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Kinetical driving force analysis of unstable combustion behavior in ammonia/hydrogen blending system Combust. Flame (IF 4.4) Pub Date : 2024-04-13 Mengze Ai, Shengyao Liang, Lin Ji, Dan Zhao
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Initiation process of non-premixed continuous rotating detonation wave through Schlieren visualization Combust. Flame (IF 4.4) Pub Date : 2024-04-11 Weijie Fan, Haoyang Peng, Shijie Liu, Mingbo Sun, Xueqiang Yuan, Hailong Zhang, Weidong Liu
High-speed schlieren visualization on the initiation process of non-premixed air and hydrogen continuous rotating detonation (CRD) is carried out in a well-designed rounded-rectangle hollow combustor in this study. The CRD initiation processes of pre-detonator ignition and spark plug ignition are comprehensively revealed by synchronous high-speed schlieren images and high-frequency dynamic pressure
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Spatiotemporally resolved surface temperature measurement of aluminum ignition and combustion in steam and oxygenated environments Combust. Flame (IF 4.4) Pub Date : 2024-04-09 Zhiyong Wu, Can Ruan, Mehdi Stiti, Shijie Xu, Xue-Song Bai, Edouard Berrocal, Marcus Aldén, Zhongshan Li
We report micrometric imaging measurements of the ignition of micron-sized aluminum (Al) wires and the consequent combustion processes of single micron-sized Al droplets in hot steam and steam with oxygen. The specially designed flames were anchored on a modified burner where a small central H/O diffusion flame in the center jet provided a hot flow (>2330 K) for Al ignition, and the diffusion flame
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Combustion Structure of a Cylindrical Rotating Detonation Engine with Liquid Ethanol and Nitrous Oxide Combust. Flame (IF 4.4) Pub Date : 2024-04-08 Tomoki Sato, Kotaro Nakata, Kazuki Ishihara, Noboru Itouyama, Ken Matsuoka, Jiro Kasahara, Akira Kawasaki, Daisuke Nakata, Hikaru Eguchi, Masaharu Uchiumi, Akiko Matsuo, Ikkoh Funaki
Liquid propellants are commonly used in rocket engines due to their high energy density. In this study, we focused on the use of liquid ethanol and liquid nitrous oxide as propellants in a cylindrical rotating detonation engine (RDE) for practical applications, and examined the effects of various conditions on the bipropellant RDE performance. We varied the vapor quality of nitrous oxide in a mixture
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Ab initio kinetics for H-atom abstraction from C1–C5 hydrocarbon and oxygenated species by CH3Ȯ radicals Combust. Flame (IF 4.4) Pub Date : 2024-04-08 Xuan Ren, Xin Bai, Mengmeng Jia, Shuyuan Liu, Yu Han, Ruoyue Tang, Song Cheng, Chong-Wen Zhou, Henry J. Curran, Yang Li
Hydrogen atom abstraction by methoxy (CHȮ) radicals plays an important role in gasoline/ethanol combustion chemistry. Detailed kinetic reactions for H-atom abstraction by CHȮ radicals from short carbon chain species, including alkanes, alkenes (including vinylic, allylic and diene), alkynes, ethers, ketones, and aldehydes is systematically studied in this work. The M06–2X/6–311++g(d,p) level of theory
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Combustion performance of aluminum modified boron nanoparticles coated with silane coupling agent Combust. Flame (IF 4.4) Pub Date : 2024-04-05 Tianyu Yang, Xiaoyan Qian, Jinyu Dai, Jun Liu, Jiuyu Chen, Jiaxin Wang, Minggao Xu, Yunlan Sun, Baozhong Zhu
Boron (B) powder, with its high mass and volumetric heat values, makes it highly promising in the field of energetic materials. However, the oxide layer on the B surface is the most significant barrier to realizing its full potential as a fuel. How to eliminate or disrupt the oxide layer is currently an urgent problem that needs to be addressed. This study proposes an approach to enhance the combustion
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Study on the combustion characteristics of NH3 and the inhibition characteristics of R134a on NH3 Combust. Flame (IF 4.4) Pub Date : 2024-04-04 Yongjie Shi, Rui Zhai, Yuan Zhuang, Xiangnong Liu, Siwei Tan, Shun Meng
NH has been considered as an alternative to hydrofluorocarbon (HFC) refrigerants due to its environmentally friendly properties, while it is flammable. Therefore, it is necessary to investigate the flammability of NH (R717) and find its matching flame retardant to broaden its application. In this paper, the combustion behaviors of R717 and the inhibition characteristics of flame retardant R134a on
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Investigation of thermodynamic state evolution, phase transition and mixing of the hydrocarbon droplet in convective supercritical environments Combust. Flame (IF 4.4) Pub Date : 2024-04-04 Yaquan Ai, Han Wu, Timothy Lee, Decan Zhu, Chia-fon Lee, Xiangrong Li
