高湿度気流中における液滴火炎内のすす生成特性(熱工学,内燃機関,動力など)  [in Japanese] Soot Formation in Combustion of Single Fuel Droplets in Humid Air Flow(Thermal Engineering)  [in Japanese]

An experimental study is performed to provide the empirical data on soot concentration profile in a fuel droplet flame and to get the fundamental knowledge on the effect of water content in the droplet and the atmospheric gas on the soot formation in droplet flames. The laser light scattering technique is applied for non-intrusive qualitative measurements of soot concentration in fuel droplet flames. Measurements are conducted along the diametrical line passing through the front stagnation point of a luminous envelope flame formed around a droplet of various kinds of fuels in the steady stream of the mixture of air and water vapor with uniform profiles of velocity and temperature. The results indicate that the highly sooting region is located deep inside the flame edge. The peak signal of soot decreases with an increase in the velocity of the ambient flow. Increase in oxygen concentration in the ambient flow enhances soot formations in the droplet flame, and the peak position of soot moves outwards. Water vapor in the ambient air stream has negative effects on soot production in the droplet flame and increase in the water concentration results in decrease in the peak concentration of soot. Although water content in an emulsified fuel droplet also has the negative effect on soot reduction, the effect is smaller than that of the ambient water vapor in the flow.