Numerical simulation of solid–liquid mixing characteristics in a tank stirred by an improved double-layer 4-pitched blades impeller

Abstract

Aiming at the problems of low mixing efficiency and poor uniformity of solid–liquid dispersion caused by double-layer 4-pitched blades turbine, a new impeller is obtained by optimizing the structure of the traditional blade. In order to efficiently apply the improved double-layer 4-pitched blades impeller to the mixing process of DNAN-based explosives, this paper takes the new impeller as the research object, investigating the solid–liquid suspension characteristics of the stirred tank through computational fluid dynamics (CFD). A stirring experiment is designed, and a conductivity probe is employed to measure the local solid particle concentration. After validating the CFD model by experimental results, numerical analysis is successfully used to examine the impacts of stirring speed, layer spacing, impeller height from the bottom and impeller inclination angle on the solid–liquid mixing quality. Results show that the increase of rotational speed can significantly enhance the solid–liquid dispersion efficiency. Meanwhile, the blade structure parameters have an important influence on the homogeneity of solid phase distribution, and the appropriate blade structure can make the particles have a better suspension effect. Moreover, the improved blade has obvious advantages in solid–liquid space homogenization in comparison to the traditional blade under the same stirring conditions.