An LDA study of the radial discharge velocities generated by a Rushton turbine : Newtonian fluids, Re ≥ 5

Abstract

LDA studies are reported on the radial discharge flows from a Rushton turbine impeller. Mean and r.m.s. centre line and outled velocity profiles were obtained and, from the latter, flow numbers (F1) were calculated. In addition, impeller power numbers (Po) have been measured. Transparent Newtonian fluids of viscosity to 1000 mPas were using giving Reynolds number (Re) from 5≤Re≤∼5×10 4 . For Re>∼500, the results were similar to those reported in the literature for measurements made in water (Re>∼10 4 ) with F1≃0.78. For Re<∼500, the mean and r.m.s. values fell as well as F1 and for Re<∼20, F1∞Re whilst Po∞Re -1 . The results help the understanding of the effect of viscosity on flow in a stirred vessel and provide a good baseline for comparative studies of such flows in viscous non-Newtonian fluids