Experimental Study of Gaseous Fuel Inverse Diffusion Flame

Diffusion flame represents one of the most common flame configurations in combustion systems. The main aim of the present work is studying the effects of swirl number and equivalence ratio on the combustion characteristics of liquefied petroleum gas (LPG) for normal diffusion flame (NDF) and inverse diffusion flame (IDF). The effects of different swirl numbers of 0.5, 0.75,1.0, and 1.5 are studied at an equivalence ratio of 1.0. In addition, the effect of different equivalence ratios of 0.75, 1.0, 1.5, and 2.0 at a swirl number of 0.5 are studied. The flame shape, visible flame length, temperature distributions and species concentrations are measured. To study the above parameters, a test rig that consists of the air supply line, fuel supply line, and burner head is designed and constructed. The results showed that, by increasing the swirl number, the visible blue zone is extended and the IDF luminous zone are shortened, and flame length is decreased for IDF and NDF. Moreover, by increasing Φ, the visible flame length increases and the maximum temperature decreases. Also, the concentrations of NO, CO2 and CO are increased until reach their maximum value. While the concentrations of O2 are decreased. IDF emits less CO and NO than NDF, so it is more suitable for environmental preservation.