Shock Tube Measurements
and Kinetic Investigation
on the Ignition Delay Times of Methane/Dimethyl Ether Mixtures
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Abstract
In this work, the ignition delay times of stoichiometric
methane/dimethyl
ether (DME) were measured behind the reflected shock waves over a
wide range of conditions: temperatures between 1134 and 2105 K, pressures
of 1, 5, and 10 bar, a DME blending ratio from 0 to 100% (M100 to
M0), and
an argon concentration of 95%. The present shock tube facility was
validated by comparing the measured ignition delay times of DME with
literature values and was used for measurement of the subsequent methane/DME
ignition delay times. The ignition delay times of all mixtures exhibit
a negative pressure dependence. For a given temperature, the ignition
delay time of methane/DME decreases remarkably with the presence of
only 1% DME. As the DME blending ratio increases, the ignition delay
times are correspondingly decreased; however, the ignition promotion
effect of DME is decreased. The calculated ignition delay times of
methane/DME mixtures using two recently developed kinetic mechanisms
are compared with those of measurements. The NUI C4 mechanism yields
good prediction for the ignition delay time of methane. With an increase
of the DME blending ratio, the performance of this model becomes moderated.
Zhao’s DME model yields good prediction for all of the mixtures
studied in this work; thus, it was selected for analyzing the ignition
kinetics of methane/DME fuel blends, through which the nonlinear effect
of DME addition in promoting ignition is interpreted