高温汽油喷雾的宏观形态和液滴粒速粒径

摘要

采用高速相机和PDA(激光相位多普勒风速仪)研究大气环境下汽油从常温到超临界态(最高至376℃)喷雾宏观形态和液滴速度及液滴粒径的变化规律.结果表明:当燃油到达超临界状态时,喷雾形态由常温絮带状结构转变为均匀的云团状结构,与此同时贯穿距和锥角随温度的变化规律完全不同于亚临界状态;喷雾液滴平均速度随着温度的升高先有所增加、后明显减小;当燃油温度低于88℃时,液滴直径分布分散,喷雾中存在直径极大(d>70μm)的液滴,严重影响混合质量,而高温下液滴直径分布集中,所有液滴直径均在15μm以下.%In this paper,high speed camera and PDA (phase Doppler anemometer) system were applied to study the gasoline spray macro morphology and the changes of velocity and size of gasoline spray droplets with fuel tem-perature from 25℃ to 376℃.Results show that when gasoline reaches the supercritical state,its spray changes from ligaments to blurred cloud-like structure.Furthermore,spray penetration decreases while spray angle in-creases with temperature going up under the subcritical state,and both of them will experience a reverse trend when fuel temperature exceeds the critical point.The mean droplet velocities increase slightly before an obvious drop with the increase of fuel temperature.When the fuel temperature is below 88℃,droplet diameter distribution disperse and large droplets (d>70μm) spread in spray.Under higher temperature,the distribution of droplet di-ameter is more concentrated,and the droplet diameter is all under 15μm.