Measured ignition delay times for lean (U = 0.5) 2-butanone/O2/
Ar mixtures are plotted in Fig. 5 and compared with model predictions.
Figure 5 reveals similar trend as were seen for the stoichiometric
case in Fig. 3, where the pressure dependency is relatively low
and the Serinyel et al. [1] model over-predicts the ignition delay
times for both pressures although the difference between the calculations
and measurements is smaller for the higher pressure case.
Similarly, the discrepancy between the experimental data and the
calculations is reduced with the updated Serinyel et al. [1] model.
Also, the ignition delay times are shorter for lean mixtures
(U = 0.5) compared to the stoichiometric (U = 1) case. This is expected
since the chain branching reaction H þ O2 () O þ OH is
dominant in 2-butanone/O2/Ar igniting systems at the high temperatures
of this work. The ignition delay times of 2-butanone/O2/Ar
mixtures studied in this work scale up with the pressure according
to the following expression: