A coannular burner is used for our experimental study of the coflow diffusion flames of different fuels. The inner and outer diameters of the steel fuel tube are 10.90 mm and 12.70 mm, respectively. The fuel nozzle is centered in an air annulus of 90 mm inner diameter (for more details, see O.L. Gülder, D.R. Snelling, R.A. Sawchuk, Symp. (Int.) Combust. 26 (1996) 2351–2358.). A clear acrylic tube, of 152.4 mm (6 in.) inner diameter and 304.8 mm (12 in.) height, protects the flame from air movements in the room. A ceramic honeycomb on top of the chimney prevents air circulation inside the enclosure. The burner sits on manual translation stages which allow accurate positioning in horizontal and vertical directions.
OEM coil heaters are installed around the fuel tube under the metal mesh to control the temperature of the fuel. Coil heaters are essential to avoid fuel condensation when liquid fuels are used.