Akita, Youhi Morii, Hisashi Nakamura, Takuya Tezuka, Kaoru Maruta
Summary: The study utilized numerical simulation to reproduce flames with repetitive extinction and ignition in a micro flow reactor. It was found that the ignition of hot flames originated from residual CO in the previous cycle, and several heat release rate peaks related to different flames were observed between extinction and ignition locations.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Matthew Q. Brown, Erica L. Belmont
Summary: The study investigated the effects of ozone enhancement on n-heptane cool flames through experimental and numerical assessments. The results showed that ozone impacts low temperature kinetics and affects low temperature ignition and cool flames.
COMBUSTION AND FLAME
(2021)
Article
Engineering, Aerospace
Andrej Sternin, Daniel Martinez, Daniel Sternin, Oskar Haidn, Martin Tajmar
Summary: This work aims to provide support for the design of reliable DNSs for statistically planar flames. Improved simulation design strategies are developed, as well as a deterministic calculation strategy for mesh features. Guidelines and measurement techniques are proposed for choosing design parameter values and determining characteristic points within the flame front.
Article
Thermodynamics
Shenghui Zhong, Shijie Xu, Fan Zhang, Zhijun Peng, Longfei Chen, Xue-Song Bai
Summary: This study investigates the impact of cool flame on spray ignition and flame stabilization in low-temperature combustion engines. The results show that cool flame promotes the ignition of fuel-rich and cold reactant mixtures and leads to a shift of the most reactive mixture towards fuel-richer locations. The propagation of cool flame is influenced by temperature and concentration stratification and turbulent mixing. The findings also suggest that cool flame is more significant at lower ambient temperatures.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Engineering, Aerospace
Daniel Martinez-Sanchis, Andrej Sternin, Oskar Haidn, Martin Tajmar
Summary: Direct numerical simulations are used to investigate the turbulent mixing burning of fuel-rich methane-oxygen flames in rocket engines. The results show that a significant amount of premixed combustion occurs in the non-premixed configuration, and turbulence increases the fraction of propellants burnt in oxygen-rich and near-stoichiometric conditions, influencing combustion completion at downstream positions.
Article
Thermodynamics
A. N. Lipatnikov, V. A. Sabelnikov
Summary: The study analyzes DNS data from a lean, complex chemistry, hydrogen-air flame to examine three different models for evaluating mean concentrations of various species in turbulent combustion research. The best predictions are obtained by using a Probability Density Function to average species mole fractions and density directly from laminar-flame profiles. This approach proves useful for evaluating mean mole fractions of different species in turbulent flames.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Yuki Murakami, Christopher B. Reuter, Omar R. Yehia, Yiguang Ju
Summary: This study investigated autoignition-assisted nonpremixed cool flames of diethyl ether (DEE) in laminar counterflow and turbulent jet flame configurations. It was found that below a critical mixture condition, the cool flame extinction limit and the low-temperature ignition limit merge, leading to autoignition-assisted cool flame stabilization. Turbulent lifted cool flames were established based on findings from laminar flame experiments and a correlation was proposed for predicting the lift-off height of these flames.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Suryanarayan Ramachandran, Navneeth Srinivasan, Taaresh S. Taneja, Hongyuan Zhang, Suo Yang
Summary: This study investigates the formation of cool flames at high/supercritical pressures using AMR simulations. The results show that the increase in pressure leads to a decrease in the first stage ignition delay time and significant differences in the mixture-layer profiles.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Richard A. Messerly, Mohammad J. Rahimi, Peter C. St John, Jon H. Luecke, Ji-Woong Park, Nabila A. Huq, Thomas D. Foust, Tianfeng Lu, Bradley T. Zigler, Robert L. McCormick, Seonah Kim
COMBUSTION AND FLAME
(2020)
Article
Thermodynamics
Rui Xu, Chiara Saggese, Robert Lawson, Ashkan Movaghar, Thomas Parise, Jiankun Shao, Rishav Choudhary, Ji-Woong Park, Tianfeng Lu, Ronald K. Hanson, David F. Davidson, Fokion N. Egolfopoulos, Allen Aradi, Arjun Prakash, Vivek Raja Raj Mohan, Roger Cracknell, Hai Wang
COMBUSTION AND FLAME
(2020)
Article
Energy & Fuels
Chao Xu, Pinaki Pal, Xiao Ren, Magnus Sjoberg, Noah Van Dam, Yunchao Wu, Tianfeng Lu, Matthew McNenly, Sibendu Som
Summary: This study investigates lean mixed-mode combustion in a spark-ignition engine using CFD, developing a new E30 fuel surrogate and a skeletal mechanism with NOx submechanism. The CFD model accurately predicts pressure and AHRR traces, showing two distinct combustion cycles with early flame propagation and end-gas auto-ignition in mixed-mode cycles. NOx chemistry promotes auto-ignition through residual gas, while fuel properties like heat of vaporization and laminar flame speed have varying effects on combustion characteristics.
JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME
(2021)
Article
Energy & Fuels
Pinaki Pal, Krishna Kalvakala, Yunchao Wu, Matthew McNenly, Simon Lapointe, Russell Whitesides, Tianfeng Lu, Suresh K. Aggarwal, Sibendu Som
Summary: The study investigated the central fuel property hypothesis by determining if RON and MON are sufficient to describe a fuel's knock-limited performance. Fuel surrogates were created with matched RON and MON, and numerical simulations were performed to analyze their performance under boosted SI conditions. The research found that deviations in knock-limited performance could be caused by differences in laminar flame speed, but significant deviations from the octane index framework require large fuel-specific differences in LFS.
JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME
(2021)
Article
Thermodynamics
Alex Krisman, Patrick Meagher, Xinyu Zhao, Ji-Woong Park, Tianfeng Lu, Jacqueline H. Chen
Summary: This study investigates flame quenching mechanisms in aeronautical engines through numerical simulations, revealing flame shortening and high flame stretch as two extinction mechanisms, with local balance determining the propensity for local extinction.
COMBUSTION AND FLAME
(2021)
Article
Energy & Fuels
Krishna Kalvakala, Pinaki Pal, Yunchao Wu, Goutham Kukkadapu, Christopher Kolodziej, Jorge Pulpeiro Gonzalez, Muhammad Umer Waqas, Tianfeng Lu, Suresh K. Aggarwal, Sibendu Som
Summary: Growing environmental concerns and demand for better fuel economy are driving forces for advanced engine research. Multi-mode combustion strategies optimize engine performance by correlating different combustion modes with load operating conditions. Focus on ACI mode in the study shows potential benefits in terms of low fuel consumption, low NOx, and PM emissions. Various fuel effects on ACI combustion behavior are analyzed under different operating conditions, showing different sensitivities to fuel properties such as octane sensitivity (S) and Research Octane Number (RON).
JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME
(2021)
Article
Energy & Fuels
Sayop Kim, Riccardo Scarcelli, Yunchao Wu, Johannes Rohwer, Ashish Shah, Toby Rockstroh, Tianfeng Lu
Summary: The study explores the concept of multi-mode combustion using two RON98 gasoline fuel blends in a gasoline direct injection engine. The research characterizes primary combustion dynamics observed in ACI and SI combustion modes and validates it against experimental measurements to cover varying engine load demands for multi-mode engines.
JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME
(2021)
Article
Thermodynamics
Sophie Wang, Tianfeng Lu
Summary: A new spectral method is proposed for speeding up sensitivity analysis for ignition and extinction of perfectly stirred reactors by taking advantage of linear dependency in stoichiometric coefficient vectors. Compared to conventional methods, the new method reduces computational cost and is suitable for detailed chemical reaction mechanisms.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Yunchao Wu, Yang Gao, Tianfeng Lu
Summary: The AHI2 scheme proposes a dynamic adaptive hybrid integration method of second-order accuracy for time-integration of chemically reacting flows. It combines the midpoint scheme and the trapezoidal rule to achieve second-order accuracy, significantly improving accuracy compared with the AHI1 method. The AHI2 scheme can accurately predict extinction of unsteady perfectly stirred reactors, showing the necessity not to split the chemistry and transport source terms for prediction of extinction or forced-ignition problems involving significant radical sources.
COMBUSTION AND FLAME
(2021)
Article
Engineering, Mechanical
Sandeep Jella, Gilles Bourque, Pierre Gauthier, Philippe Versailles, Jeffrey Bergthorson, Ji-Woong Park, Tianfeng Lu, Snehashish Panigrahy, Henry Curran
Summary: To minimize auto-ignition risk in the design of premixers for high power aeroderivative gas turbines, consideration of low-temperature auto-ignition precursor chemistry is essential. Chemical explosive modes offer a comprehensive approach to assessing auto-ignition risk by integrating chemical and aerodynamic influences.
JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME
(2021)
Article
Thermodynamics
Ki Sung Jung, Seung Ook Kim, Tianfeng Lu, Jacqueline H. Chen, Chun Sang Yoo
Summary: The study investigates turbulent lifted hydrogen jet flames in heated coflows with temperatures ranging from 750 K to 1100 K, using a detailed H-2/air chemical mechanism. The results show that flame stabilization is primarily achieved through flame propagation rather than autoignition at 950 K, while at 1100 K, flame stabilization is highly affected by autoignition. Vortexes in the mixing layer between heated coflow and cold H-2 tend to retard autoignition within the vortex, especially when the temperature is slightly above the autoignition limit.
COMBUSTION AND FLAME
(2021)
Article
Chemistry, Multidisciplinary
Mostafa Raafat Kotob, Tianfeng Lu, Seddik S. Wahid
Summary: The study experimentally compared the effects of direct-water and -steam injections on NOx emission reduction, finding that both water and steam injections can effectively reduce NOx emissions with direct-water injection being more effective. The best inclination angle for both injections was found to be 45 degrees.
Proceedings Paper
Engineering, Mechanical
Sayop Kim, Joohan Kim, Ashish Shah, Pinaki Pal, Riccardo Scarcelli, Toby Rockstroh, Sibendu Som, Yunchao Wu, Tianfeng Lu
PROCEEDINGS OF THE ASME INTERNAL COMBUSTION ENGINE FALL TECHNICAL CONFERENCE, 2019
(2020)
Proceedings Paper
Engineering, Mechanical
Pinaki Pal, Krishna Kalvakala, Yunchao Wu, Matthew McNenly, Simon Lapointe, Russell Whitesides, Tianfeng Lu, Suresh K. Aggarwal, Sibendu Som
PROCEEDINGS OF THE ASME INTERNAL COMBUSTION ENGINE FALL TECHNICAL CONFERENCE, 2019
(2020)
Proceedings Paper
Engineering, Mechanical
Chao Xu, Pinaki Pal, Xiao Ren, Sibendu Som, Magnus Sjoberg, Noah Van Dam, Yunchao Wu, Tianfeng Lu, Matthew McNenly
PROCEEDINGS OF THE ASME INTERNAL COMBUSTION ENGINE FALL TECHNICAL CONFERENCE, 2019
(2020)
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)