M. P. Escudier
Brown, Boveri & Cie., Baden, Switzerland

This figure shows changes in vortex structure with increasing ? R ²/ v for H/R=1.75 (upper row) and 2.5 (lower row). (By permission of Springer-Verlag, New York).

Figure 1

We produced the flow in a closed cylindrical container completely full of a glycerine water mixture by rotating one endwall. We made a diametral plane visible by using laser-induced fluorescence. The two sequences of photographs above show the structure of the central core of the flow (30% of the total diameter). For a given value of the height-to-radius H/R (> 1.2), there are upper and lower limits to the rotation Reynolds number ? R ²/ v between which one, two, or three vortex breakdown bubbles occur on the axis of symmetry. For ? R ²/ v>2500 the flow becomes increasingly oscillatory and eventually turbulent. A complete description of the experiment has been given elsewhere. ^[1]