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

Experimental study of engine-like turbulent combustion
more favorable conditions than those existing in real engines (Strozzi et al., 2008),
specially the spontaneous ignition (Brett et al., 2001). RCM can operate under two
different modes: single compression and compression – expansion.
The study of the compression process in a RCM operating without combustion is useful
to identify different parameters related with its operation, namely the heat transfer to
the walls. Once determined, these parameters can also be used during the usual firing
cycle. In fact, a common practice in engine testing for combustion diagnostic is, prior to
the usual firing tests, to test the engine in motored conditions, with air as the only
working gas (Lapuerta et al., 2003).
5.1.1 Sensibility analysis
tel-00623090, version 1 - 13 Sep 2011
In this section a sensibility analysis is made with the objective of evaluating the
influence of errors in measurement techniques and in the estimation of various
parameters on the main experimental results. In this analysis the chamber wall
temperature is considered as constant.
5.1.1.1 TDC position
In order to determine the precision of the RCM top dead center (TDC) position, a
position sensor was placed at TDC and various tests performed without combustion in
order to eliminate the effect of the spark time scattering. The analysis of the TDC signal
for the whole single compression experiments without combustion performed with
syngas-air and methane-air mixtures enables to define a typical scattering of the TDC
position on less than 1.67 ms. Considering that the compression stroke duration is 44
ms, this gives an overall uncertainty of 3.8% on the TDC position. In order to determine
the influence of this scattering on pressure signal for the updraft-syngas case both
signals are plotted in figure 5.1.
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