Experimental investigation on burner lip thickness effect on the liftoff and blowout velocities of jet diffusion flame

This experimental study addresses issue on the effect of burner lip thickness on the liftoff and blowout velocities of jet diffusion flame discharging into quiescent air. Burner tubes of two kinds of inner diameter (2 and 3 mm) with a wide range of lip thicknesses (0.25–16.5 mm) are implemented with methane or propane jet diffusion flame, respectively. The results show that the burner lip thickness has a profound effect on flame liftoff velocities, especially the blowout velocities. With the increase of the lip thickness, the blowout velocities firstly increase, then decrease and lastly remain unchanged. Specifically, the blowout velocities of 2 and 3 mm inner diameters tubes reach the maximum values when the corresponding burner lip thicknesses are 2 and 1.5 mm, respectively. In addition, compared with free (unconfined) jet diffusion flame, the jet confinement results in slight reductions of flame liftoff and blowout velocities. The existence range of lifted flame issuing from larger diameter burner tube is wider than that of smaller diameter burner tube. The existence range of propane lifted flame is wider than that of methane.