Liquid alkane droplets transit to supercritical fluids under supercritical conditions. However, the subsequent thermodynamic state evolution, phase transition, and mixing in this case, which directly influences combustion in actual diesel engines, need further investigation. We studied the thermodynamic state evolution, phase transition, and mixing of n-heptane droplets in supercritical laminar nitrogen
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Edge-flames in circular channels: Multiplicity of steady-state axisymmetric solutions Combust. Flame (IF 4.4) Pub Date : 2024-04-04 Vadim N. Kurdyumov, Carmen Jiménez
A numerical study of the combustion process occurring after separate injection of fuel and oxidizer through an end-wall porous plug into a semi-infinite circular channel is presented. The fuel flow is injected into the center of the channel, surrounded by the oxidizer flow in an axisymmetric manner. It is assumed that the channel walls and the porous plug are kept at constant (cold) temperature. The
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Pathological detonation in H[formula omitted]-Cl[formula omitted] mixtures: Uncertainty quantification and thermal non-equilibrium effects Combust. Flame (IF 4.4) Pub Date : 2024-04-04 Zituo Chen, Zifeng Weng, Xiangrong Huang, João Vargas, Rémy Mével
Pathological detonations are detonations with a propagation velocity higher than the classical Chapman–Jouguet velocity and which depends on the wave structure. Such a behavior has been experimentally observed in low-pressure hydrogen-chlorine mixtures and important discrepancies were reported between the experimental and the theoretical velocities. Using the steady planar detonation model, along with
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Particle-resolved hyperspectral pyrometry of metal particles Combust. Flame (IF 4.4) Pub Date : 2024-04-01 J. Hameete, M.S. Abdallah, L.C. Thijs, T.A.M. Homan, X.C. Mi, N.J. Dam, L.P.H. de Goey
We present temperature histories of individual combusting metal particles using hyperspectral pyrometry. This method gives an increase in accuracy over traditionally used two- or three-color pyrometry, while maintaining temporal and spatial resolution. Temperatures can be determined between 1800 to K with a precision of typically 1%. It is shown that the maximum temperature of the burning iron particles
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Low temperature oxidation chemistry of n-butylbenzene in n-decane/n-butylbenzene mixture: Product characterization and kinetic modeling study Combust. Flame (IF 4.4) Pub Date : 2024-03-29 Wenhao Yuan, Jijun Guo, Zaili Xiong, Yuwen Deng, Jigang Gao, Meirong Zeng, Jiuzhong Yang, Zhongyue Zhou, Fei Qi
-Alkanes and aromatics are two essential components in transportation fuels and have distinct oxidation reactivities. Due to products with different chemical functionalities generated in oxidation of -alkanes and aromatics, the interaction kinetics may significantly affect the overall reactivity as well as product distributions. This work investigated the oxidation chemistry of the mixture of -decane
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Formation of bubbles and microexplosions in burning boron agglomerates Combust. Flame (IF 4.4) Pub Date : 2024-03-27 Lian Duan, Zhixun Xia, Yunchao Feng, Binbin Chen, Jiarui Zhang, Likun Ma, Jianxin Hu
Combining laser ignition tests with quenched particle cross-sectional analyses, this study explores the formation of bubbles and microexplosions in burning boron agglomerates, and discusses the plausible mechanisms behind the microexplosion (expansion–rupture) phenomenon. High-resolution images reveal that these phenomena are caused by bubble nucleation and growth within the molten droplet. Based on
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Investigation of multi-scale flow structures and combustion characteristics in a cavity-enhanced circular scramjet Combust. Flame (IF 4.4) Pub Date : 2024-03-27 Tao Tang, Zhenguo Wang, Jiangfei Yu, Yuhui Huang, Mingbo Sun, Hongbo Wang, Guoyan Zhao, Yixin Yang, Dapeng Xiong
This study delves into the investigation of multi-scale flow structures and combustion characteristics in a cavity-enhanced circular scramjet operating under a Mach-4.5 freestream flow condition with a total temperature of 2200 K and a total pressure of 164 kPa. To achieve this, a hybrid large-eddy/Reynolds-averaged Navier-Stokes method, coupled with a pressure-corrected Flamelet/Progress Variable
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Nonlinear deflection tomography of inhomogeneous flame temperature and concentration based on topology evolution with prior smoothing Combust. Flame (IF 4.4) Pub Date : 2024-03-27 Zhi-Tian Niu, Hong Qi, Si Zheng, Ya-Tao Ren, Ming-Jian He, Fei Wang, Wen-Jun Sun
Tomographic absorption spectroscopy (TAS) is a promising temperature and concentration monitoring technology because it has fewer optical access requirements and species selectivity. However, the inhomogeneous distribution of temperature and species concentration in a practical reaction flow can cause laser deflection, which may affect the imaging quality. Thus, this study aimed to develop a novel
