Structure of Spray Flames in a Hot Air Stream.

Abstract

Behavior of a spray combustion in a hot air was studied experimentally. A kerosene spray was injected from swirl atomizer into a hot air stream. The air temperature was controlled from room temperature to 1 100 K which was higher than the self-ignition temperature of a kerosene spray. Flame shape and temperature distribution were measured to characterize the spray combustion appeared in the hot air stream. Flow state around the spray was visualized by a Schlieren method to analyze the behavior of the air entrainment into the flame. Furthermore, Mie scattering from the spray droplets by irradiation of the laser beam was observed to visualize the spray concentration in a flame. As the result, ignition point was shifted to the upstream side with an increase of air temperature. When the air temperature became higher than 800 K, the blue flame appeared at the bottom portion of the flame. Penetration of the spray became shorter with an increase of air temperature. Spatial distribution of the spray which were not vaporized in a flame was strongly affected by the air temperature.