scholarly journals Asymptotic expressions for turbulent burning velocity at the leading edge of a premixed flame brush and their validation by published measurement data

2014 ◽  
Vol 26 (12) ◽  
pp. 125103 ◽  
Author(s):  
Jaeseo Lee ◽  
Gwang G. Lee ◽  
Kang Y. Huh
Keyword(s):  
Burning Velocity ◽  
Measurement Data ◽  
Leading Edge ◽  
Premixed Flame ◽  
Asymptotic Expressions ◽  
Turbulent Burning Velocity ◽  
Flame Brush

scholarly journals 804 Turbulent Burning Velocity of Spherically Propagating Premixed Flame based on Mean Progress Variable

2013 ◽  
Vol 2013.66 (0) ◽  
pp. 241-242
Author(s):  
Akihiro HAYAKAWA ◽  
Toshihiko KUBO ◽  
Taiki TSUKAMOTO ◽  
Yukihide NAGANO ◽  
Toshiaki KITAGAWA
Keyword(s):  
Burning Velocity ◽  
Premixed Flame ◽  
Progress Variable ◽  
Turbulent Burning Velocity

scholarly journals Effects of Mean Inflow Velocity and Droplet Diameter on the Propagation of Turbulent V-Shaped Flames in Droplet-Laden Mixtures

Fluids ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Gulcan Ozel Erol ◽  
Nilanjan Chakraborty
Keyword(s):  
Burning Velocity ◽  
Droplet Diameter ◽  
Gaseous Mixture ◽  
Mean Flow ◽  
Mean Values ◽  
Inflow Velocity ◽  
The Mean ◽  
Turbulent Burning Velocity ◽  
Mean Flow Velocity ◽  
Flame Brush

Three-dimensional carrier phase Direct Numerical Simulations of V-shaped n-heptane spray flames have been performed for different initially mono-sized droplet diameters to investigate the influence of mean flow velocity on the burning rate and flame structure at different axial locations from the flame holder. The fuel is supplied as liquid droplets through the inlet and an overall (i.e., liquid + gaseous) equivalence ratio of unity is retained in the unburned gas. Additionally, turbulent premixed stoichiometric V-shaped n-heptane flames under the same turbulent flow conditions have been simulated to distinguish the differences in combustion behaviour of the pure gaseous phase premixed combustion in comparison to the corresponding behaviour in the presence of liquid n-heptane droplets. It has been found that reacting gaseous mixture burns predominantly under fuel-lean mode and the availability of having fuel-lean mixture increases with increasing mean flow velocity. The extent of flame wrinkling for droplet cases has been found to be greater than the corresponding gaseous premixed flames due to flame-droplet-interaction, which is manifested by dimples on the flame surface, and this trend strengthens with increasing droplet diameter. As the residence time of the droplets within the flame decreases with increasing mean inflow velocity, the droplets can survive for larger axial distances before the completion of their evaporation for the cases with higher mean inflow velocity and this leads to greater extents of flame-droplet interaction and droplet-induced flame wrinkling. Mean inflow velocity, droplet diameter and the axial distance affect the flame brush thickness. The flame brush thickens with increasing droplet diameter for the cases with higher mean inflow velocity due to the predominance of fuel-lean gaseous mixture within the flame. However, an opposite behaviour has been observed for the cases with lower mean inflow velocity where the smaller extent of flame wrinkling due to smaller values of integral length scale to flame thickness ratio arising from higher likelihood of fuel-lean combustion for larger droplets dominates over the thickening of the flame front. It has been found that the major part of the heat release arises due to premixed mode of combustion for all cases but the contribution of non-premixed mode of combustion to the total heat release has been found to increase with increasing mean inflow velocity and droplet diameter. The increase in the mean inflow velocity yields an increase in the mean values of consumption and density-weighted displacement speed for the droplet cases but leads to a decrease in turbulent burning velocity. By contrast, an increase in droplet diameter gives rise to decreases in turbulent burning velocity, and the mean values of consumption and density-weighted displacement speeds. Detailed physical explanations have been provided to explain the observed mean inflow velocity and droplet diameter dependences of the flame propagation behaviour.

scholarly journals Determination of the Burning Velocity Domain of a Statistically Stationary Turbulent Premixed Flame in Presence of Counter-Gradient Transport

2011 ◽  
Vol 2011 ◽  
pp. 1-7
Author(s):  
V. A. Sabel'nikov ◽  
P. Bruel
Keyword(s):  
Burning Velocity ◽  
Leading Edge ◽  
Premixed Flame ◽  
Recent Experimental Data ◽  
Steady Regime ◽  
Number Range ◽  
Turbulent Premixed Flame ◽  
Domain Of Existence ◽  
Turbulent Premixed

The present study aims at providing a complete picture of the various propagation scenarios that a statistically stationary turbulent premixed flame may possibly undergo. By explicitly splitting the scalar turbulent flux between its gradient and counter-gradient contributions, the scalar governing equation is rewritten as an ordinary differential equation in the phase space. Then, an analysis of the characteristic equations in the vicinity of the reactants and products side is carried out. The domain of existence of the propagation velocity is then determined and positioned over the relevant Bray number range. It is shown in particular that when a counter-gradient transport at the cold leading edge of the flame is dominant, there still exists a possibility of observing a steady regime of propagation. This conclusion is compatible with recent experimental data and observations based on the analysis of direct numerical simulations.

Technical Note: The importance of turbulence intensity, eddy size and flame size in spark ignited, premixed flame growth

1997 ◽  
Vol 211 (1) ◽  
pp. 83-86 ◽  
Author(s):  
D S-K Ting ◽  
M. D. Checkel
Keyword(s):  
Turbulence Intensity ◽  
Burning Velocity ◽  
Lewis Number ◽  
Technical Note ◽  
Premixed Flame ◽  
Mean Square ◽  
Laminar Burning Velocity ◽  
The Mean ◽  
Turbulent Burning Velocity ◽  
Velocity Turbulence

The effects of laminar burning velocity, turbulence intensity, flame size and eddy size on the turbulent burning velocity of a premixed growing flame were experimentally separated in a 125 mm cubical chamber with lean methane-air mixtures spark ignited at 1 atm and 300 K. The turbulence was up to 2 m/s with 1 to 4 mm Taylor microscale. For the near unity Lewis number and near zero Markstein number mixture considered here, the turbulent burning velocity, St, can be approximated as: St = Sl + Cd(r/λ)u′, where Sl is the laminar burning velocity, r is the mean flame radius, λ is the Taylor microscale, u′ is the root mean square (r.m.s.) turbulence intensity and Cd is a constant of the order 0.02.

scholarly journals Turbulent burning velocity of ammonia/oxygen/nitrogen premixed flame in O2-enriched air condition

Fuel ◽  
2020 ◽  
Vol 268 ◽  
pp. 117383 ◽  
Author(s):  
Yu Xia ◽  
Genya Hashimoto ◽  
Khalid Hadi ◽  
Nozomu Hashimoto ◽  
Akihiro Hayakawa ◽  
...  
Keyword(s):  
Burning Velocity ◽  
Premixed Flame ◽  
Turbulent Burning Velocity
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