Visualization of the flow structure in a vortex tube

The temperature separation in a vortex tube has been investigated for the purpose of exploring the phenomenon and improving the tube performance. Different explanations for the temperature separation have been proposed. However, there has not been a consensus in the hypothesis.This paper reports on a study in progress exploring the flow structure in a vortex tube. Flow visualization, using water as a working fluid, is used to reveal the existence of multiple circulation regions within the vortex tube and a new hypothesis describes the temperature separation mechanism. This research contributes to the understanding of the flow behavior in a vortex tube and supports the previous works that show the generation of the cold component of the flow is the result of the expansion near the cold nozzle and the hot component is produced due to the friction between the layers of flow.

► Water is used to visualise the flow structure in a vortex tube.
► Velocity distributions are conducted.
► Multi-circulation is first identified.