Article
Chemistry, Physical
Yi Wu, Xiaoping Wen, Zhidong Guo, Sen Zhang, Haoxin Deng, Fahui Wang
Summary: This study focuses on the explosion characteristics of premixed gas with different volume fractions of hydrogen in a narrow channel. The results show that the hydrogen volume fraction and ignition position significantly affect the flame structure, flame front speed, and explosion overpressure.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Chemistry, Physical
Yi Qin, Xiaowei Chen
Summary: This paper conducts a numerical study of flame propagation during hydrogen explosion in a closed duct with obstacles, showing that the flame speed is proportional to the number of obstacles, and the flame undergoes different stages of evolution during the explosion process.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Thermodynamics
J. Melguizo-Gavilanes, Y. Ballossier, L. M. Faria
Summary: A combined experimental and theoretical study on the deflagration-to-detonation transition (DDT) in smooth narrow channels has been presented, showing that some of the features of late stage DDT can be qualitatively captured by a simple one-dimensional scalar equation. Inspection of the structure and stability of the traveling wave solutions in the model, and comparison with experimental observations, suggest a possible mechanism responsible for front acceleration and transition to detonation.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Energy & Fuels
Yu Liu, Dawei Rao, Enqing Wang, Hongan Ma, Weilin Zheng, Wen Zeng
Summary: This study carried out experiments to investigate the unstable flame propagation processes of RP-3/air premixed flame. The results showed that the flame tended to be unstable with increased equivalence ratio and initial pressure. The study also revealed the effects of diffusional-thermal and hydrodynamic instability on the acceleration exponent alpha of the flame.
Article
Thermodynamics
Faizan H. Vance, Arne Scholtissek, Philip de Goey, Jeroen van Oijen, Christian Hasse
Summary: Combustion of hydrogen can reduce carbon-based emissions, but it presents challenges due to the high flame speed and Lewis number effects. Traditional burners cannot provide the same operational range for hydrogen flames as for hydrocarbon flames. Therefore, it is important to study the unique stabilization behavior of hydrogen flames and explore non-conventional burner concepts.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Yedhu Krishna, Ariff M. Mahuthannan, Xinguang Luo, Deanna A. Lacoste, Gaetano Magnotti
Summary: This study demonstrates high-speed filtered Rayleigh scattering for time-resolved temperature measurements in premixed flames propagating in small channels. The instrument relies on a pulse burst laser and a CCD camera in specific modes to achieve high signal to noise ratio. Results show high precision and reliability of the system for temperature measurements.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
V Bykov, A. Koksharov, M. Kuznetsov, V. P. Zhukov
Summary: The problem of sudden flame acceleration and Deflagration to Detonation Transition (DDT) in narrow channels is reconsidered in this study. Both experimental and numerical approaches are used to investigate a hydrogen-oxygen combustion system. The results show that the flame acceleration is highly sensitive to the mixture composition. The proposed model successfully reproduces the main features of the phenomenon and suggests a simple criterion for the onset of flame self-acceleration.
COMBUSTION AND FLAME
(2022)
Article
Mechanics
Y. Ballossier, F. Virot, J. Melguizo-Gavilanes
Summary: Flame propagation experiments were conducted in stoichiometric H-2-air, and the dynamics of flame acceleration in a channel were observed. It was found that boundary conditions near the ignition end had the greatest influence on the front position, with other parameters playing minor roles. A simple acoustic model was used to explain the increased acceleration rates observed in certain cases.
Article
Physics, Fluids & Plasmas
Jorge Yanez Escanciano, Mike Kuznetsov, Fernando Veiga-Lopez
Summary: The physical limits of unconventional flame propagation regimes in combustible gaseous mixtures approaching the lean quenching limit of hydrogen-air flames in narrow gaps have been analyzed. The outbreak of unconventional propagation is mostly due to heat losses and is controlled by the Peclet number, appearing only in thin channels, with the Lewis number not determining the propagation regime. An equation describing the optimal border of the unconventional regime has been derived from experiments.
