Combustion of gaseous and liquid fuels in meso-scale tubes with wire mesh

Combustion of gaseous and liquid fuel in meso-scale tubes with wire mesh was studied experimentally. For C₃H₈/air mixtures, the flame can be stabilized near the mesh inside the tube without external heating even for smaller tube than the classical quenching diameter by heat recirculation from the burned gas to the unburned gas through heat conduction in the wall and mesh. The mesh enhances heat transfer from the heated wall to the unburned gas. For tubes larger than the classical quenching diameter, the flame can be stabilized inside the tube even outside the flashback limit by the heat recirculation. Within a specific range of flow velocity, the flame propagates at relatively high speed and extinction occurs near the mesh, but the flame can be stabilized near the mesh if the condition is gradually shifted from another condition with a stabilized flame. Therefore, the mesh can act as a combustion inhibitor or an enhancer. The two types of burning behavior are discussed based on two steady-state flames; normal flame and weak flame predicted by other researchers. Next, combustion of electro-sprayed ethanol/n-heptane mixtures inside a meso-scale tube with d = 3.5 mm with a single mesh and double meshes was studied. The flame can be stabilized near the mesh without external heating. If droplets passing through the mesh directly interact with the flame, heat loss and asymmetric flame shape occurs. The flame stabilization region with double meshes is larger than that with a single mesh and comparable to that for gaseous fuel combustor except for the wall wetting region.