Ekman Layer Scrubbing and Shroud Heat Transfer in Centrifugal Buoyancy-Driven Convection

Gao, Feng and Chew, John (2020) Ekman Layer Scrubbing and Shroud Heat Transfer in Centrifugal Buoyancy-Driven Convection In: ASME Turbomachinery Technical Conference & Exposition (Turbo Expo 2020), 22-26 Jun 2020, ExCeL London Convention Center in London, United Kingdom.

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Abstract

This paper presents large-eddy and direct numerical simulations of buoyancy-driven convection in sealed and open rapidly rotating cavities for Rayleigh numbers in the range 10⁷–10⁹, and axial throughflow Reynolds numbers 2000 and 5600. Viscous heating due to the Ekman layer scrubbing effect, which has previously been found responsible for the difference in sealed cavity shroud Nusselt number predictions between a compressible N-S solver and an incompressible counterpart using the Boussinesq approximation, is discussed and scaled up to engine conditions. For the open cavity with an axial throughflow, laminar Ekman layer behaviour of the mean flow statistics is confirmed up to the highest condition in this paper. The Buoyancy number Bo is found useful to indicate the influence of an axial throughflow. For the conditions studied the mean velocities are subject to Ra, while the velocity fluctuations are affected by Bo. A correlation, Nu' = 0.169(Ra')^0.318, obtained with both the sealed and open cavity shroud heat transfer solutions, agrees with that for free gravitational convection between horizontal plates within 16% for the range of Ra' considered.

Item Type:	Conference or Workshop Item (Conference Paper)
Divisions :	Faculty of Engineering and Physical Sciences > Mechanical Engineering Sciences
Authors :	Name Email ORCID Gao, Feng f.gao@surrey.ac.uk Chew, John J.Chew@surrey.ac.uk
Date :	22 September 2020
Funders :	Engineering and Physical Sciences Research Council (EPSRC), Rolls-Royce plc
Copyright Disclaimer :	Copyright © 2020 by ASME
Related URLs :	Organisation
Additional Information :	Paper no. GT2020-16220. (Originally scheduled for 22-26 June in London, this conference was actually rescheduled as a 'virtual' online conference on 21-25 September.)
Depositing User :	Clive Harris
Date Deposited :	05 Jun 2020 13:46
Last Modified :	22 Sep 2020 02:08
URI:	http://epubs.surrey.ac.uk/id/eprint/857092

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