幂律流体双股碰撞雾化特征的实验研究

Atomization characteristics experiment of impinging jets with power-law fluid

摘要:

为深入研究双股射流碰撞系统的雾化特性，基于双股射流碰撞雾化实验台，采用PIV测速仪，通过改变双股射流的射流不对称性、添加氮气气流扰动以及添加金属铝粒子，来实验探究上述因素对于幂律流体雾化的影响.实验结果表明：韦伯数较小时，幂律流体以一定偏心度碰撞会形成链状液膜，链结长度随偏心度增大而减小；当双股射流以不同长度撞击时，幂律流体会出现鱼骨模式，该现象在0.15%卡波姆凝胶中较为明显；添加气流扰动能增大幂律流体液膜表面波的强度，导致液膜宽度变薄、液膜边缘提前破裂，并且当韦伯数较小时，液滴索太尔平均直径减小；添加金属粒子使幂律流体强度变低，最大破碎长度变小，提前进入各个破碎模式，更早达到液滴平均直径收敛值.采用一定的偏心度，适当加入气流扰动和金属粒子，有助于改善幂律流体雾化性能.

Abstract:

On the impinging injector platform, the effects of jet asymmetry, airflow disturbances and metal particles on the atomization characteristics were studied by PIV (particle image velocimetry) technology. The experimental results indicate that when the two asymmetric jets impinges at low weber number, the chain sheet appears, and as the eccentricity increases, the link-length decreases. Fish bones regime can be found when the jet is with different length. Additional airflow disturbances can increase the atomization quality, because when the surface wave's intensity is increased, it will break up more easily, as a result, the width of fluid sheet and the SMD (sauter mean diameter) of droplets decrease. When power-law fluid contains aluminum particles, its strength is smaller and its max length decreases obviously. The droplets' SMD convergence does not change, as well, the SMD reaches convergence in shorter time. In conclusion, proper jet asymmetry, airflow disturbances and metal particles can improve impinging jets' atomization performance with power-law fluid.