Experimental and theoretical study on the flow, mixing, and combustion characteristics of dimethyl ether, methane, and LPG jet diffusion flames

The flow and mixing, flame length, width, and volume, and stability behaviors of DME, methane, and LPG jet diffusion flames are comparatively studied. Five fuel nozzle diameters (d(f) = 1.12, 1.98,330,4.20, and 6.11 mm) and a wide range of fuel jet velocities (u(f)) ranging from laminar regime (LR) to blow-out (BO) were included to investigate their effects on the flame behavior systematically. For each fuel flame, with the increase in d(f), both the transitional and BO fuel jet Reynolds numbers (Re-f) increase; and the corresponding u(f) decreases accordingly. The transitional and BO Re-f and u(f) of the DME flames are similar to those of the LPG flames. Compared with DME and LPG, the methane flames transit and are blown out at lower Re-f and higher u(f). At the LR, the flame length (FL) is proportional to Re-f. While at the fully-turbulent regime (FTR), the FL remains constant. Besides, the flame width (FW) hardly varies with u(f), either at the LR or at the FTR; but it increases rather quickly at the laminar-turbulent transitional regime (LITR). Finally, new forms of correlations for the dimensionless flame length, width, and volume of DME, methane, and LPG flames are developed. (C) 2014 Elsevier B.V. All rights reserved.