Measurements of Continuous Phase Velocities in Solid–Liquid Flow at Elevated Concentrations in a Stirred Vessel Using LDV

Laser Doppler velocimetry was used to evaluate liquid axial velocities and turbulence levels in a stirred vessel equipped with a standard 45 pitch blade turbine. The measurements were conducted utilizing the method of matching refractive indices. Three different solid particle sizes were studied; 1.0 mm, 1.5 mm and 2.0 mm, and the maximum mean volume fractions for which measurements could be performed were 6%, 9% and 9%, respectively. The axial velocities were found to decrease with increasing solid content while the liquid r.m.s. velocities were higher in the suspensions than in a single phase flow, an effect that increases with increasing particle size.