An investigation on vortex breakdown phenomena in avertical cylindrical tube

الملخص EN

Vortex flows are subject to a number of major structural changes involving very large disturbances when a characteristic ratio of azimuthal to axial velocity components is varied.

Vortex breakdowns are among the structural forms that may occur.

This phenomenon is one of the hydrodynamic instability problems and it is encountered in many practical application, such as, aerodynamics (in aeronautics), combustion chamber, diffusers and nozzle.

The objectives of the present research are to investigate the effect of Reynolds number (Re) and circulation number (Ω) on the observed modes of the vortex breakdown.

The position of the vortex breakdown with two vertical cylinder tube length as well as for clockwise and anti-clockwise flow direction is also investigated.

The results revealed that there are a total of six distinct modes of the disruption of the vortex core as Re and Ω of the flow were varied.

The breakdown position was found to be dependent on both Re and Ω of the flow.

Whereas, for all Re values an increase in Ω always results in moving the breakdown position upstream for all Re values.

The breakdown position is smaller for anti-clockwise flow direction than that, when vanes were set at clockwise flow direction for long and short tube.