气泡雾化喷嘴泡状流喷雾特征试验与仿真

建立了气泡雾化喷射可视化试验系统及喷嘴内部和喷雾场中气液流动模型;采用试验和仿真方法对一特定可视化喷嘴的泡状流喷雾特征进行了研究。结果表明,喷雾表面存在气相膨胀凸起现象,气相膨胀凸起宽度随液相流量和气液质量比增加而增大,凸起间距随气液质量比增加而减小;在相同气液质量比下,喷雾锥角随液相流量增加而增大,较高液相流量时液相流量的影响变弱,喷雾贯穿距在较低气液质量比时随液相流量增加而增大,较高气液质量比时则减小;低气液质量比时,喷雾形态受气液质量比影响明显,喷雾锥角和贯穿距随气液质量比增加而增大;液滴碰撞率随喷雾轴向距离增加而减小并逐渐趋于稳定;喷孔出口气液流量脉动对喷孔出口截面附近液滴轴向速度的影响只局限于很短距离内;随着与喷孔出口轴向距离增加,液滴直径分布范围变宽、液滴峰值数量减少,液滴峰值直径和液滴直径分布向大直径方向移动;随着与喷孔出口轴向距离增加,大尺度液滴区内液滴粒径增大,大尺度液滴区的径向范围变宽。

Experiment and Simulation on Spray Characteristics of Effervescent Atomizer within Bubbly Flow

A visual effervescent spray system and a gas liquid flow simulation model of atomizer interior and spray field were established to investigate spray characteristics of bubbly flow. The results showed that there was a gas phase expansion on spray surface, and the width of the gas phase expansion was increased with the increase of liquid mass flow rate and gas liquid mass ratio, distance between two expansions was decreased with the increase of gas liquid mass ratio. At the same gas liquid mass ratio, the spray cone angle was increased with the increase of liquid mass flow rate, and the influence of the liquid mass flow rate became weak at high liquid mass flow rate. The spray penetration distance was increased with the increase of liquid mass flow rate at low gas liquid mass ratio, while decreased at high gas liquid mass ratio. When the gas liquid mass ratio was low, the spray shape was apparently influenced by the gas liquid mass ratio, and the spray cone angle and penetration distance were increased with the increase of gas liquid mass ratio. As axial distance of the spray was increased, the droplet collision frequency was decreased and gradually became stable. The influence of gas liquid mass flow pulsation at atomizer outlet on the droplet axial velocity around the cross section of the atomizer outlet was limited to a very short distance. With the axial distance to the atomizer outlet increased, the distribution range of droplet size was widened, the number of peak droplets was decreased, and the peak size of droplet and droplet size distribution was moved to the direction of large size. With the increase of the axial distance to the atomizer outlet, droplet size in large scale droplet area was increased, the radial range of large scale droplet area was widened.