Article
Energy & Fuels
Yuan Mei, Jian Shuai, Yuntao Li, Ning Zhou, Wei Ren, Fei Ren
Summary: The combustion characteristics of hydrogen under different shape obstacles are investigated, focusing on flame structure, propagation velocity and explosion overpressure. Results show that passing through grid-type obstacles with many voids makes it difficult for the flame front to recover to the regular front. The grid-type obstacle can improve the sensitivity to the blocking rate by reducing the void area and leads to a severe distortion of the flame front.
Article
Mechanics
Peng Du, Rui Xue, Zhao Yang, Bing Liu, Shaohua Zhu
Summary: Shock wave focusing is a new type of initiation method without external ignition devices. Numerical simulations were used to investigate the detailed flow field evolution of the focusing process with kerosene as fuel. Two detonation initiation modes were found, namely direct initiation mode and reflected shock wave collision initiation mode.
Article
Thermodynamics
Sang Min Lee, Hye Jin Jang, Nam Il. Kim
Summary: The effects of length-scale and oxidant composition on the propagation characteristics of premixed propane flames were investigated. It was found that increasing the concentration of N2 in the oxidant led to a decrease in flame propagation velocity and weaker flame oscillation. The mechanism of flame oscillation was refined by considering the Lewis number and the variation in momentum across the flame.
COMBUSTION AND FLAME
(2023)
Article
Mechanics
Claude M. Dion, Damir M. Valiev, V'yacheslav Akkerman, Berk Demirgok, Orlando J. Ugarte, Lars-Erik Eriksson, Vitaly Bychkov
Summary: This study investigates the propagation of a premixed flame in micro-channels with smooth non-slip isothermal walls, focusing on the dynamics of flame extinction. Numerical simulations show that initial flame acceleration occurs after ignition at the closed end, but at a slower rate and for a shorter duration compared to the adiabatic case. Heat loss to the walls leads to changes in the flame front shape and eventual flame extinction.
Article
Mechanics
Olatunde Abidakun, Abdulafeez Adebiyi, Damir Valiev, V'yacheslav Akkerman
Summary: This study investigates non-equidiffusive combustion in micro-channels, finding that flames oscillate at low Lewis numbers in adiabatic channels, while flames with Le > 1 show a tendency towards steady propagation. The impact of heat losses in isothermal channels may dominate over the role of the Lewis number, with qualitative differences in burning behavior compared to adiabatic channels.
Article
Thermodynamics
Vadim N. Kurdyumov, Carmen Jimenez
Summary: This study investigates the structure and dynamics of premixed flames in narrow channels with a highly conductive wall segment. The findings reveal the existence of multiple steady-state regimes, with several steady solutions being simultaneously stable. The stability analysis is confirmed by time-dependent simulations, which also demonstrate the possibility of nonlinear periodic and chaotic dynamics under certain conditions.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Abdulafeez Adebiyi, Elizabeth Ridgeway, Rawan Alkandari, Amanda Cathreno, Damir Valiev, V'yacheslav Akkerman
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2019)
Article
Nanoscience & Nanotechnology
Abdulafeez Adebiyi, Rawan Alkandari, Damir Valiev, V'yacheslav Akkerman
Article
Physics, Fluids & Plasmas
Abdulafeez Adebiyi, Olatunde Abidakun, Gbolahan Idowu, Damir Valiev, V'yacheslav Akkerman
PHYSICAL REVIEW FLUIDS
(2019)
Article
Mechanics
Mohammed Alkhabbaz, Olatunde Abidakun, Damir Valiev, V'yacheslav Akkerman
Article
Mechanics
Olatunde Abidakun, Abdulafeez Adebiyi, Damir Valiev, V'yacheslav Akkerman
Summary: This study investigates non-equidiffusive combustion in micro-channels, finding that flames oscillate at low Lewis numbers in adiabatic channels, while flames with Le > 1 show a tendency towards steady propagation. The impact of heat losses in isothermal channels may dominate over the role of the Lewis number, with qualitative differences in burning behavior compared to adiabatic channels.
Article
Physics, Fluids & Plasmas
Shuyu Ding, Kai Huang, Yifan Han, Damir Valiev
Summary: This study investigates laminar boundary layer flashback in channels with wall roughness using two-dimensional simulations. The results show that wall roughness can attenuate flashback tendency by enhancing heat loss to the boundary. Furthermore, heat loss enhancement due to wall roughness may play a dominant role in determining flame propagation characteristics.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Thermodynamics
Ruixue Feng, Andrea Gruber, Jacqueline H. Chen, Damir M. Valiev
Summary: This study investigates the interaction between periodic shear flow and laminar premixed flame through numerical simulation, revealing that the increase in the amplitude of periodic shear flow and gas expansion ratio leads to an increase in curved flame velocity, while the effect of periodic shear wavelength on flame velocity is non-monotonic.
