Axial thrust and power consumption of propellers in viscoelastic fluids exhibiting hysteresis effect.

• The torque and thrust of propellers in viscoelastic fluids are studied. • Hysteresis effects in torque and thrust are analyzed. • Transformation of flow patterns is identified by dynamic thrust measurements. • The power consumptions of the two occurring flow patterns are similar. • The axial thrust is appropriate for distinguishing the two flow patterns. The hysteresis effect of propeller jets in viscoelastic fluids provides a new idea for improving the mixing process related to viscoelastic fluids, such as wastewater digestion. However, the application of this idea to industrial equipment requires a feasible method for flow pattern detection. This work aimed to investigate the hysteresis effect of propeller jets in viscoelastic xanthan gum solutions in terms of the torque and the axial thrust. The axial thrust and the torque were measured using a rheometer equipped with a marine propeller. Both the averaged and the dynamic results were analyzed. The axial thrust was found to be appropriate to distinguish the semi-radial and the axial patterns in the hysteresis range. The difference in torque between the two flow patterns at the same rotational speed in the hysteresis range is insignificant. [ABSTRACT FROM AUTHOR]