scholarly journals Quasi-steady stages in the process of premixed flame acceleration in narrow channels

2013 ◽  
Vol 25 (9) ◽  
pp. 096101 ◽  
Author(s):  
D. M. Valiev ◽  
V. Bychkov ◽  
V. Akkerman ◽  
L.-E. Eriksson ◽  
C. K. Law
Keyword(s):  
Premixed Flame ◽  
Narrow Channels ◽  
Flame Acceleration

scholarly journals Premixed-flame oscillations in narrow channels

2019 ◽  
Vol 4 (10) ◽  
Author(s):  
Daniel Martínez-Ruiz ◽  
Fernando Veiga-López ◽  
Mario Sánchez-Sanz
Keyword(s):  
Premixed Flame ◽  
Narrow Channels

scholarly journals Video: Premixed-flame oscillations in narrow channels

2018 ◽  
Author(s):  
Daniel Martínez-Ruiz ◽  
Fernando Veiga-López ◽  
Mario Sánchez Sanz
Keyword(s):  
Premixed Flame ◽  
Narrow Channels

Flame acceleration and deflagration-to-detonation transition in narrow channels with thin obstacles

2018 ◽  
Vol 32 (29) ◽  
pp. 1850354 ◽  
Author(s):  
Jin Huang ◽  
Xiangyu Gao ◽  
Cheng Wang
Keyword(s):  
Turbulent Flame ◽  
Narrow Channels ◽  
Flame Acceleration ◽  
Deflagration To Detonation Transition ◽  
Smooth Channel ◽  
Detonation Transition ◽  
Run Up ◽  
Thin Obstacle ◽  
Strong Confinement ◽  
Small Spacing

The entire process of deflagration-to-detonation transition (DDT) in narrow channels with thin obstacle configurations is studied through high-resolution simulations. The results show that the confinement and disturbance of obstacles promote considerably the flame acceleration and DDT. There exist two modes of DDT associating with obstacle spacing S. For small spacing S, the flame acceleration depends on strong confinement and jet flow between obstacles; eventually DDT occurs due to early burning amplified by shocks in front of the flame. However, for large spacing S, the flame acceleration is mainly attributed to turbulence; DDT results from the interaction of reflection shock with turbulent flame. It is found that the run-up distance of DDT in the obstructed channels shortens significantly, as compared with that in the smooth channel.

Impacts of the Lewis and Markstein numbers on premixed flame acceleration in channels due to wall friction

2022 ◽  
Vol 34 (1) ◽  
pp. 013604
Author(s):  
Serdar Bilgili ◽  
Vitaly Bychkov ◽  
V'yacheslav Akkerman
Keyword(s):  
Premixed Flame ◽  
Wall Friction ◽  
Flame Acceleration

Experimental Study On Premixed Flame Acceleration In Closed Pipe

2013 ◽  
Vol 62 (1) ◽  
Author(s):  
M. H. Mat Kiah ◽  
R. M. Kasmani
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Equivalence Ratio ◽  
Flame Speed ◽  
The Other ◽  
Premixed Flame ◽  
High Mass ◽  
Mass Burning Rate ◽  
Straight Pipe ◽  
Flame Acceleration

An experimental study has been carried out to investigate the flame acceleration in closed pipe. A horizontal steel pipe, with 2 m long and 0.1 m diameter, giving L/D ratio of 20 was used in this project. For test with 90 degree bends, the bend has a radius of 0.1 m and added a further 1 m to the length of the pipe (based on the centerline length of the segment). Ignition was affected at one end of the vessel while the other end was closed. Natural gas/oxygen mixtures were studied with equivalence ratio, Ф ranges from 0.5 to 1.8. It was demonstrated that bending pipe gave three times higher in overpressure (5.5 bars) compared to 2.0 bars of straight pipe. It is also shown that the flame speed is 63 m s-1, greater by factor of ~ 3 for explosion in bending pipe in comparison with straight pipe (23 m s-1). This is due to bending acting similar to obstacles. This mechanism could induce and create more turbulence, initiating the combustion of unburned pocket at the corner region, causing high mass burning rate and hence, increasing the flame speed.

