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

• Flow, mixing, length and width behaviors of jet flame were theoretically studied.
• Correlations of DME, methane, and LPG flame length, width, and volume were developed.
• Blow-out limits of DME, methane, and LPG jet flames were obtained.

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 (df = 1.12, 1.98, 3.30, 4.20, and 6.11 mm) and a wide range of fuel jet velocities (uf) 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 df, both the transitional and BO fuel jet Reynolds numbers (Ref) increase; and the corresponding uf decreases accordingly. The transitional and BO Ref and uf 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 Ref and higher uf. At the LR, the flame length (FL) is proportional to Ref. While at the fully-turbulent regime (FTR), the FL remains constant. Besides, the flame width (FW) hardly varies with uf, either at the LR or at the FTR; but it increases rather quickly at the laminar-turbulent transitional regime (LTTR). Finally, new forms of correlations for the dimensionless flame length, width, and volume of DME, methane, and LPG flames are developed.

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