A Study on Mass Transfer between Recirculation Zone and Outside Flow of Annular Premixed Flame

Abstract

A mass transfer between recirculation zone and outside flow of an annular premixed propane flame was investigated experimentally using MgO powder tracing method and NaCl flame emission. The loacation of the stagnation point in the recirculation zone of the burning flow moved gradually from the nozzle exit with an increase of the gas exit velocity and became constant independently of the gas exit velocity in the very high velocity region. In the region of lower gas exit velocity, the average residence time of the fluid in the recirculation zone of the burning flow was evidently smaller than the time of the cold flow (air) at the same exit velocity, and both residence times decrease gradually with an increase of the gas exit velocity and became a same constant value in the region of very high velocity. Thus, the rate of mass transfer through the surface of the recirculation zone of a high velocity burning flow issuing from the annular nozzle was estimated by the data on the annular air jet.