On the Oscillatory Phenomena in a Swirling Pipe Flow : 1st Rep. Experiments on the Precession of the Vortex

Abstract

This study reports on an oscillatory phenomenon of the vortex in a cyclone separator shaped vessel. In the vessel the primary flow field is such that the axial flow reverses and the average flow rate is zero in any section of the vessel. Under some conditions the vortex turns and attaches itself to the cylindrical wall of the vessel instead of being attached to the center of the end plate. The point of attachment rotates in a horizontal plane, and periodic fluctuations are produced in the flow. The unique behaviour of the vortex mentioned above is examined by detailed experiments. It is found that the configuration of the precessing vortex core is almost a plane curve, and that the frequency of the precession depends directly on the local strength of the primary swirling flow near the attachment position. A simple mathematical model is proposed to explain the qualitative properties of the phenomenon.