Flow structure between two co-axial disks rotating independently

Abstract The present experimental work is the first systematic study on the qualitative nature of three-dimensional flow structure between two rotating co-axial disks at a relatively wide range of rotational conditions. The experimental facility designed for this work is of two sets of power section that can be controlled independently to drive two co-axial disks. Smoke (paraffin mist) is employed as the tracer for visualizing the present three-dimensional swirling flows. Three different modes of disk rotation, i.e. co-rotation, rotor–stator, and counter-rotation, are considered. Theory of rotating fluids with the presence of centrifugal and Coriolis forces stemming from the disk rotation are employed to manifest the flow mechanisms at various rotational conditions. Effects of the shroud on disk rim and the gap size between two disks on the development of the flow structure are explored. The major governing parameters of the present flow configuration are the rotational Reynolds number ( Re Ω ≡ΩR 0 2 /ν ), the rotating rate-ratio of two disks ( Γ≡Ω 2 /Ω 1 ), and the gap-ratio G ≡ S / R 0 with the ranges of 4.7×10 3 ⩽Re Ω ⩽14.1×10 4 , −1.2⩽ Γ ⩽1.2, and 0.08⩽ G ⩽0.133. The present observations reveal distinct flow structure between two disks rotating at various conditions and provide profound insights for better understanding of fundamental mechanisms of the complex three-dimensional rotating flows that are valuable in analysis and design of rotating flow systems.

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