The Persistence of Vortex Structures Between Rotating Cylinders in the 10⁶ Taylor Number Range

The flow in the annular gap d = R_o-R_i between a stationary outer cylinder of radius Ro and a co-axial rotating inner cylinder of radius Ri is characterised at large gap, over the radius ratio (η) range 0.44 ≤ η ≤ 0.53 and aspect ratio (Γ) range 7.81 ≤ Γ ≤ 11.36. These configurations are more representative of turbomachinery bearing chambers and large rotating machinery than the journal bearing geometries of narrow gap commonly reported in the literature. Particle Image Velocimetry measurements are taken across the full meridional plane over the Taylor number (Ta) range 258 × 103 ≤ Ta ≤ 10.93 × 10⁶, which is 1000 times higher than the critical Taylor number for the onset of the first axisymmetric Taylor instability. Well-defined azimuthal vortex structures persist over this high Taylor number range, characterised by a constant number of vortices at a given aspect ratio, vortex core axial and radial motion over time, and mixing between neighbour vortices. This regime, with wavy Taylor vortex flow like features, is defined over the range 1.18 × 10⁶ ≤ Ta ≤ 6.47 × 10⁶. These results form a body of experimental evidence from which further progress in the understanding of the wavy Taylor vortex dynamics can be sought, through advanced flow dynamic models that reproduce the persistence of the observed flow features.