Premixed flames propagating freely in tubes

Abstract

This paper reports an experimental investigation of premixed propane and methane-air flames propagating freely in tubes 1.5 m long and with diameters 54 and 94 mm. Two regimes of propagation are distinguished by correlating the flame speed and the radius of curvature at the flame tip. The characteristic lengths are then related to the cut-off wavelengths estimated from linear theories and compared to previous results of Michelson-Sivashinsky simulations.

Darrieus–Landau instability and Markstein numbers of premixed flames in a Hele-Shaw cell

“…Even without turbulence, the propagation of a laminar flame in a tube can lead to 5 a very complex non-linear evolution (these flames are often called self-turbulent) if the tube is large enough [2]. However it is difficult to study quantitatively the instability in three dimensions.…”

Large scale effects in weakly turbulent premixed flames

“…Recent investigations have revealed a substantial difference in the morphological and propagative properties of large-scale ( L > λ c ) compared to small scale flames. The characteristic flame wrinkling due to DL instability in large-scale flames was observed in both laminar and turbulent settings in multiple experimental [9][10][11][12] and numerical [13][14][15][16][17][18] studies. The DL induced morphology was found to be associated to an increase in flame area and to a consequent increase in laminar as well as turbulent propagation speed.…”

Quantitative Analysis of Flame Instabilities in a Hele-Shaw Burner

“…More specifically, the Sivashinsky equation [5] is known to generate a front dynamics that is qualitatively in agreement with the propagation of unstable premixed flame fronts. This equation in its non dimensional version (see [6] for instance), can be written as: φ t + 1/2(φ x ) 2 = I(φ ) + νφ xx (1) where φ is the flame front position, x the transverse coordinate, I(φ ) is the Landau operator corresponding to multiplication by |k| in Fourier space. The right hand size corresponds to the linear dispersion relation, of the form σ = ak − bk 2 , where σ is the growth rate of perturbations, k the wavenumber.…”

“…This cut-off wavelength is also supposed to be the scaling length that controls the velocity of weakly turbulent flames [3] or of a self-turbulent flame with a fractal structure [7]. This length can be evaluated by direct measurements [6] or from the knowledge of the stability limits of planar premixed flames [8,9], but with a lot of uncertainties.…”

“…Precise experimental studies of the hydrodynamic instability are rare, and even the propagation of a laminar flame in a tube can lead to a very complex non-linear evolution if the tube is large enough [6]. It has been suggested by Joulin and Sivashinsky in [10] and first obtained experimentally by Ronney in [11] (see also [12]), to study flames in a quasi two dimensional configuration in a Hele-Shaw cell.…”