Measurement of velocity distribution in the Brabender Farinograph as a model mixer, using Laser-Doppler Anemometry

Abstract

The nonintrusive technique of Laser-Doppler Anemometry was used to characterize flow velocity distribution in the Brabender Farinograph, which is often used to mix rheologically diverse food materials. A two-dimensional Argon-ion laser Doppler system was used to obtain local velocity data at selected locations in this complex mixer. Three components of velocity were obtained as a function of time and spatial location for model fluids with characteristic rheological properties. The results revealed that the velocity distribution in the Farinograph changes with the time-relative motion of the blades and with fluid rheology. Velocity values at locations close to the blades were much higher for the non-Newtonian fluids than for the Newtonian fluid studied. The prevalence of static zones at regions away from the blades was noticeable, particularly in the non-Newtonian fluids. These findings indicate that Laser Doppler Anemometry is a valuable tool in the design and analysis of complex mixing processes.