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

2015

IREASE

Self Cite

This study investigates by Particle Image Velocimetry (PIV) the wavy Taylor vortex flow that develops in the gap between concentric rotating cylinders of low aspect ratio and low radius ratio, which is a configuration relevant to oil bearing chambers in turbomachinery. The configuration is characterised by a larger annular gap width than the one typically used in journal bearings and by a Taylor number ( ) of 2.47 x 10 6 , which is 1000 times higher than the first critical Taylor number. It is found that the non-uniform axial spacing of the vortex cores induces an asymmetric radial velocity profile and an inflected axial velocity profile close to the cylindrical walls. The outflow at the centre of each pair of Taylor vortices that make up a vortex cell is strong and it is characterised by a sharp radial velocity peak. The inflow between pairs of Taylor vortex cells is unconventional in that it is characterised by pairs of confluent streams from the outer cylinder that merge towards the inner cylinder. These results form a body of experimental evidence on the flow features that may occur in engineering practice in oil bearing chamber flows, with relevance to lubrication and wear.

Section: Experimental Facility and Experimental Proceduresmentioning

confidence: 69%

Section: Characteristics Of the Flow Regimementioning

confidence: 93%

Section: Experimental Facility and Experimental Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

PIV Study of the Flow Across the Meridional Plane of Rotating Cylinders with Wide Gap

2015

IREASE

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Numerical Investigation of the Three-Dimensional Pressure Distribution in Taylor Couette Flow

Journal of Fluids Engineering

2017

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An investigation is conducted on the flow in a moderately wide gap between an inner rotating shaft and an outer coaxial fixed tube, with stationary end-walls, by three-dimensional Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD), using the realizable k−ε model. This approach provides three-dimensional spatial distributions of static and dynamic pressures that are not directly measurable in experiment by conventional nonintrusive optics-based techniques. The nonuniform pressure main features on the axial and meridional planes appear to be driven by the radial momentum equilibrium of the flow, which is characterized by axisymmetric Taylor vortices over the Taylor number range 2.35×106≤Ta≤6.47×106. Regularly spaced static and dynamic pressure maxima on the stationary cylinder wall follow the axial stacking of the Taylor vortices and line up with the vortex-induced radial outflow documented in previous work. This new detailed understanding has potential for application to the design of a vertical turbine pump head. Aligning the location where the gauge static pressure (GSP) maximum occurs with the central axis of the delivery pipe could improve the head delivery, the pump mechanical efficiency, the system operation, and control costs.

The Three-Dimensional Velocity Distribution of Wide Gap Taylor-Couette Flow Modelled by CFD

International Journal of Rotating Machinery

2016

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A numerical investigation is conducted for the flow between two concentric cylinders with a wide gap, relevant to bearing chamber applications. This wide gap configuration has received comparatively less attention than narrow gap journal bearing type geometries. The flow in the gap between an inner rotating cylinder and an outer stationary cylinder has been modelled as an incompressible flow using an implicit finite volume RANS scheme with the realisablek-εmodel. The model flow is above the critical Taylor number at which axisymmetric counterrotating Taylor vortices are formed. The tangential velocity profiles at all axial locations are different from typical journal bearing applications, where the velocity profiles are quasilinear. The predicted results led to two significant findings of impact in rotating machinery operations. Firstly, the axial variation of the tangential velocity gradient induces an axially varying shear stress, resulting in local bands of enhanced work input to the working fluid. This is likely to cause unwanted heat transfer on the surface in high torque turbomachinery applications. Secondly, the radial inflow at the axial end-wall boundaries is likely to promote the transport of debris to the junction between the end-collar and the rotating cylinder, causing the build-up of fouling in the seal.