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Opposed jet burner and Tsuji burner for representative laminar flamelet with differential molecular diffusion for non-premixed combustion modeling Combust. Flame (IF 4.4) Pub Date : 2024-03-26 Tianfang Xie, Haifeng Wang
Modeling differential molecular diffusion in turbulent non-premixed combustion remains challenging for flamelet models. Laminar flamelet is a key building block of flamelet models for turbulent combustion. One significant challenge that has not been adequately addressed is the representativity of laminar flamelet for the characteristics of differential molecular diffusion in turbulent combustion. Laminar
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Detonation structure in the presence of mixture stratification using reaction-resolved simulations Combust. Flame (IF 4.4) Pub Date : 2024-03-26 Michael Ullman, Supraj Prakash, Shivam Barwey, Venkat Raman
Many investigations of detonation-based combustors have identified reactant mixture inhomogeneity as having a leading-order impact on wave dynamics and combustion efficiency. To examine this phenomenon in a simplified context, an array of two- and three-dimensional channel detonation simulations are conducted in the present work. The reactant mixture consists of stratified fuel and air, wherein the
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Laser-induced indirect ignition of non-premixed turbulent shear layers Combust. Flame (IF 4.4) Pub Date : 2024-03-26 Jonathan M. Wang, Mario Di Renzo, Gianluca Iaccarino, Hai Wang, Javier Urzay
This study uses direct numerical simulations to investigate the forced ignition of temporally-evolving turbulent subsonic shear layers separating a gaseous stream of methane (CH) and a stagnant gas environment of molecular oxygen (O). Ignition is forced by a thermal-energy source that heats up a small volume of gas during periods of time much shorter than the characteristic acoustic time scale. The
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Preparation of core-shell structured Al-5Li@HTPB powders with improved stability and combustion performance by using perfluoroalkylsilane as a surfactant Combust. Flame (IF 4.4) Pub Date : 2024-03-26 Jiabao Zhu, Shuo Wang, Weiqiang Xiong, Jun Wang, Xiaodong Li, Meishuai Zou
Aluminum-lithium alloy powder exhibits better thermal properties and combustion performances than aluminum, thus showing promising applications in the field of energetic materials such as explosives and propellants. However, the high activity of lithium also raises issues of stability and compatibility with propellant components, deteriorating the powder's overall performance. In this study, a facile
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On the difficulty of interpreting NO-LIF measurements around 226 nm in confined ammonia flames Combust. Flame (IF 4.4) Pub Date : 2024-03-25 Nour El Baba, Pascale Desgroux, Nathalie Lamoureux
This paper addresses how NH and NO absorption along the laser axis disrupts NO-LIF measurements made around 225 nm in NH/O/N premixed flames confined at low pressure (10 kPa). Measurements were performed in 3 flames (equivalence ratio = 0.87, 1.1 and 1.3) with 24 % N dilution. Together with the LIF measurements, single-pass absorption measurements were obtained in all flames as a function of the height
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Characteristics of laminar lifted flames of pure ethane in a non-premixed jet under various pressures Combust. Flame (IF 4.4) Pub Date : 2024-03-23 Gyu Jin Hwang, Dong Seok Jeon, Nam Il Kim
Recent studies have discovered that laminar lifted flames (LLFs) can be stabilized within a triangular stabilization regime (TSR), defined by the parameters of normalized lift-off height and Reynolds number. The stabilization mechanism of an LLF could be explained by using an effective Schmidt number over an extended pressure range. In this study, the existence of LLFs of pure ethane was confirmed
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Laser diagnostics in combustion and beyond dedicated to Prof. Marcus Aldén on his 70th birthday Combust. Flame (IF 4.4) Pub Date : 2024-03-21 Zhongshan Li, Christian Brackmann, Joakim Bood, Mattias Richter, Per-Erik Bengtsson, Katharina Kohse-Höinghaus
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Application of emission spectroscopy in plasma-assisted NH3/air combustion using nanosecond pulsed discharge Combust. Flame (IF 4.4) Pub Date : 2024-03-21 Jinguo Sun, Yupan Bao, Jonas Ravelid, Sebastian Nilsson, Alexander A. Konnov, Andreas Ehn
This work investigates the effects of atmospheric-pressure nanosecond (ns) pulsed plasma discharges on NH/air flames using optical emission spectroscopy (OES). Firstly, spatially-resolved OES in the 200–800 nm range of NH/air flames with and without discharges are presented to identify the plasma-induced excited species (such as N* and H*). Then, time-resolved OES with ns timescale resolution are achieved
