Article
Engineering, Aerospace
Kun Wu, Peng Zhang, Xuejun Fan
Summary: This study presented a three-dimensional hybrid LES/RANS approach to investigate jet-wake flame stabilization in a hydrogen-fueled dual-mode scramjet under high inflow stagnation temperature. The results showed that flame stabilization can be divided into different regions based on chemical kinetic and fluid dynamic perspectives.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Thermodynamics
Nikhil A. Baraiya, Vikram Ramanan, Baladandayuthapani Nagarajan, Chetankumar S. Vegad, S. R. Chakravarthy
Summary: This experimental study investigates the transition in syngas combustion dynamics from low-to high-frequency thermo-acoustic instability by continuously varying the Reynolds number (Re). Simultaneous OH* and CO2* chemiluminescence images were acquired to understand the role of flame dynamics in the transition. Further analysis was performed to identify the most driving regions of the chemiluminescence maps and establish a correlation between those regions and flame regions receptive to positive coupling with acoustics. The results showed a convex shape growth rate variation in the OH* chemiluminescence map during the transition to high-frequency instability, while the CO2* chemiluminescence displayed a bi-modal variation, confirming the physical mechanism underlying the high-frequency oscillations.
Article
Chemistry, Physical
Yue Li, Gonglong Tang, Lin Ji, Dan Zhao
Summary: Chemical kinetics plays a crucial role in power generation and gas turbine combustion systems, with the proposal of a chemical delay model shedding light on the time delays between concentration evolution and unsteady heat release. Further studies reveal the presence of a thermokinetic feedback loop as a key driving mechanism for self-sustained unsteady heat release.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Thermodynamics
Federica Ferraro, Yipeng Ge, Michael Pfitzner, Matthew J. Cleary
Summary: A novel hybrid modeling approach combining LES and RANS-PDF methods has been successfully applied to turbulent non-premixed reacting flows, reducing computational effort while maintaining accuracy and consistency. By establishing a two-way coupling between the LES flow-field and the conditional composition RANS-PDF, the method shows good predictions and overall decrease of computational effort up to two orders of magnitude compared to experimental data.
COMBUSTION SCIENCE AND TECHNOLOGY
(2021)
Article
Thermodynamics
Xu Wen, Federica Ferraro, Hendrik Nicolai, Nozomu Hashimoto, Jun Hayashi, Noriaki Nakatsuka, Kazuki Tainaka, Christian Hasse
Summary: Large-eddy simulation (LES) with a detailed model was used to study a turbulent pulverized coal flame and characterize the soot evolution. A flamelet model was employed to describe the gas phase kinetics, and a quadrature-based moment method (QBMM) was used to describe the soot statistics considering various physicochemical processes. The simulation results were compared to experimental data, and good agreement was observed for various measurements such as PAHs-LIF, soot-LII, and SEM images. The contributions of different physicochemical processes to soot growth were quantified, with chemical surface growth being identified as the most important.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Engineering, Aerospace
Pradeep Kumar Pavalavanni, Min-Seon Jo, Jae-Eun Kim, Jeong-Yeol Choi
Summary: This study numerically investigates an unstable shock-induced combustion (SIC) case that exhibits regular oscillation experimentally. Detailed comparison of H-2/O-2 reaction mechanisms is made for the numerical simulation of SIC, highlighting the sensitivity of specific mechanisms to grid resolution and the generation of spurious reactions. The analysis reveals that the high-temperature reactions trigger instability in the oscillating flow field, disrupting the regularly oscillating mechanism by strengthening the reflecting compression wave and pushing the shock wave further.
Article
Thermodynamics
Lalit Patidar, Navin Fogla, Kevin Roggendorf, Syed Wahiduzzaman
Summary: To reduce emissions from internal combustion engines, this study develops a tabulated chemistry solver to reduce computational time by pre-calculating and storing the thermochemical states of the mixture. This method can be applied to engine design, optimization, and calibration.
