Flame Stability of Methane/Air Mixture in a Heat-Recirculating-Type Mesoscale Channel with a Bluff-Body

To extend the stable combustion range of micro-combustor, a heat-recirculating-type planar micro-combustor fitted with a bluff-body was proposed in the present work. Numerical simulation on CH4/air premixed combustion in this combustor was performed and the stable combustion range was determined, which showed that the blow-off limit increases with the equivalence ratio and the lower flammability limit was extended. Effect of the equivalence ratio and inlet velocity on combustion efficiency and maximum temperature were investigated. The numerical results showed that combustion efficiencies were higher than 99%, and the maximum temperatures were larger than the corresponding adiabatic flame temperature due to the excess enthalpy combustion effect. However, flashback emerged when the inlet velocity was too small and the equivalence ratio is relatively high.