摘要
基于计算流体动力学(CFD)方法,对搅拌槽中的固液混合过程进行数值模拟,研究不同转速下固液相的分布规律,并得到固体颗粒完全离底悬浮的临界转速.结果表明,对于平直叶涡轮式搅拌器,当安装高度为100 mm时,随着涡轮式搅拌器转速的逐渐增大,槽底的中心沉积区逐渐减小,固体颗粒在300 r/min的转速下达到完全离底悬浮;对于斜叶涡轮式搅拌器,固体颗粒在250 r/min的转速下达到完全离底悬浮.通过与实验结果比较,可以认为CFD方法能够较好地还原搅拌过程.此外,通过改变搅拌器叶片的角度以及搅拌器的安装位置,明确了斜叶涡轮式搅拌器更适合固液混合体系,并且在安装高度为直径的0.5~0.8倍时,能够在较低的临界转速下,使固体颗粒达到完全离底悬浮,明显降低搅拌功耗,具有良好的经济效益.
On the basis of the computational fluid dynamics (CFD) method and the model of Euler two-phase flow, a numerical simulation was developed for the mixing process of two-phase flow of solid-liquid in vessels. The distribution of solid-liquid two-phase flow at different rotation speeds was investigated, yielding the critical rotation speed that makes all the solids be suspended from the bottom. The results showed that the central depositional area was gradually decreased with increasing the rotation speed. For the flat blade turbine agitator, when the rotation speed was increased to be higher than 300 r/min, all the solids were suspended from the bottom. The critical rotation speed was only 250 r/min for the pitched turbine type agitator. In case the installation position was changed, both the two types of agitator can make all the solid particles be suspended from the bottom at a lower rotation speed. We subsequently performed experiments on the mixing of water and silver sand. On the basis of these experiments, the critical rotation speed and the rotation torque were obtained. These results clearly showed that the numerical simulation results were validated by the mixing experiments. Besides, by changing the angle of the blades and the installation position, the mixing experiments and the numerical simulations showed well consistent. It was demonstrated that the pitched turbine type agitator was more suitable for the two-phase mixing of solid-liquid flow. The solid particles can suspend at a lower critical rotation speed in case the installation height is 0.5~0.8 times higher than the diameter of agitator, which can remarkably reduce the mixing power and achieve more economic benefits.
作者
许叶龙
刘迎圆
惠虎
於晔鸿
XU Yelong;LIU Yingyuan;HUI Hu;YU Yehong(School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, China;The College of Information, Mechanical and Electrical Engineering, Shanghai Normal University, Shanghai 200234, China)
出处
《华东理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2019年第4期675-680,共6页
Journal of East China University of Science and Technology
基金
国家自然科学基金(51806145)
关键词
固液混合
临界转速
安装位置
搅拌实验
solid-liquid mixing
critical speed
installation position
mixing experiment
