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

Chapter 5
80
10
Pmax (bar)
70
60
50
40
30
20
10
Updraft
Dow ndraft
Methane
8
6
4
2
θmax (ms ATDC)
0
0
2.5 5 7.5 10 12.5 15
Ignition Timing (ms BTDC)
tel-00623090, version 1 - 13 Sep 2011
Figure 5.20 – Peak pressure (continuous lines) and peak pressure position (dashed lines)
versus ignition timing for stoichiometric syngas-air and methane-air mixtures.
From figure 5.20 it is clear that the in-cylinder pressure increases as the ignition timing
is retarded. The peak pressure occurs later as the ignition timing decreases. In
opposite to the static chamber combustion, the peak pressure does not represent the
end of combustion. However, it is possible to conclude that the peak pressure occurs
always after TDC.
5.2.4 In-cylinder flame propagation
Burning of a mixture in a cylinder of a SI engine may be divided into the following
phases: (1) spark ignition, (2) laminar flame kernel growth and transition to turbulent
combustion, (3) turbulent flame development and propagation, (4) near-wall
combustion and after burning. Figures 5.21-5.23 show flame propagation images of
stoichiometric syngas-air mixtures combustion and stoichiometric methane-air mixtures
in a RCM, where it is possible to observe these first three phases of combustion.
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