scholarly journals Acceleration of Premixed Flames in Obstructed Pipes with Both Extremes Open

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4094
Author(s):  
Abdulafeez Adebiyi ◽  
Olatunde Abidakun ◽  
V’yacheslav Akkerman
Keyword(s):  
Flame Propagation ◽  
Premixed Flame ◽  
Critical Parameters ◽  
Reacting Flow ◽  
Computational Simulations ◽  
Chemical Parameters ◽  
Flow Equations ◽  
Flame Acceleration ◽  
Logistic Regression Algorithm ◽  
Steady Propagation

Premixed flame propagation in obstructed channels with both extremes open is studied by means of computational simulations of the reacting flow equations with a fully-compressible hydrodynamics, transport properties (heat conduction, diffusion and viscosity) and an Arrhenius chemical kinetics. The aim of this paper is to distinguish and scrutinize various regimes of flame propagation in this configuration depending on the geometrical and thermal-chemical parameters. The parametric study includes various channel widths, blockage ratios, and thermal expansion ratios. It is found that the interplay of these three critical parameters determines a regime of flame propagation. Specifically, either a flame propagates quasi-steady, without acceleration, or it experiences three consecutive distinctive phases (quasi-steady propagation, acceleration and saturation). This study is mainly focused on the flame acceleration regime. The accelerating phase is exponential in nature, which correlates well with the theoretical prediction from the literature. The accelerating trend also qualitatively resembles that from semi-open channels, but acceleration is substantially weaker when both extremes are open. Likewise, the identified regime of quasi-steady propagation fits the regime of flame oscillations, found for the low Reynolds number flames. In addition, the machine learning logistic regression algorithm is employed to characterize and differentiate the parametric domains of accelerating and non-accelerating flames.

scholarly journals Computational Study of Premixed Flame Propagation in Micro-Channels with Nonslip Walls: Effect of Wall Temperature

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 36
Author(s):  
Orlando J. Ugarte ◽  
V’yacheslav Akkerman
Keyword(s):  
Flame Propagation ◽  
Computational Study ◽  
Reacting Flow ◽  
Narrow Channels ◽  
Flow Equations ◽  
Flame Acceleration ◽  
Flame Dynamics ◽  
Micro Channels ◽  
Fuel Mixtures ◽  
The Impact

This investigation evaluates the propagation of premixed flames in narrow channels with isothermal walls. The study is based on the numerical solution of the set of fully-compressible, reacting flow equations that includes viscosity, diffusion, thermal conduction and Arrhenius chemical kinetics. Specifically, channels and pipes with one extreme open and one extreme closed are considered such that a flame is sparked at the closed extreme and propagates towards the open one. The isothermal channel walls are kept at multiple constant temperatures in the range from Tw=300 K to 1200 K. The impact of these isothermal walls on the flame dynamics is studied for multiple radii of the channel (R) and for various thermal expansion ratios (Θ), which approximate the thermal behavior of different fuel mixtures in the system. The flame dynamics in isothermal channels is also compared to that with adiabatic walls, which were previously found to produce exponential flame acceleration at the initial stage of the burning process. The results show that the heat losses at the walls prevent strong acceleration and lead to much slower flame propagation in isothermal channels as compared to adiabatic ones. Four distinctive regimes of premixed burning in isothermal channels have been identified in the Θ−Tw−R space: (i) flame extinction; (ii) linear flame acceleration; (iii) steady or near-steady flame propagation; and (iv) flame oscillations. The physical processes in each of these regimes are discussed, and the corresponding regime diagrams are presented.

scholarly journals Influence of Transverse Slot Jet on Premixed Flame Acceleration

2020 ◽  
Vol 36 (1) ◽  
pp. 59-67
Author(s):  
Dylan J. Tarrant ◽  
Jessica M. Chambers ◽  
Peter H. Joo ◽  
Kareem Ahmed
Keyword(s):  
Premixed Flame ◽  
Flame Acceleration ◽  
Transverse Slot
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