Comparison of Methane Combustion Mechanisms Using Shock Tube and Rapid Compression Machine Ignition Delay Time Measurements

Methane is the major
component of natural gas, which is one of
the most widely used fuels. A large number of shock tube (ST) and
rapid compression machine (RCM) ignition delay measurements are available
in the literature for validating its detailed combustion mechanisms.
A large set of experimental data was collected for methane combustion:
ignition studies in STs (4939 data points in 574 datasets) and in
RCMs (582/69). In total, 5521 data points in 643 datasets from 76
publications were collected, covering wide ranges of temperature T, pressure p, equivalence ratio φ,
and diluent concentration. For a quantitative assessment of methane
combustion models, a least-squares function is used to show the agreement
between measurements and simulations. Thirteen recent methane combustion
mechanisms were tested against these experimental data, and the dependence
of their predictions on the types of experiments and the various experimental
conditions was investigated. The mechanism comparison results show
that most mechanisms could well reproduce the experimental ignition
delay times (IDTs) measured in STs. IDTs measured in RCMs and STs
at low temperatures (below 1000 K) could also be well predicted by
several mechanisms. SanDiego-2014, Caltech-2015, Aramco-II-2016, and
Glarborg-2018 were found to be the most accurate mechanisms for the
simulation of methane combustion under ST experimental conditions,
while Aramco-II-2016 had the smallest prediction error under RCM conditions.
Local sensitivity analysis was carried out to determine the effect
of reactions on the simulation results obtained under given experimental
conditions and to identify the critical reaction steps for improving
the methane combustion models.