On the influence of nozzle geometry on jet diffusion flames under cross-wind

Abstract

Four nozzle types were used to investigate the blow-out limit, flame shape, flame mean length, and flame tilt angle of jet diffusion flames under cross-wind conditions. The experimental results revealed that the nozzle geometry had a minor influence on the flame blow-out limit when the fuel jet velocity was low. As the fuel jet velocity increased, the nozzle geometry had a significant influence on the flame blow-out limit, the blow-out velocity of the triangle nozzle was the maximum, and the rectangular nozzle was minimum. The nozzle geometry had a significant influence on the down-wash and lift-off of the flame under cross-wind conditions. The triangle nozzle was prone to the appearance of the down-wash phenomenon, and the rectangular nozzle flame easily exhibited the lift-off phenomenon. Additionally, the effect of the nozzle geometry on the flame blow-out limit and flame shape was explained from a moment of inertia viewpoint. The flame length of the rectangular and cross nozzles monotonously increased with the increase of the momentum flux ratio of the fuel jet to the cross-wind. However, two growth curves occurred as the flame length of the circle and triangle nozzles increased with the momentum flux ratio of the fuel jet to the cross-wind. Additionally, for the jet diffusion flames under cross-wind conditions, the nozzle geometry exerted a smaller effect on the flame tilt angle.