INTERNATIONAL JOURNAL OF ENGINE RESEARCH
(2023)
Article
Energy & Fuels
A. Mark Payne, Kevin A. Spiekermann, William H. Green
Summary: Many technologically important systems involve complex product mixtures and reaction networks, making it challenging to build accurate reaction mechanisms. In this study, a model was developed to predict major and minor products in a three-component mixture with high accuracy.
Article
Engineering, Aerospace
V. F. Nikitin, E. V. Mikhalchenko, L. I. Stamov
Summary: A three-dimensional numerical simulation of a combustion chamber with a continuous rotating detonation wave was conducted. Different fuel mixtures were considered, and the traction characteristics were calculated. The results showed that a detonation mode was obtained for all feeding options.
Article
Computer Science, Interdisciplinary Applications
Magnus Furst, Andrea Bertolino, Alberto Cuoci, Tiziano Faravelli, Alessio Frassoldati, Alessandro Parente
Summary: An adaptable chemical kinetics optimization toolbox has been developed in this work, which can handle a large number of uncertain parameters and utilize various optimization methodologies. The toolbox is capable of handling experimental targets from different sources, showcasing its versatility in predicting chemical reactions.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Thermodynamics
Chiara Saggese, Charlotte M. Thomas, Scott W. Wagnon, Goutham Kukkadapu, Song Cheng, Dongil Kang, S. Scott Goldsborough, William J. Pitz
Summary: In this study, an improved kinetic model was developed based on theoretical calculations to enhance understanding of ignition and combustion behavior of C3-C4 alcohols and their blends with gasoline under engine-relevant conditions. The model demonstrated high accuracy in predicting ignition delay times and reactivity variations, highlighting its potential for application in boosted spark-ignition engines.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Mechanics
J. Kuhlmann, S. Marragou, I. Boxx, T. Schuller, W. Polifke
Summary: This study combines Large Eddy Simulation (LES) with System Identification (SI) to determine the Flame Transfer Functions (FTFs) of technically premixed flames. Two different approaches are used to obtain the corresponding FTFs from numerical data and compare them with experimental results. The experiment measures CH* chemiluminescence instead of heat release rate, which is insufficient for FTF identification but can be used for simulation validation. The LES/SI approach is shown to be flexible and reliable for technically premixed flames.
Article
Chemistry, Physical
Yunqiu Xia, Youjun Lu
Summary: This study evaluated the flammability and stability of hydrogen hydrothermal combustion using detailed chemical kinetics and simulations. The results show that pure hydrogen is difficult to burn in supercritical water, but CO2 can reduce the ignition delay time and ignition temperature of hydrogen. Compared to gas combustion, hydrogen hydrothermal combustion has a lower ignition temperature.
JOURNAL OF SUPERCRITICAL FLUIDS
(2022)
Article
Energy & Fuels
Andrey V. Minakov, Viktor A. Kuznetsov, Artem A. Dekterev, Igor S. Anufriev, Evgeny P. Kopyev, Sergey V. Alekseenko
Summary: Currently, thermal power plants are one of the main sources of electricity, but the combustion of fossil fuels produces harmful emissions. Injecting steam into the combustion chamber is an effective method to suppress these emissions. The influence of various mathematical submodels on the accuracy of the numerical simulation of fuel combustion was studied, and the best submodels were determined through comparison with experimental data. Using the EDC model with a mechanism consisting of 60 components and 305 elementary reactions resulted in the highest agreement with experimental data.
Article
Energy & Fuels
Yushuai Liu, Yannis Hardalupas, Alexander M. K. P. Taylor
Summary: A new detailed kinetic model for CO2(1B2) chemiluminescence has been proposed, which successfully predicts the chemiluminescent intensity in hydrocarbon flames and shows good agreement with experimental data. The model extends knowledge of CO2(1B2) chemistry by reproducing a wide range of experimental data.
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)