  In this study, methane detonation propagation in dilute coal particle
suspensions is studied based on Eulerian-Lagrangian method. Two-dimensional
configuration is considered, and a skeletal chemical mechanism (24 species and
104 reactions) is applied for methane combustion. The gas and particulate phase
equations are solved using an OpenFOAM code for two-phase compressible reacting
flow, RYrhoCentralFOAM. The effects of char combustion on methane detonation
dynamics are investigated and devolatized coal particles are modelled. The
results show that propagation of the methane detonation wave in coal particle
suspensions are considerably affected by coal particle concentration and size.
Detonation extinction occurs when the coal particle size is small and
concentration is high. The averaged lead shock speed generally decreases with
increased particle concentration and decreased particle size. Mean structure of
methane and coal particle hybrid detonation is analysed, based on the gas and
particle quantities. It is found that char combustion proceeds in the subsonic
region behind the detonation wave and heat release is relatively distributed
compared to that from gas phase reaction. Moreover, for 1 {\mu}m particle, if
the particle concentration is beyond a threshold value, detonation
re-initiation occurs after it is quenched at the beginning of the coal dust
suspensions. This is caused by hot spots from the shock focusing along the
reaction front in a decoupled detonation and these shocks are generated from
char combustion behind the lead shock. A regime map of detonation propagation
and extinction is predicted. It is found that the re-initiation location
decreases with the particle concentration and approaches a constant value when
the concentration exceeds 1000 g/m3. The results from this study are useful for
prevention and suppression of methane/coal dust hybrid explosion.
