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Numerical investigation of buoyancy-induced flow in a sealed rapidly rotating disc cavity

Gao, Feng, Pitz, Diogo B. and Chew, John W. (2019) Numerical investigation of buoyancy-induced flow in a sealed rapidly rotating disc cavity International Journal of Heat and Mass Transfer.

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Abstract

This paper presents buoyancy-induced flow for a sealed rotating cavity with rotational Rayleigh number Ra in the range 10⁷ to 10⁹. DNS for an incompressible model with the Boussinesq approximation is compared with LES for a compressible gas flow model. The compressible solver's solutions show the shroud Nusselt number scales with Ra0.286, in close agreement with the corrected experimental correlation and the Ra2/7 scaling for gravitational heat convection between horizontal plates, but differs from the N uRa1/3 scaling given by the incompressible solver. The shroud thermal boundary layer thickness, based on the root mean square of the temperature fluctuation, can be estimated with λ* = 0:5N u-1 Velocities scale approximately with Ωa√β∆T. Disc laminar Ekman layer behaviour is confirmed up to Ra = 109. An Ekman layer scrubbing effect, associated with the viscous energy dissipation, is considered to be mainly responsible for the difference in N u between the two solvers at Ra = 109, in spite of rather small Eckert number. The analysis of the turbulent kinetic energy budget shows a dominant constant buoyancy production in the core. The use of the incompressible formulation for the considered problem is restricted by the applicable range of the Boussinesq approximation characterised by the buoyancy parameter β∆T and neglect of viscous heating and compressibility effects characterised by the Eckert number Ec = Ω2r2m =(Cp∆T).

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Mechanical Engineering Sciences
Authors :
NameEmailORCID
Gao, Fengf.gao@surrey.ac.uk
Pitz, Diogo B.
Chew, John W.J.Chew@surrey.ac.uk
Date : 2019
Funders : Engineering and Physical Sciences Research Council (EPSRC)
Copyright Disclaimer : © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Related URLs :
Depositing User : Clive Harris
Date Deposited : 29 Oct 2019 12:05
Last Modified : 29 Oct 2019 12:08
URI: http://epubs.surrey.ac.uk/id/eprint/852974

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