幂律流体旋流射流的喷雾特性实验

Experiment on the Spray Characteristics of Power Law Fluid in a Swirl Injector

采用高速摄影技术和三维相位多普勒分析技术,测量了幂律流体旋流射流的破碎形貌、液滴速度和粒径分布,获得了其破碎特征及规律.结果表明,幂律流体旋流射流随喷射压力增加可以划分为3种射流模式,即带旋转的圆柱射流模式、液线液滴共存模式和充分发展模式.黏性越大的流体,要达到同样的射流模式所需要的喷射压力也越大.液滴的轴向速度w、径向速度u和索特平均直径(SMD)在径向各位置呈中心小两侧大的分布规律,切向速度v接近于零.三维速度在轴向各位置随z的增加均有不同程度的减小,SMD也有减小的趋势.不同压力对轴向速度w的影响更为明显,且更多地影响了液滴的二次破碎.

High-speed photography and 3-D phase Doppler methods were used to obtain the swirl jet breakup images,droplet velocities and size distribution of power law fluid and analyze its breakup characteristics.Results show that the spray patterns could be categorized into three types with injection pressure increasing:rotating cylindrical jet,coexistence of ligaments and droplets,and fully developed spray pattern.Fluid with greater viscosity needs higher injection pressure to achieve the same spray pattern.The axial velocity w,radial velocity u and Sauter mean diameter(SMD)of droplets are small in central area and big on both sides at different radial positions;the tangential velocity v is close to zero.The three-dimensional velocity and SMD decrease to some extent with the increment of z.The injection pressure has an obvious influence on axial velocity w and droplets’ secondary breakup.