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Evaluation of the thermo-acoustic instability frequency and growth rate via input reflection coefficient measurement for central heating equipment Combust. Flame (IF 4.4) Pub Date : 2024-03-20 Mohammad Kojourimanesh, Viktor Kornilov, Ines Lopez Arteaga, Philip de Goey
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Freestream and shear layer effects in bluff-body-stabilized turbulent premixed flames Combust. Flame (IF 4.4) Pub Date : 2024-03-20 Christopher A. Fugger, R.A. Forlines, Brendan T. Paxton, Andrew W. Caswell, Brent A. Rankin
The effects of low and high approach flow turbulence levels on a large-scale, confined, premixed bluff-body-stabilized flame are experimentally characterized. The flame and flow are imaged using simultaneous 10-kHz-rate formaldehyde (CHO) planar laser-induced fluorescence (PLIF), hydroxyl (OH) PLIF, particle image velocimetry (PIV), and OH* chemiluminescence. Elevated approach flow turbulence intensities
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Dynamic laser ignition characteristics of solid fuel and oxygen for hybrid rocket system Combust. Flame (IF 4.4) Pub Date : 2024-03-19 Hanqing Xia, Ningfei Wang, Jiantao Pang, Yi Wu
The transient laser ignition process in a slab burner that is similar to hybrid rocket motors is investigated in this study. The coupling characteristics between solid fuel properties, pyrolysis rate, and laser power were analysed. The results show that the laser ignition process can be divided into four stages: preheating, pyrolysis, ignition, and combustion, with the preheating and pyrolysis stages
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Dual-range emission spectroscopy for temperature measurement of laminar aluminum dust flames Combust. Flame (IF 4.4) Pub Date : 2024-03-19 Tao Yu, Kartik Mangalvedhe, Mathieu Francoeur, Jeffrey M. Bergthorson
Understanding the temperature fields/profiles in aluminum dust flames is critical to the design of aluminum-based sustainable fuels and the development of aluminum combustion simulation tools. Although emission spectroscopy has been applied in aluminum flames, the signals in most works were integrated along the recording path and over the whole flame and, therefore, the measurements could not provide
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Novel graphene iron organic nanocomposites for enhancing combustion and safety properties of AP-HTPB propellant Combust. Flame (IF 4.4) Pub Date : 2024-03-18 Ming Zhang, Fengqi Zhao, Jiankan Zhang, Ying Wang, Xueli Chen, Ting An, Zhao Qin, Haixia Hao
Graphene iron tannate and graphene iron gallate nanocomposites (G-D-Fe and G-M-Fe) were designed, synthesized and characterized to deal with the performance requirement of AP-HTPB propellent. Effects of the G-D-Fe and G-M-Fe on the thermal decomposition of AP, laser ignition, combustion and safety characteristics of AP-HTPB propellant were explored. By taking Catocene as the benchmark (156.80 mJ),
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Combustion and plume-plasma characteristics of cesium-based solid propellant Combust. Flame (IF 4.4) Pub Date : 2024-03-16 Zhiwen Wang, Hui Wang, Lian Li, Qianyi Zhang, Feng Li, Ruiqi Shen, Yinghua Ye, Wei Zhang
The high-temperature plume of solid propellant has spawned considerable amount of highly ionized plasma, which can be used to increase the specific impulse of propellant with the external physical field, as well as serve as the charged particles for the (MHD) generator on the thruster. Unfortunately, the deficiency of workable deal to promote the electrical performance of the plume hinders the development
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Influence of slit asymmetry on blow-off and flashback in methane/hydrogen laminar premixed burners Combust. Flame (IF 4.4) Pub Date : 2024-03-16 H. Pers, P.A. Masset, E. Flores-Montoya, L. Selle, T. Schuller
One way to decarbonize the heat production sector is to gradually replace natural gas with hydrogen. The design of laminar premixed burners capable of operating with both methane and hydrogen is however challenging as these fuels have drastically different burning properties, which narrows the operating range. While methane flames face limitations in stabilization due to blow-off at high power, hydrogen
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A detailed kinetic submechanism for OH[formula omitted] chemiluminescence in hydrogen combustion revisited. Part 2 Combust. Flame (IF 4.4) Pub Date : 2024-03-15 Alexander S. Sharipov, Boris I. Loukhovitski, Alexey V. Pelevkin, Mayya R. Korshunova
In this series of two papers, we present a novel physically sound kinetic submechanism aimed at modeling the formation and decay of chemiluminescent (electronically excited) OH molecules in the ignition and combustion of hydrogen and hydrogen-based mixtures over a wide range of temperatures and pressures. The present Part describes the construction of this detailed reaction submechanism based on the
