Stability of premixed tubular burner flame in horizontal-configuration with opposing air-flow

This paper discusses stability of horizontally fired premixed tubular burner flames with impinging opposed air-flow on the flame cone. Under the action of opposing air-flow velocity, the conical flame is transformed into a mushroom-shaped tented flame with its central cylindrical portion and widened convex flame apex. The experimental data obtained show that high-stability, fuel-rich premixed tubular burner flame operates over narrow range of equivalence ratio φ from 1.4 to 1.6 for the impinging opposed air-flow velocity of 2 m/s. For the fuel-rich flame of equivalence ratio φ=1.5, the blow-off velocity is seen to be two times higher than that for the flame operating without the opposing air-flow. The high flame stability observed is explained in line with the concept of flame-stretch theory. The enhanced flame stability is attributed to the re-circulating combustion product gases around the burner rim due to the tented flame configuration. The heat transfer caused from the recirculating hot gases to the flame base helps in overcoming the aerodynamic quenching occurring above the burner rim, thereby enabling the flame to withstand higher blow-off velocity. The possible use of the present high-stability, fuel-rich flame in developing low-pollutants emissions burner system is also highlighted.