Abstract
Transition of the flow between a rotating cone and a casing is studied by using a flow visualization technique. The cone vertex angle used in the present experiment is 60°. Observations of the flow have been made for several clearance ratios s/R from 0.016 to 0.184, where s is the clearance and R is the radius of the rotating cone. Characteristics of spiral vortices which appear at first in the transition region are clarified. It is found that three different types of instabilities may occur at large clearance ratios ; one of those is a centrifugal type and the others are similar to those observed in the Ekman boundary layer. The effects of throughflow on the behavior of the spiral vortices are also investigated.