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Near-limit detonation in long spiral tube: An improved experimental methodology and frequency analysis Combust. Flame (IF 4.4) Pub Date : 2024-03-15 Zhaoyuan Huang, Zihang Ni, Zongtai Li, Zifeng Weng, Damir Valiev, Rémy Mével
In the present work, near-limit detonations in near stoichiometric propane-oxygen mixtures were investigated using a long spiral tube facility. Compared to previous studies, our improvements in the tube length, framing rate and resolution, image processing methods for distortion correction and detonation front detection, allow for a significant increase of the amount and quality of data obtained. As
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Impact of multi-component description of hydrophilic fuel droplets in propagating spray flames Combust. Flame (IF 4.4) Pub Date : 2024-03-15 Fernando Luiz Sacomano Filho, Luís Eduardo de Albuquerque Paixão e Freire de Carvalho, Artur Carvalho Santos, Aymeric Vié, Jeroen Adrianus van Oijen
The need for an accurate description of the fuel composition is emerging in recently published studies on the interaction of droplets and flames. In this context, hydrophilic fuels are of particular importance, since they are expected to interact with the water formed during combustion reactions. The impact of such interactions onto the reaction process is still not explored enough. This work aims
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Combustion enhancement of boron-containing fuel-rich mixture by steam reforming in a supersonic flow Combust. Flame (IF 4.4) Pub Date : 2024-03-14 Chaolong Li, Weiguang Cai, Zhixun Xia, Likun Ma, Shu Zheng, Binbin Chen, Yunchao Feng, Jiarui Zhang
In this paper, a novel experimental investigation was conducted to enhance the combustion of boron-containing fuel-rich mixture by steam reforming in a supersonic flow. The ground direct-connected experiments were designed to simulate a flight condition at Mach number 5.9 and an altitude of 25 km. The operating characteristics and performance evaluation of the scramjet combustor were analyzed and discussed
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On the structure and dynamics of strong and weak eigenvalue detonation in condensed explosives Combust. Flame (IF 4.4) Pub Date : 2024-03-14 Vincent R. Schuetz, D. Scott Stewart
An eigenvalue detonation, also known as a pathological detonation, is a detonation with incomplete reaction at a point in the detonation reaction zone, that is sonic relative to the leading shock. Aluminized explosives are made by combining a molecular explosive with aluminum and other additives. During detonation, the molecular explosive’s first exothermic decomposition generates products that react
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Experimental study of ignition and combustion characteristics assisted by laser-induced plasma during oxy-coal atmosphere by optical emission spectroscopy Combust. Flame (IF 4.4) Pub Date : 2024-03-14 Wenkun Zhu, Mengfan Yuan, Xiaohui Li, Long Gao, Yonghong Yan, Jiangbo Peng, Zhuozhi Wang, Wenbei Liu, Rui Sun
This investigation aims to understand the enhancement characteristics of plasma-assisted combustion in oxy-coal combustion. A 1064 nm Nd:YAG laser was added into a laminar flow reactor to produce laser-induced plasmas (LIPs). The high-speed visualization of the coal flame was used to reveal combustion's progress and evolution following laser-induced breakdown. To the best of our knowledge, this is
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Phenomenological regression rate model in axial injection end-burning hybrid rocket motor using different oxidizers Combust. Flame (IF 4.4) Pub Date : 2024-03-14 Giuseppe Gallo, Mai Fukada, Sho Suzuki, Harunori Nagata
Compared with conventional configurations, axial-injection end-burning hybrid rocket motors work with multiport fuel grains, which mainly burn in the axial direction. The consumption rate is controlled by the several flames developed at the end of each port. Although many studies of performance and flame stability have been carried out in the past, a phenomenological model of the axial regression rate
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Super adiabatic combustion of H2/Air and H2/N2O mixtures Combust. Flame (IF 4.4) Pub Date : 2024-03-14 Jennifer L. Schurr, Atmadeep Bhattacharya, Alexander A. Konnov, Ossi Kaario
While the impact of H chemistry on super adiabatic flame temperature (SAFT) for hydrocarbons is well understood, super adiabaticity for premixed H combustion has not been previously reported. In the present work, for the first time, premixed H/air and H/NO combustion in 0D and 1D context have been analysed to show that the instantaneous (0D) or local (1D) temperature exceeds the equilibrium temperature
