Modifications in impeller blades for high efficiency mixing of pseudoplastic fluid in a stirred tank

Abstract

Self-similarity impeller (SS impeller) was applied to enlarge the cavern region for the mixing of pseudoplastic fluid. The mixing characteristics of pseudoplastic fluid in an SS impeller stirred tank were explored by employing experimental and numerical simulation. The results indicated that the utilization of SS impeller resulted in significant improvement in the largest Lyapunov exponent of mixing system, as well as reduced mixing time and decreased mixing efficiency number compared with pitched-blade impeller (PB impeller) operating at an equivalent power consumption per unit volume. A reduction in power consumption was obtained through the application of self-similar configuration for the impeller blades. Meanwhile, SS impeller could enhance the fluidity of pseudoplastic fluid, minimize the stagnation regions, and enlarge the cavern region. This phenomenon was even more pronounced as the increase in self-similar iteration number of SS impeller. It was found that the design of self-similar structure for impeller blades could expand the cavern region and enhance the mixing efficiency for the mixing of pseudoplastic fluid, particularly as the self-similar iteration number increased.