An investigation of swirling flow in a cylindrical tube

An experimental study was performed for measuring velocity and turbulence intensity in a circular tube for Re=10,000, 15,000 and 20,000, with swirl and without swirling flow. The velocity fields were measured using PIV techniques and swirl motion was produced by a tangential inlet condition. Some preliminary measurements indicated that over the first 4 diameter, two regions of flow reversal were set up ( the so called 2-cell structure). At the highest Reynolds numbers., the maximum values of the measured axial velocity components had moved toward the test tube wall and produce more flow reversal at the conter of the tube. As the Reynolds number increased, the turbulence intensity of swirling flow at the tube inlet also increased.