Experiments on the flow processes in simple rotating channels

Abstract

In a previous series of tests, the character and distribution of flow in the channels of a largescale model of a centrifugal compressor impeller were explored and measured. In order to make a more detailed study of the flow that was thus discovered, a new series of tests was carried out and is described in the present report. The complete rotor was replaced by simplified models of single channels, in which the flow could be compared while the channel was stationary, or rotating. These two-dimensional channels were given a range of divergence angles, and the flow compared with that in stationary diffusers. It was shown that rotation tended to stabilize the flow pattern, with breakaway from the wall occurring on the suction side of the rotating channel, and a jet of high-speed flow issuing from the pressure side of the channel. Channel-exit speed and stability profiles are presented covering ranges of channel divergence angles, and Reynolds and Rotation Numbers. Smoke visualization pictures enable the flow within and downstream of the channel to be seen, and show the location of the flow detachment point on the suction wall.