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Chamber Dimension Effects on Induced Flow and Frictional Resistance of Enclosed Rotating Disks
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1960
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Frictional ResistanceUnsteady FlowEngineeringFlow ControlChamber Dimension EffectsAerospace EngineeringMechanicsFluid MechanicsMechanical EngineeringInduced FlowFlow PhysicTurbulent Flow Heat TransferSmooth Plane DiskAerodynamicsFundamental Fluid MechanicsBoundary LayerTorque Data
Fluid mechanics of a smooth plane disk rotating inside a right‑cylindrical chamber have been studied experimentally and theoretically. The study seeks to acquire systematic torque, velocity, and pressure data across Reynolds numbers 10³–10⁷ and axial clearance ratios 0.0127–0.217, and to develop and validate an approximate theory for axial‑clearance effects in separate boundary layers. Measurements of torque, velocity, and pressure were performed over the specified ranges, and an approximate theoretical model for separate boundary layers was developed and compared with the data. Four distinct flow regimes in the axial gap were identified and mapped to Reynolds number–axial spacing combinations; the theory accurately predicts axial‑clearance effects, but velocity and pressure data show that core‑rotation concepts must be revised due to secondary flows and skewed boundary layers.
The fundamental fluid mechanics associated with the rotation of a smooth plane disk enclosed within a right-cylindrical chamber have been studied both experimentally and theoretically. In order to acquire further and systematic information pertinent to this problem, which has received much attention in the past, torque data were obtained over a range of disk Reynolds numbers from 103 to 107 for axial clearance-disk radius ratios s/a from 0.0127 to 0.217 for a constant small radial tip clearance and velocity and pressure data were obtained for laminar and turbulent flows. The existence of four basic flow regimes in the axial gap between the disk and casing wall was verified, and these regimes, the existence and extent of which are governed by the Reynolds number-axial spacing combinations, have been delineated. A new approximate theoretical analysis has accounted for axial-clearance effects for the case of separate boundary layers on the disk and end wall; this theory has been checked against test results. Velocity and pressure data have shown that the concept of a fluid “core” rotation in the case of separate boundary layers must be modified because of secondary flows and skewed boundary layers.