COMBUSTION AND FLAME
(2021)
Article
Mechanics
Claude M. Dion, Damir M. Valiev, V'yacheslav Akkerman, Berk Demirgok, Orlando J. Ugarte, Lars-Erik Eriksson, Vitaly Bychkov
Summary: This study investigates the propagation of a premixed flame in micro-channels with smooth non-slip isothermal walls, focusing on the dynamics of flame extinction. Numerical simulations show that initial flame acceleration occurs after ignition at the closed end, but at a slower rate and for a shorter duration compared to the adiabatic case. Heat loss to the walls leads to changes in the flame front shape and eventual flame extinction.
Article
Optics
Emil Thorin, Kun Zhang, Damir Valiev, Florian M. Schmidt
Summary: The study conducted simultaneous, high-dynamic range measurements of gaseous potassium species released from biomass during thermochemical conversion using photofragmentation tunable diode laser absorption spectroscopy. The experimental results showed good agreement with simulations under specific conditions, but potassium hydroxide was over-predicted in simulations of fuel-rich flames.
Article
Mechanics
Yifan Han, Mikhail Modestov, Damir M. Valiev
Summary: The study investigated the hydrodynamic instability of a laminar premixed flame propagating in a Hele-Shaw cell, revealing that wall heat losses weaken flame instability while momentum losses enhance it. The width of the Hele-Shaw cell and the heat loss coefficient have varying effects on the instability growth rate, with a potential non-monotonic dependence demonstrated.
Article
Physics, Fluids & Plasmas
Mohammed AlKhabbaz, Furkan Kodakoglu, Damir Valiev, V'yacheslav Akkerman
Summary: This study investigates the effects of mechanistic (shear stress) and thermal wall conditions on the finger-shaped flame acceleration scenario in the early stages of burning in channels. The results show that the difference between slip and nonslip walls is small before the flame contacts the sidewall. The wall temperature has an impact on flame acceleration, with flames accelerating faster in hotter channels. Additionally, an octopuslike flame front is observed in channels with preheated isothermal walls. Thermal expansion significantly affects the flame acceleration rate, and variations in channel width also influence flame propagation.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Thermodynamics
Ruixue Feng, Damir Valiev
Summary: The influence of gas expansion on the velocity of freely propagating curved stationary premixed flames is studied, with a focus on the nonlinear effects of the Darrieus-Landau instability. The results show that the curved flame velocity increases with gas expansion coefficient, and a critical channel width is identified where the flame velocity starts to grow rapidly.
COMBUSTION SCIENCE AND TECHNOLOGY
(2022)
Article
Energy & Fuels
Kai Huang, Damir M. Valiev, Hongtao Zhong, Wenhu Han
Summary: In recent years, boundary layer flame flashback (BLF) has become more significant due to the widespread use of alternative fuels to promote carbon neutrality. The theoretical modeling of BLF still relies on the critical gradient model (CGM) proposed in the 1940s. This study focuses on the effects of thermal gas expansion and confinement on the flame-flow interaction in laminar BLF. The simulations show that the assumption of flame having no influence on the upstream flow, employed in the CGM, is not fulfilled under confinement for a realistic thermal gas expansion.
Article
Physics, Fluids & Plasmas
Olatunde Abidakun, Abdulafeez Adebiyi, Damir Valiev, V'yacheslav Akkerman
Summary: Equidiffusive premixed combustion in obstructed channels with both open, non-reflecting ends exhibits different forms of flame propagation. The study investigates how these modes of combustion are altered under non-equidiffusive conditions characterized by a non-unity Lewis number. It is found that the flame dynamics and morphology are influenced by the value of Le, as well as other geometric parameters of the channel, leading to variations in burning velocities, oscillation amplitude, and frequency.
Article
Physics, Fluids & Plasmas
Furkan Kodakoglu, Sinan Demir, Damir Valiev, V'yacheslav Akkerman