高速数字全息测量乙醇喷雾火焰中液滴三维位置、粒径及蒸发率

Measurement of 3D Position,Size and Evaporation Rate of Ethanol Spray Droplets in Combustion Using High-speed Digital Holography

喷雾蒸发燃烧的研究对指导发动机燃烧系统设计具有重要意义。本文搭建了高速数字全息系统,在线测量乙醇喷雾火焰中液滴的粒径、三维位置、速度及蒸发率。对喷雾火焰中的液滴进行了统计分析,得到液滴粒径及三维空间分布。燃烧喷雾场液滴的平均粒径为68μm;非燃烧火焰测试区液滴数量多且较密集,燃烧火焰测试区液滴数量少且稀疏.追踪单液滴并处理得到湍流火焰中液滴的运动轨迹及速度。通过研究粒径的平方D2随停留时间ts的变化,测得液滴平均蒸发率为-3.343×10-7 m2/s.

The study of spray evaporation and combustion is of great significance to guide the design of combustion system in the engine.A high-speed digital holography system is developed to measure the particle size,3 D position,velocity and evaporation rate of ethanol droplets in the flame online.The size and 3 D position distribution of ethanol droplets in combustion are displayed.The results show that the average particle size of the droplets undergoing evaporation and combustion is68 μm.There are more droplets at z=30~40 mm and z=60~70 mm than that at z=40~60 mm in the test zone.Tracing a single droplet and processing it to obtain the motion track and velocity of the selected droplet in turbulent flame.The average evaporation rate of the droplet is-3.343×10-7m2/s,which is deduced by analyzing evaporation scales in residence time to the square of the droplet diameter.