Flame characteristics influenced by the angle of burners for non-premixed C3H8/air

The study of micro flame characteristics is an essential basis for developing micro combustors. Therefore, the non-premixed C3H8-air micro flame characteristics were experimentally studied. Flame length, flame shape, and blow-out limit were studied by varying the equivalence ratio, ?, the inlet velocity of C3H8-air, v, and angles of the burner. The results showed ignited non-premixed C3H8-air had three combustion states: no flame, a stable flame, and a blow-out flame. Whether ignited non-premixed C3H8-air could form a stable flame mainly depended on ? and v. In addition, total flame lengths increased with the increase of ? and v firstly. However, when ? increased to a certain value, total flame lengths were independent of ? and only affected by v. Moreover, flame length and shape were affected by the angle of the burner. Instead, the blow-out limit was found to be associated solely with ?, but not the burner angle. The findings of this study provided fundamental data for the development of high-efficiency micro combustors.