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A detailed kinetic submechanism for OH[formula omitted] chemiluminescence in hydrogen combustion revisited. Part 1 Combust. Flame (IF 4.4) Pub Date : 2024-03-13 Alexander S. Sharipov, Boris I. Loukhovitski, Alexey V. Pelevkin, Mayya R. Korshunova
In this series of two papers, we present a novel physically sound kinetic submechanism aimed at modeling the formation and decay of chemiluminescent (electronically excited) OH molecules in the ignition and combustion of hydrogen and hydrogen-based mixtures over a wide range of thermodynamic parameters and mixture compositions. The present part of this series describes the preparatory stages of the
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Assessing the ignition and combustion of a kerosene droplet containing boron nanoparticles coated with polydopamine and polyvinylidene fluoride Combust. Flame (IF 4.4) Pub Date : 2024-03-12 Zhimin Fan, Zirui Qin, Tianze Deng, Jiyu Guo, Minxuan Li, Xiaoxi Yang, Bo Yin, Larry K.B. Li, Wen Ao
In this study, how the coating of polydopamine (PDA) and polyvinylidene fluoride (PVDF) on boron particles affects the ignition and combustion characteristics of kerosene droplets was investigated. In this work, PVDF was first coated onto boron nanoparticles using PDA as a binder to form double-coated composite particles (denoted as B@PF), and then the B@PF particles were blended into kerosene to produce
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Measurement of laminar burning speed at high pressures using plasma affected flame Combust. Flame (IF 4.4) Pub Date : 2024-03-11 James Shaffer, Omid Askari
Measurements of a propagating flame are crucial to the understanding and verification of important flame phenomena. Specifically, laminar, unstretched flame speed is desired to verify complex flame behavior such as turbulence or chemical kinetic models. This data is also necessary as advanced and more efficient combustion devices operate at these high pressures where this data is less reliable from
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Experimental and kinetic study of ammonia oxidation and NOx emissions at elevated pressures Combust. Flame (IF 4.4) Pub Date : 2024-03-11 Haochen Zhan, Shuming Li, Geyuan Yin, Erjiang Hu, Zuohua Huang
To investigate the effects of pressure and equivalence ratio on ammonia oxidation and the emission of NO, experiments were conducted in a flow reactor at atmospheric pressure and 5.0 MPa between 600 and 1250 K, with equivalence ratios ranging from 0.125 to 1.0. In addition, a kinetic model applicable to ammonia oxidation under high-pressure conditions was developed and validated against the performance
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Comparative radiative property measurements of single biomass and coal particles burning at high reactor temperatures Combust. Flame (IF 4.4) Pub Date : 2024-03-08 Yuan Yao, Aidin Panahi, Yiannis A. Levendis
This research measured the emissivity, temperature and soot loading of pulverized bituminous coal and three types of renewable biomass. Combustion occurred in a laboratory-scale drop tube furnace (DTF), where the fuels experienced high heating rates and ignited and burned in two distinct phases: devolatilization accompanied by volatile matter combustion in envelope flames, and sequential combustion
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The effect of finite molecular volume on the propagation of unsteady spherical flame front Combust. Flame (IF 4.4) Pub Date : 2024-03-07 Zifeng Weng, Yakun Zhang, Brian McN. Maxwell, Rémy Mével
An asymptotic analysis on the dynamics of adiabatic and nonadiabatic spherically expanding laminar flame was performed for real gas described by the Noble-Abel equation of state. The effect of the finite molecular volume was considered and characterized by a covolume parameter. It was demonstrated that the non-ideal model leads to higher flame speed at quasi-steady state and to lower Markstein number
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Numerical study on the shock wave and vortex and their coupling effect on the behavior of the flame induced by the spontaneous ignition of high-pressure hydrogen release Combust. Flame (IF 4.4) Pub Date : 2024-03-05 Liang Gong, Xianwen Zheng, Yifei Han, Tianyu Mo, Xufeng Yang, Yuchun Zhang
High-pressure hydrogen storage is currently the mainstream way of hydrogen storage. However, the risk of spontaneous ignition and subsequent jet flame are serious obstacles to the wide application of hydrogen energy. To further reveal the interaction of shock waves, vortices and flame induced by the spontaneous ignition of high-pressure hydrogen release under the effect of release process and burst
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Plasma-assisted ignition-stabilized combustion (PAISC): Benefits, limitations, and costs Combust. Flame (IF 4.4) Pub Date : 2024-03-04 Ravi Patel, Jeroen van Oijen, Sander Nijdam, Nico Dam
