Experimental and Numerical Investigation of the Characteristics of Novel Disc Turbines in Aerated Stirred Tanks

Abstract

In this work, the gas dispersion and transport characteristics of three different disc turbines, namely, parabolic disc turbine (PDT), novel swept-back parabolic disc turbine (SPDT), and staggered fan-shaped parabolic disc turbine (SFPDT), are characterized by experiments and two-fluid model/RANS simulations. The physical explanation of the superior power characteristics of SFPDT and SPDT is elaborated using the pressure distribution and drag force coefficient on a blade surface. Gas–liquid performance parameters such as critical dispersion speed, relative power demand (RPD), and volumetric mass transfer coefficient are assessed under different conditions. The results show that SFPDT and SPDT can produce smaller flow separation regions and trailing vortices, resulting in smaller gas cavities under aeration conditions. SFPDT has the lowest critical dispersion speed under a high flow rate, while SPDT consumes the least power. Both SFPDT and SPDT exert roughly 7% higher gassed power input than PDT under aeration conditions and have higher efficiency on gas–liquid mass transfer than PDT. Moreover, empirical correlations from experimental data for SFPDT and SPDT are presented to provide a reference to the design of industrial stirred tanks.