Combustion Properties of a Wick Flame

Abstract

Some properties of a kerosene wick flame such as flame appearance, flame temperature and fuel consumption were measured for different velocities of air flow parallel to the wick, temperatures of the air stream, thicknesses of the wick and heighs of the wick exposed to the stream.A yellow flame similar to a gaseous diffusion flame is obtained when the stream velocity is lower than 1m/sec. As the velocity increases, the flame becomes shorter and highly luminous at first, and then transition to a blue flame similar to a gaseous premixed flame occurs at the air velocity of 2-3m/sec. This transition is probably due to rapid mixing of fuel vapour and air by increased eddy diflusion. When the air velocity increases further, the flame begins to oscillate and finally it blows off at the velocity higher than 10 m/sec.For practical use, the allowable air velocity is limited to the range for a highly luminous yellow flame and a blue flame without oscillation, fuel consumption being nearly constant in this range.The increase of thickness of the wick and air temperature decreases the air velocity at which the flame begins to oscillate. Height of the wick exposed to the stream has the same effect when evaporation of fuel from that portion is increased.Maximum flame temperatures measured by a small thermocouple are about 1400°C for both highly luminous and stable blue flames.