Effect of folds and pockets on the topology and propagation of premixed turbulent flames

Fogla, Navin; Creta, Francesco; Matalon, Moshe

doi:10.1016/j.combustflame.2015.04.012

Cited by 61 publications

(38 citation statements)

References 88 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Accurate and robust modelling of these devices therefore requires a detailed understanding of such interactions. Studies have shown that flame-flame interactions can cause changes in flame surface area [1,2], local and global consumption speeds [3], and flame topology [4,5]. Interaction between adjacent flames can affect the shape [6,7], static stability, [8] and dynamic stability [9][10][11][12][13] of a turbulent flame.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The role of flow interaction in flame–flame interaction events in a dual burner experiment

Tyagi

Boxx

Peluso

et al. 2019

Proceedings of the Combustion Institute

View full text Add to dashboard Cite

A dual burner experiment is used to investigate how flow interactions affect local flame-flame interaction in turbulent premixed flames. The presence of adjacent flows influences the local structure of these flames and understanding the sensitivity of these flames to adjacent flows is essential for multinozzle combustion devices. To study this sensitivity, a high-aspect-ratio Bunsen flame operating at a constant flow velocity is placed adjacent to an identical burner with non-reacting flow at varying velocities. High-speed OH-planar laser induced fluorescence and stereoscopic-particle image velocimetry measurements are performed to capture flame-front locations and velocity fields. A non-rigid image registration technique is used to calculate the local flame-area variations that occur due to topological differences, and conditional statistics are extracted to relate the local behavior to changes observed in the global behavior of the flames. Extracted flame curvatures and time-averaged progress variables conditioned on flame-flame interactions show differences existing in the inner and outer flame branches near the flame-attachment region. Statistics of these results are presented and compared for all test cases.

show abstract

Section: Introductionmentioning

confidence: 99%

“…A. Tyagi1 , I. Boxx 2 , S. Peluso 1 , J. O'Connor 1 * 1 Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA,…”

mentioning

confidence: 99%

The role of flow interaction in flame–flame interaction events in a dual burner experiment

Tyagi

Boxx

Peluso

et al. 2019

Proceedings of the Combustion Institute

View full text Add to dashboard Cite

show abstract

“…1 from [45] does not indicate a substantial effect of σ on the mean (time-averaged) in the flamelet regime of premixed turbulent combustion. Recent unsteady 2D simulations of hydrodynamically unstable (“supercritical”) flames [46, 47] indicate a weak dependence of S t on σ in spite of substantial influence of the DL instability on the simulated flames. …”

Section: Introductionmentioning

confidence: 99%

Does Density Ratio Significantly Affect Turbulent Flame Speed?

Lipatnikov

Jiang

et al. 2017

Flow Turbulence Combust

View full text Add to dashboard Cite

In order to experimentally study whether or not the density ratio σ substantially affects flame displacement speed at low and moderate turbulent intensities, two stoichiometric methane/oxygen/nitrogen mixtures characterized by the same laminar flame speed S L = 0.36 m/s, but substantially different σ were designed using (i) preheating from T u = 298 to 423 K in order to increase S L, but to decrease σ, and (ii) dilution with nitrogen in order to further decrease σ and to reduce S L back to the initial value. As a result, the density ratio was reduced from 7.52 to 4.95. In both reference and preheated/diluted cases, direct images of statistically spherical laminar and turbulent flames that expanded after spark ignition in the center of a large 3D cruciform burner were recorded and processed in order to evaluate the mean flame radius and flame displacement speed with respect to unburned gas. The use of two counter-rotating fans and perforated plates for near-isotropic turbulence generation allowed us to vary the rms turbulent velocity by changing the fan frequency. In this study, was varied from 0.14 to 1.39 m/s. For each set of initial conditions (two different mixture compositions, two different temperatures T u, and six different , five (respectively, three) statistically equivalent runs were performed in turbulent (respectively, laminar) environment. The obtained experimental data do not show any significant effect of the density ratio on S t. Moreover, the flame displacement speeds measured at u′/S L = 0.4 are close to the laminar flame speeds in all investigated cases. These results imply, in particular, a minor effect of the density ratio on flame displacement speed in spark ignition engines and support simulations of the engine combustion using models that (i) do not allow for effects of the density ratio on S t and (ii) have been validated against experimental data obtained under the room conditions, i.e. at higher σ.

show abstract

“…Therefore, a more accurate modelling of the phenomena at play requires bridge building the knowledge of the internal structure of flames, gathered generally in laminar situations, to turbulent configurations. A very elegant example of such an achievement was recently provided by Fogla, Creta & Matalon (2015, 2017.…”

Section: Introductionmentioning

confidence: 99%

Isolating strain and curvature effects in premixed flame/vortex interactions

et al. 2017

View full text Add to dashboard Cite

This study focuses on the response of premixed flames to a transient hydrodynamic perturbation in an intermediate situation between laminar stretched flames and turbulent flames: an axisymmetric vortex interacting with a flame. The reasons motivating this choice are discussed in the framework of turbulent combustion models and flame response to the stretch rate. We experimentally quantify the dependence of the flame kinematic properties (displacement and consumption speeds) to geometrical scalars (stretch rate and curvature) in flames characterized by different effective Lewis numbers. Whilst the displacement speed can be readily measured using particle image velocimetry and tomographic diagnostics, providing a reliable estimate of the consumption speed from experiments remains particularly challenging. In the present work, a method based on a budget of fuel on a well chosen domain is proposed and validated both experimentally and numerically using two-dimensional direct numerical simulations of flame/vortex interactions. It is demonstrated that the Lewis number impact neither the geometrical nor the kinematic features of the flames, these quantities being much more influenced by the vortex intensity. While interacting with the vortex, the flame displacement (at an isotherm close to the leading edge) and consumption speeds are found to increase almost independently of the type of fuel. We show that the total stretch rate is not the only scalar quantity impacting the flame displacement and consumption speeds and that curvature has a significant influence. Experimental data are interpreted in the light of asymptotic theories revealing the existence of two distinct Markstein numbers, one characterizing the dependence of flame speed to curvature, the other to the total stretch rate. This theory appears to be well suited for representing the evolution of the displacement speed with respect to either the total stretch rate, curvature or strain rate. It also explains the limited dependence of the flame displacement speed to Lewis number and the strong correlation with curvature observed in the experiments. An explicit relationship between displacement and consumption speeds is also given, indicating that the fuel consumption rate is likely to be altered by both the total stretch rate and curvature.

show abstract

Effect of folds and pockets on the topology and propagation of premixed turbulent flames

Cited by 61 publications

References 88 publications

The role of flow interaction in flame–flame interaction events in a dual burner experiment

The role of flow interaction in flame–flame interaction events in a dual burner experiment

Does Density Ratio Significantly Affect Turbulent Flame Speed?

Isolating strain and curvature effects in premixed flame/vortex interactions

Contact Info

Product

Resources

About