Experimental investigation on non-premixed methane/air combustion in Y-shaped meso-scale combustors with/without fibrous porous media

Diffusion methane-air flames in Y-shaped meso-scale combustors of three different diameters (i.e., d = 4, 5 and 6 mm) were experimentally studied. The impact of adding fibrous porous media on mixture ignitability, flame stability and flammable range were systematically investigated. Without porous media, the mixture can only be ignited at positions farther than a certain distance, which was defined as ignition distance in this paper. The ignition distance increases with an increasing inlet velocity and decreases with a decreasing channel diameter. The flame cannot be stabilized and propagates downstream with an inclination angle. The propagation velocity increases with the increase of inlet velocity or with the decrease of channel diameter. With the addition of porous media, the mixture can be ignited near the splitter due to improved methane/air mixing. Moreover, the flames become more stable and stationary flames were observed under lower velocities in the combustors of d = 5 mm and 6 mm with fibrous porous media. Furthermore, the application of porous media can significantly expand the flammable range. In summary, the combustion performances can be notably improved by the application of fibrous porous media.