FLOW NEAR A ROTATING-DISC WITH STAGNATION FLOW

An experimental investigation of flow near a rotating disc with stagna tion flow has been carried out. Flow visualization indicates that a ci rculating how appears on the disc and fluctuates with a frequency of h alf to one sixth of that of the rotating disc. Measurements of circumf erential velocity have been made by a laser Doppler velocimeter. The r esult shows that the transition to turbulent flow occurs at a local ro tational Reynolds number of 1.5 x 10(5), and the velocity fluctuates w ith. a frequency 28-times as large as that of the rotating disc in the transitional region. The time smoothed circumferential velocity in th e laminar region is in good agreement with the theoretical value of th e free disc, irrespective of the Reynolds number of the approaching fl ow.