반밀폐 연소공간 내 동축관 형상에 따른 DME-공기 확산화염의 안정화 특성Stabilization Characteristics of DME-Air Diffusion Flames Depending on the Configuration of the Fuel-Air Tubes in Half Closed Combustion Spaces
The effects of configuration of fuel and air tubes on the flame stabilization were experimentally
investigated in half-closed combustors. Flame behaviors and stabilities of methane, propane, and DME flames
were compared by changing tube diameters and the locations of the fuel and air tubes. It was found that
flammability limits are significantly affected by the outlet boundary condition, which disturbs compositions of
burned and unburned mixtures near the flame base. And it was found that there exist critical inner tube heights,
over which flame stability is determined only by the fuel flow rate. Conclusively, flame stabilization is
governed by the flame propagation velocity in an ordinary mixing flow and the non-uniform mixture
concentration in the combustion space which is affected by flow recirculation and the combustor
configuration. The compositions of NOX and CO were compared to know basic characteristics of methane,
propane, and DME flames.