The evolution of flame geometrical characteristics and air entrainment of inclined jet flames

Abstract

This paper reported the jet fire issuing from different angles, a common hazard in pipeline leakage accidents during the gas storage and transportation process. The flame geometrical profiles including flame projection length in the horizontal direction, vertical height from the nozzle position and flame trajectory length as the essential parameters to evaluate jet fire risk and design safety distance between process equipment were measured experimentally. The result shows that flame projection length in the horizontal direction first increases to a maximum value at the horizontal jet flame condition and then decreases, flame vertical height from the nozzle position increases monotonously and the length of flame trajectory first decreases and then increases with the increasing inclined angle from downward to upward. Then, the normalized flame trajectory and its length for different inclined jet flames were obtained by plotting the flame tip location parameters normalized by a characteristic length representing the interaction between jet flow momentum and buoyant force generated by temperature variation. Finally, the air entrainment coefficients for different inclined jet flames were quantified by an integral model derived from the conservation equations showing a trend of first increase and then decrease with the increasing inclined angle from negative to positive. This work provides a good reference for quantifying the flame size of jet flame in inclined conditions.