Study on cavern evolution and performance of three mixers in agitation of yield-pseudoplasitc fluids

The hydrodynamic performance of the three mixers (single shaft central mixer, single shaft off-centred mixer, dual shaft off-centred mixer, i.e. SSC, SSO, DSO), was investigated in the mixing of yield-pseudoplastic fluids (xanthan gum solutions) in the laminar regime. Computational Fluid Dynamics was employed to simulation the apparent viscosity distribution, mixing time and the flow pattern in the stirred tank. The influence mechanism of the rotational speed and fluid rheology on the cavern evolution was explored deeply. The results verified that the faster the rotating speed, the greater influence of the fluid rheology was obtained on the cavern evolution. Moreover, the Nt95 of DSO was nearly 42.8% and 6.1% shorter than that of SSC and SSO at the same Re*, respectively. These data also revealed that the DSO was more efficient than SSC and SSO in mixing of yield pseudoplastic fluids with regard to the mixing time and power drawn.