This work aims to find the benefits, limitations, and costs (in terms of plasma energy and NO emissions) of plasma-assisted ignition-stabilized combustion (PAISC). The experiments are performed on a custom-made methane-air jet flame burner with two coaxial flow inlets. Dielectric barrier discharge (DBD) configuration is set up in the outer flow channel which acts as four ignition sources. The DBDs
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Modeling of high-speed, methane-air, turbulent combustion, Part II: Reduced methane oxidation chemistry Combust. Flame (IF 4.4) Pub Date : 2024-03-04 Rui Xu, Sai Sandeep Dammati, Xian Shi, Ethan Samuel Genter, Zoltan Jozefik, Matthew E. Harvazinski, Tianfeng Lu, Alexei Y. Poludnenko, Venkateswaran Sankaran, Alan R. Kerstein, Hai Wang
A reduced, 12-species reaction model (FFCMy-12) is proposed for modeling high-speed turbulent methane flames at high Karlovitz numbers. The model was derived from an early development version (FFCMy) of the 119-species Foundational Fuel Chemistry Model Version 2.0. The reduction was carried out by combining direct species pruning, quasi-steady-state assumption, and reaction lumping, targeting a minimum
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Structural evolution of solid-fuel combustion using laser-induced breakdown spectroscopy and Raman spectroscopy Combust. Flame (IF 4.4) Pub Date : 2024-03-03 Wenkun Zhu, Mengfan Yuan, Christian Axt, Xiaohui Li, Anna Maßmeyer, Rui Sun
One of the major challenges regarding measuring chemical structures with laser-induced breakdown spectroscopy (LIBS) is that, it is difficult to track the source of organic components from atomic spectra since these structures have a similar elemental composition. However, LIBS molecular emissions (C, CN, etc.) provide a possibility to investigate these similar compositions. In the present study, an
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Impact of heat transfer due to fiber conduction, radiation and convection on the interpretation of experiments with isolated droplets Combust. Flame (IF 4.4) Pub Date : 2024-03-02 Mohamad Asrardel, Álvaro Muelas, Taha Poonawala, Javier Ballester
Isolated droplet setups have been extensively used during the last decades to characterize liquid fuel evaporation and combustion, being considered a reference framework approaching the simplest and idealized (canonical) configuration. However, in many cases, this configuration is affected by different experimental artifacts that may lead to non-negligible deviations from the assumed ideal conditions
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Analysis of weak secondary waves in a rotating detonation engine using large-eddy simulation and wavenumber-domain filtering Combust. Flame (IF 4.4) Pub Date : 2024-03-02 Guillaume Vignat, Davy Brouzet, Matthew Bonanni, Matthias Ihme
Rotating detonation engines (RDEs) are pressure-gain combustion devices which allow for a compact and mechanically simple engine design with improved thermodynamic efficiency compared to traditional deflagration devices. However, achieving these gains in practical devices that are operated with non-premixed reactants requires overcoming non-idealities in the mixing and combustion process. We investigate
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Forced ignition modeling of methane-ethylene mixtures in scramjet combustors Combust. Flame (IF 4.4) Pub Date : 2024-03-01 Shinichiro Ogawa, Kan Kobayashi, Sadatake Tomioka
To propose a design guideline for a scramjet combustor at low cost, an ignition model for a scramjet combustor is required. Therefore, the overall aim of this study was to propose an ignition model that could be used to estimate the forced ignition limits within a cavity. In this study, we developed two forced ignition models (FIMs): the forced ignition model in the recirculating zone (FIMR) and the
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Modeling of high-speed, methane–air, turbulent combustion, Part I: One-dimensional turbulence modeling with comparison to DNS Combust. Flame (IF 4.4) Pub Date : 2024-03-01 Zoltan Jozefik, Matthew E. Harvazinski, Venkateswaran Sankaran, Sai Sandeep Dammati, Alexei Y. Poludnenko, Tianfeng Lu, Alan R. Kerstein, Rui Xu, Hai Wang
The ability of the one-dimensional turbulence (ODT) model to serve as a surrogate direct numerical simulation (DNS) is assessed for highly turbulent flames. The ODT model is applied to freely propagating premixed methane–air flames at Karlovitz numbers 10, 10, 10, and 10, and results are compared with DNS. The ODT model solves the conservation equations for momentum, energy, and species on a one-dimensional
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Impact of flash boiling spray on soot generation of a rich fuel–air mixture under various ambient pressures Combust. Flame (IF 4.4) Pub Date : 2024-02-29 Mingli Cui, Weixuan Zhang, Jinhong Fu, Xulin Luo, David L.S. Hung, Min Xu, Xuesong Li
