空气辅助喷射闪急沸腾喷雾特性试验

在定容弹内利用高速相机和相位多普勒粒子分析仪（PDPA）研究了环境压力和燃油温度对空气辅助喷射系统喷雾特性的影响。试验环境压力的变化范围为0.01MPa到0.1MPa,燃油温度的变化范围为25℃到100℃。试验结果表明:随着环境压力的减小,燃油喷雾逐渐从冷态过渡到闪急沸腾状态,在喷嘴出口处喷雾气泡急剧增加。当环境压力小于0.02MPa时,喷雾处于闪急沸腾状态,液滴速度增加,粒径减小,在喷雾近端出现喷雾膨胀现象；随着燃油温度的上升,液滴表面张力减小,液滴易于破碎。当燃油温度达到100℃时,喷雾处于闪急沸腾状态,喷雾远端出现喷雾膨胀现象。 

Experiment on spray characteristics of air-assisted injection under flash boiling conditions

The effects of ambient pressure and fuel temperature on spray characteristics of air-assisted injection system were investigated by using high-speed photography and phase Doppler particle analyzer (PDPA) in a constant volume chamber. The ambient pressure ranged from 0.01MPa to 0.1MPa, and the fuel temperature ranged from 25℃ to 100℃ during the experiment. The experimental results showed that spray condition transferred from the non-flash boiling to flash boiling gradually with the decrease of the ambient pressure that induced the intensified bubble bursting at the nozzle exit. When the ambient pressure was less than 0.02MPa, the spray was in flash boiling condition, bringing about the increase of the droplet velocity, the decrease of the droplet diameter and the spray expansion in the near field. Meanwhile, the rising fuel temperature led to the decrease of the fuel surface tension, which can accelerate the break of the droplet. As the fuel temperature reached 100℃, when the spray was in flash boiling condition, the spray expansion occurred in the far field.