Emission of nitrogen oxides (NOx) caused by exhaust gas from airplane is computed approximately 60% at high-altitude. Lean premixed-prevaporized combustion is given for one of methods of NOx reduction in jet engines. Improvement of spray characteristics before combustion is important for fuel injection of jet engine, which is leaded to redaction of exhaust gas emission at high-load conditions and high-dispersion of fuel. However, air-blast atomizer has the following characteristics that velocity of atomizing air decreases with an increase in rapidly large droplets of spray. Therefore, it is required that uniform and small droplets are obtained independent of atomizing air flow rate. The purpose of this study is that uniform and small droplets are obtained under low atomizing air velocity, to improve spray characteristics and homogeneous droplets is generated at wide region of spray. It was investigated that effects of shapes of supplying passage for atomizing air of air-blast atomizer on spray characteristics. As a results, it was cleared that excellent spray characteristics, that is, large spray angle of about 140 deg. and relatively small Sauter mean diameter of about 40 μm, was obtained by using the air-blast atomizer which was designed in this study.

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