Transport Phenomena in Zonal Centrifuge Rotors. VII. Two-Dimensional Transient Flow Patterns and Shear Stress Distributions

Abstract

Two-dimensional transient velocity components, vr and v9, and shear stress, and rr9, distributions in Beckman B-XV size zonal centrifuge rotors were studied by the technique of birefringence using a milling yellow dye solution as an optical solution. The investigation was performed with 3, 4, 6, and 1 2 septa in a rotor with the acceleration and deceleration rates varying from ±0.4 to ±3.0 revolutions/sec2. The experiments showed that 3 or 1 2 septa configuration rotors exhibit lower shear stress distributions than the other rotor configurations, but more prominent secondary flow are occurring in these. Rotor configurations with 4 or 6 septa exhibit no secondary flow patterns, but the shear stress distributions are four to six times higher than those in 3 or 1 2 septa configuration rotors. Changing the rate of acceleration produces no noticeable effect in any flow patterns, shear stress distributions, or their magnitudes during each transient period.