An Experimental Study of Optimum Angle of Air Swirler Vanes in Liquid Fuel Burners

The present work shows that how the angle of an air swirler vane affects the combustion characteristics of liquid fuels such as flame temperature, radiation heat flux, combustion efficiency, and pollutants' emission. It finds out an optimum angle of vane based on flame characteristics. Three vanes with angles of 0 deg, 40 deg, and 80 deg which induced low and high-swirl intensities in air stream were investigated, and the combustion characteristics of flame were quantified. The flame temperature was measured by an S-type thermocouple, and a Testo 350 XL gas analyzer was used to determine the CO and NO pollutant concentrations. Also, gravity method was used to gauge the soot concentration along the furnace, and a SBG01 water cooled heat flux sensor determined the flame radiation. The results indicate that the angle of the swirler vane has significant effects on temperature, combustion efficiency, and NO and CO pollutants' emission. Most importantly, there is an optimum angle for the swirler vane. At the optimum angle, the optimum combination of the contact area and time maximizes the mixing rate of the inlet air and the fuel jet. Consequently, at the optimum angle, the mean temperature, radiation heat flux, and combustion efficiency are higher than at small and large swirl angles and soot, CO and NO_x emissions are at their minimum states.