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

Experimental study of engine-like turbulent combustion
-5.0 ms -3.75 ms -2.5 ms -1.25 ms TDC
1.25 ms 2.5 ms 3.75 ms 5.0 ms 6.25ms
(a)
-6.25 ms - 5.0 ms -3.75 ms -2.5 ms -1.25 ms
tel-00623090, version 1 - 13 Sep 2011
TDC 1.25 ms 2.5 ms 3.75 ms 5.0 ms
(b)
-12.5 ms -11.25 ms -10.0 ms -8.75 ms - 7.5 ms
-6.25 ms - 5.0 ms - 3.75 ms -2.5 ms -1.25 ms
TDC 1.25 ms 2.5 ms 3.75 ms
(c)
Figure 5.23- Direct visualization of stoichiometric methane-air flame in a RCM for various
Ignition timings. (a) 5 ms BTDC; (b) 7.5 ms BTDC; (c) 12.5 ms BTDC.
Pictures of the initial phase of combustion show an initially quasi-spherical, relatively
smooth flame kernel for syngas compositions and methane cases for the various
ignition timings. The laminar behavior of the flame remains longer time as the ignition is
made far from TDC. In the case of ignition timing at 12.5 ms BTDC, the flame kernel
grows and experience flattening when piston is close to TDC position before the
transition to turbulent combustion.
Because the combustion continues in the expansion stroke, it is not possible to
determine from direct flame visualizations of the combustion chamber the combustion
duration. However, estimation about the rapidity of the combustion can be made from
figures 5.21-5.23. It is observed that the time at which the flame occupies the entire
chamber increases as the igniting timing increases for the whole fuels. This
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