Particulate emission is one of the critical challenges for the modern gasoine direct injection (GDI) engines. Especially under cold start conditions, the global equivalence ratio inside the cylinder is often set quite rich, leading to the generation of a large amount of soot. The fuel distribution state, such as homogeneous mixing and heterogeneous mixing with local rich pockets prior to the combustion
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A machine learning method to predict rate constants for various reactions in combustion kinetic models Combust. Flame (IF 4.4) Pub Date : 2024-02-28 Ning Li, Sanket Girhe, Mingzhi Zhang, Bingjie Chen, Yingjia Zhang, Shenghua Liu, Heinz Pitsch
Accurate prediction of temperature-dependent reaction rate constants is essential for the development of combustion kinetic models. However, the computational expense associated with calculating rate constants using high-level quantum chemistry methods becomes infeasible as the complexity of the kinetic models grows, and alternative approaches relying on analogies can exhibit significant inaccuracies
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Ignition characteristics of single coal particles under ammonia co-firing conditions Combust. Flame (IF 4.4) Pub Date : 2024-02-27 Chenlin Chen, Zhihua Wang, Yong He, Wubin Weng, Kefa Cen
To meet the goal of an international carbon-neutral framework, the promotion of clean coal utilization occupies a vital position in reducing greenhouse gas emissions. Ammonia co-firing is considered as a potential strategy for future power generation to reduce fossil energy consumptions, soot, CO emissions, and hydrocarbon pollutants. In the present work, the ignition characteristics of single coal
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Effect of AP coating or blending on the ignition and combustion of Al particles under a high-pressure water vapour–Ar environment Combust. Flame (IF 4.4) Pub Date : 2024-02-27 Peihui Xu, Xingang Dong, Wenke Zhang, Yuxin Yang, Xueqin Liao, Jianzhong Liu
Overcoming the difficulty of ignition and combustion of aluminium in water vapour is the key to being applied in underwater propellant applications. The effect of coating or blending 20 mass% ammonium perchlorate (namely, AP@Al or AP–Al samples) on the ignition and combustion of Al particles in a 1.0 MPa water vapour–Ar environment was investigated using a constant temperature pressurized combustion
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The effect of the unsaturation degree on the gas-phase autoignition of methyl oleate and methyl linoleate: Experimental and modeling study Combust. Flame (IF 4.4) Pub Date : 2024-02-27 Wei Zhou, Zimu Wang, Yueying Liang, Xiaoqin Zhang, Liang Yu, Xingcai Lu
As the product of transesterification between various oils and alcohols, biodiesel exhibits characteristics of renewability and a wide range of raw materials. The ignition delay times (IDTs) of methyl oleate (MEOLE) and methyl linoleate (MLINO), the primary constituents of biodiesels, were measured in a heated rapid compression machine (RCM) to investigate the impact of CC double bond on the reactivity
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New discovery of aluminium agglomeration in composite solid propellants based on microscopic heating system Combust. Flame (IF 4.4) Pub Date : 2024-02-23 Shipo Li, Zhan Wen, Lu Liu, Xiang Lv, Peijin Liu, Bo Yin, Larry K.B. Li, Wen Ao
The amount of energy delivered to a solid-fueled rocket motor is its most crucial performance indicator. Metallic fuels, such as aluminum, is commonly added to propellants for obtaining high energy densities. In this study, the agglomeration of four distinct types of composite solid propellants, comprising different adhesives, oxidants, and Al particles, during gradual heating was experimentally investigated
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Air humidity influence on combustion of R-1234yf (CF3CFCH2), R-1234ze(E) (trans-CF3CHCHF) and R-134a (CH2FCF3) refrigerants Combust. Flame (IF 4.4) Pub Date : 2024-02-23 Valeri I. Babushok, Gregory T. Linteris
The influence of air humidity on flame propagation in mixtures of hydrofluorocarbons (HFCs) with air was studied through numerical simulations and comparison with measurements from the literature. Water vapor added to the air in mixtures of fluorine rich hydrofluorocarbons (F/H ≥ 1) can be considered as a fuel additive that increases the production of radicals (H, O, OH) and increases the overall reaction
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Experimental and modeling study of NO2 addition effects on autoignition behavior of propylene Combust. Flame (IF 4.4) Pub Date : 2024-02-21 Fuquan Deng, Xinbo Huang, Song Cheng, Yingjia Zhang, Zuohua Huang, Hui Tang, Hongtao Zheng, Xiao Liu
Autoignition behaviors of NO/CH/O/Ar mixtures with the blending ratio of [NO]/[CH] ranging from 0 % to 100 % were measured at pressure of 2.03E+5 - 1.01E+6 Pa, temperature of 950 – 1820 K, and equivalence ratio of 0.5 – 2.0 in a high-pressure shock tube. NO blending effects are characterized through changes in ignition delay times. Experiments indicate the strong promoting effect of NO on the reactivity