  Strategies and recommendations for performing skeletal reductions of
multicomponent surrogate fuels are presented, through the generation and
validation of skeletal mechanisms for a three-component toluene reference fuel.
Using the directed relation graph with error propagation and sensitivity
analysis method followed by a further unimportant reaction elimination stage,
skeletal mechanisms valid over comprehensive and high-temperature ranges of
conditions were developed at varying levels of detail. These skeletal
mechanisms were generated based on autoignition simulations, and validation
using ignition delay predictions showed good agreement with the detailed
mechanism in the target range of conditions. When validated using phenomena
other than autoignition, such as perfectly stirred reactor and laminar flame
propagation, tight error control or more restrictions on the reduction during
the sensitivity analysis stage were needed to ensure good agreement. In
addition, tight error limits were needed for close prediction of ignition delay
when varying the mixture composition away from that used for the reduction. In
homogeneous compression-ignition engine simulations, the skeletal mechanisms
closely matched the point of ignition and accurately predicted species profiles
for lean to stoichiometric conditions. Furthermore, the efficacy of generating
a multicomponent skeletal mechanism was compared to combining skeletal
mechanisms produced separately for neat fuel components; using the same error
limits, the latter resulted in a larger skeletal mechanism size that also
lacked important cross reactions between fuel components. Based on the present
results, general guidelines for reducing detailed mechanisms for multicomponent
fuels are discussed.

Chemical Physics