Etude de la combustion de gaz de synthèse issus d'un processus de ...

Experimental and numerical laminar syngas combustion
These schlieren images show generally a spherical pattern. Stoichiometric mixture is
the faster one, followed by the rich mixture (φ=1.2). Lean mixtures are slower and for
φ=0.6 spherical flame start to be critical with a small crack formation. Figure 4.2 shows
updraft flame speed and pressure rise versus flame radius under stoichiometric
conditions.
2.0
1.8
Sn
P
1.5
1.4
Sn (m/s)
1.6
1.4
1.3
1.2
Pressure (bar)
1.2
1.1
tel-00623090, version 1 - 13 Sep 2011
1.0
1.0
0 5 10 15 20 25 30
Radius (mm)
Figure 4.2 – Flame speed and pressure versus radius for updraft syngas-air mixture at 1.0 bar.
The radius range where the flame speed keeps a spherical pattern is defined between
6 -18 mm, where the pressure rise is only 0.05 bar and no influence of the chamber
wall geometry is observed from flame images.
Figure 4.3 shows schlieren images of downdraft syngas-air mixtures for various
equivalence ratios at 1.0 bar.
From figure 4.3 is possible to observe the spherical pattern of the flame expansion.
Again, stoichiometric mixture is the faster one, followed closely by the rich mixture.
Lean mixtures show to be slower. Another, finding is that downdraft syngas-air flames
are a bit faster than updraft syngas-air flames for every equivalence ratios.
Figure 4.4 shows flame speed and pressure rise during stoichiometric combustion of
downdraft syngas–air mixture. The radius range to explore is defined between 6 -18
mm, where the flame speed keeps a linear behavior. Pressure rise is only 0.03 bar and
no influence of the chamber wall geometry is observed from flame images. This radius
range is kept for the remaining equivalence ratios has similar behavior was found.
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