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OSCILLATIONS OF HEAT TRANSFER AND LARGE-SCALE CIRCULATION IN TURBULENT MIXED CONVECTION

Westhoff, Andreas und Schmeling, Daniel und Bosbach, Johannes und Claus, Wagner (2010) OSCILLATIONS OF HEAT TRANSFER AND LARGE-SCALE CIRCULATION IN TURBULENT MIXED CONVECTION. In: Third Int. Symposium on Bifurcations and Instabilities in Fluid Dynamics, Seite 34. The Univercity Nottingham. Third Int. Symposium on Bifurcations and instabilities in fluid dynamics, 10.-13. Aug. 2009, Nottingham (UK).

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Kurzfassung

Mixed convection (MC) describes the transport of heat in fluids when forced convection (FC) and thermal convection (TC) coexists. It is a very often occurring flow condition e.g. in the oceans, the atmosphere, indoor climatisation or in many industrial processes and applications. MC can be characterised by the dimensionless parameters Rayleigh number $Ra \equiv \Delta T \beta g H^3 / \kappa \nu$, Reynolds number $Re \equiv U H / \nu$, Prandtl number $Pr \equiv \nu / \kappa$ and Archimedes number $Ar = Ra / (Re^2 \times Pr)$ which is the ratio of buoyancy to inertia forces. In this study we investigated the influence of torsional oscilations of the large-scale circulations (LSC) on the heat transfer at MC in a rectangular cavity. To cover a large range of $600 < Re < 3 \times 10^6$ and $1 \times 10^5 < Ra < 1 \times 10^{11}$ two convection cells with an aspect ratio of 1:1:5 (height:width:length) have been constructed using air as working fluid. As a characteristic length the height $H$ of the cell is chosen and the spatially averaged inflow velocity as characteristic velocity $U$. The convection cells consist of a rectangular container with an air inlet at the top and an air outlet at the bottom. Inlet and outlet are located at the same side of the cell. They span the whole length of the cell and are constituted by rectangular channels. The bottom is equipped with a heated copper plate and the top with an aluminium heat exchanger with cooling fins. The small cell with the dimensions $H = 100$ mm, $W = 100$ mm and $L = 500$ mm was designed to be operated under high pressure conditions up to 100 bar. The large convection cell has been designed to work under ambient pressure with the same aspect ratio. However, its dimensions are scaled by a factor of 5.

Dokumentart:Konferenzbeitrag (Vortrag, Paper)
Titel:OSCILLATIONS OF HEAT TRANSFER AND LARGE-SCALE CIRCULATION IN TURBULENT MIXED CONVECTION
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Westhoff, Andreasandreas.westhoff@dlr.de
Schmeling, Danieldaniel.schmeling@dlr.de
Bosbach, Johannesjohannes.bosbach@dlr.de
Claus, Wagnerclaus.wagner@dlr.de
Datum:August 2010
Erschienen in:Third Int. Symposium on Bifurcations and Instabilities in Fluid Dynamics
Seitenbereich:Seite 34
Verlag:The Univercity Nottingham
Status:veröffentlicht
Stichwörter:mixed convection, turbulence, heat transfer, large-scale circulations, flow structure formation
Veranstaltungstitel:Third Int. Symposium on Bifurcations and instabilities in fluid dynamics
Veranstaltungsort:Nottingham (UK)
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:10.-13. Aug. 2009
Veranstalter :School of mathematical sciences University of Nottingham
HGF - Forschungsbereich:Luftfahrt, Raumfahrt und Verkehr
HGF - Programm:Luftfahrt
HGF - Programmthema:Starrflügler
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L AR - Starrflüglerforschung
DLR - Teilgebiet (Projekt, Vorhaben):L - Systeme & Kabine
Standort: Göttingen
Institute & Einrichtungen:Institut für Aerodynamik und Strömungstechnik > Fluidsysteme
Hinterlegt von: Andreas Westhoff
Hinterlegt am:26 Nov 2010 09:58
Letzte Änderung:12 Dez 2013 21:06

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