气泡雾化喷嘴雾化分布特征的研究

Study on atomization distribution characteristics of effervescent atomizing feed nozzle

用水和压缩空气在常压下对气泡雾化喷嘴进行冷态试验,研究了水平喷射时气泡雾化喷嘴雾化流中粒子分布的特征以及气液质量百分比(气液比)对粒子分布的影响。结果表明,气泡雾化和气动雾化过程雾化流中粒子的分布存在明显不同,气动雾化过程大颗粒集中在雾化流的中心部位,而气泡雾化过程的大颗粒集中在雾化流的中下部位。气泡雾化喷嘴雾化过程雾化流中粒子分布与粒子的体积分布存在很大的差异,在试验条件下,粒子分布有着近似正态分布的特征,峰值在50μm附近;粒子体积分布的峰值后移,峰值在75μm以上,且大颗粒的体积分数远大于大颗粒数目所占的分数,更能体现喷嘴的雾化效果。提高气液比改善雾化效果不仅体现在平均粒径的大小,更重要的在于对粒子分布产生的影响,气液比提高时,小颗粒和大颗粒所占的体积分数减小,雾化流的分布更好。在SMD(Sauter Mean Diameter)约为70μm,进水量适中(400 kg/h)时,雾化流可以取得较好的粒子体积分布。

The characteristics of particle distribution and the impacts of gas liquid ratio on the distribution of particles in the atomization process of effervescent atomizing nozzle are investigated by using water and com- pressed air at atmospheric pressure. The results show that there is an obvious difference of the particle distri- bution between the pneumatic and effervescent atomizing processes, in which big particles are concentrated in the central area and the upper part on the cross section respectively. There is a great difference in the distribu- tion of particles and particle volume distribution in the effervescent atomizing process under the experimental conditions. The former has characteristics of approximate normal distribution and peak near the 50μm. The latter＇ s peak is over 75μm, the peak shift, and the volume fraction of large particles far outweigh the fraction of large particles, which can better reflect the atomizing effect. When the gas-liquid ratio is increased to im- prove atomization, not only it is reflected in the size of the average particle size, but also the impact on the particle distribution is more important. The atomization flow distribution becomes better with the decreased vol- ume fraction occupied by the small and large particles. When the SMD （Sauter Mean Diameter） is about 70 μm, the better result can he achieved bv keeDing an appronriate amount of inlet water（about 400 kg/h）.