Abstract of

STEADY AND TRANSIENT TOPOLOGIES OF CONFINED VORTEX BREAKDOWN GENERATED BY A ROTATING CONE J.C.F. Pereira and J.M.M. Sousa Mechanical Engng. Dept., Instituto Superior Tecnico .

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Steady and transient structures in confined swirling flow generated by a rotating cone within a closed cylindrical vessel are presented and discussed, based on flow visualisation. The results are supplemented by detailed laser-Doppler velocity measurements of a flow regime displaying double vortex breakdown. The topology of the steady vortex breakdown structures is unveiled.  These consist of closed, toroidal, axisymmetric bubbles. Sudden variations of the Reynolds number imposed to the swirling flow are observed to produce transient responses of different character, depending upon the sign of the variation. However, in all cases, the axisymmetry of the flow structures is seen to be preserved during the complete process.

 

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