Shock Tube and Kinetic Modeling Study of Cyclopentane and Methylcyclopentane

Ignition
delay times for 1% cyclopentane/O2 and 0.833%
methylcyclopentane/O2 mixtures diluted by argon were measured
behind reflected shock waves at pressures of 1.1 and 10 atm, with
equivalence ratios of 0.577, 1.0, and 2.0, and in the temperature
range from 1150 to 1850 K. Submechanisms for cyclopentane and methylcyclopentane
were developed and added to the JetSurF2.0 mechanism for the kinetic
interpretation of cyclopentane and methylcyclopentane oxidation chemistry
at the high temperature region. Simulations with the model exhibit
fairly good agreements with the measured ignition delay times of both
cyclopentane and methylcyclopentane under all tested conditions. Cyclopentane
shows longer ignition delay time than methylcyclopentane, especially
for the fuel-lean mixture. Reaction pathways and sensitivity analyses
were conducted to get insights into the oxidation process of cyclopentane
and methylcyclopentane. Then, three factors are given for the effect
of a cyclic ring and substitution of a methyl group. Substitution
of a methyl group weakens the C–C bond to motivate fuel unimolecular
decomposition. The shape of the cyclic ring determines the chain alkyl
radicals, affecting regeneration and accumulation of H radical. The
presence of a methyl group also leads to different alkyl radicals.