Influence of the vortex angle on the efficiency of the Ranque-Hilsch vortex

Abstract

The phenomenon of temperature distribution in confined steady rotating gas flows is called Ranque-Hilsch effect. The simple counter-flow vortex tube consists of a long hollow cylinder with tangential nozzle at one end for injecting compressed air. Rotating air escapes the tube through two different outlets: a central orifice diaphragm placed near the inlet where the cold portion of air escapes from and a ring–shaped peripheral outlet at the opposite end of the tube where the hot air leaves the tube. This paper focuses on the performance of the Ranque–Hilsch vortex tube. The flow inside the vortex tube can be described as rotating air, which moves as a spring-shaped vortex track. The peripheral flow moves toward the hot end and the axial flow moves in the opposite direction toward the cold end. The angle between the circular helix and the vertical axis is an important parameter, since it decides the length of the vortex track and peripheral velocity of the flow, which influence the efficiency of the vortex tube. The angle can be called “Ranque angle” or “vortex angle”. Various structures were placed in the vortex chamber of a specially designed tube to generate different vortex angles. A series of experiments have been done in order to find the relationship between the vortex angle and the performance of the vortex tube.