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ISSN Online: 2377-424X

ISBN Print: 0-89116-559-2

International Heat Transfer Conference 8
August, 17-22, 1986, San Francisco, USA

NUMERICAL STUDIES OF MIXED CONVECTION FLOWS IN THE ANNULUS BETWEEN VERTICAL CONCENTRIC CYLINDERS WITH ROTATING INNER CYLINDER

Get access (open in a dialog) DOI: 10.1615/IHTC8.3620
pages 435-440

Résumé

A numerical study has been conducted to determine the heat transfer characteristics and flow patterns which develop around- a rotating, heated vertical cylinder enclosed within a stationary concentric cylinder. A tall annulus (aspect ratio of 10) with fixed, adiabatic horizontal endplates and a radius ratio of 2 has been considered. Solutions reveal that two instabilities exist for this geometry, one being purely hydrodynamic and the other thermal in origin. The hydrodynamic instability manifests itself by the appearance of the toroidal Taylor vortices, while the thermal instability is characterized by the sudden onset of a multicellular flow pattern. This paper investigates the mutual interaction of both modes of instability and the resultant effects on the flow patterns and heat transfer rates. A wide range of parameters is studied (0 ≤ Re ≤ 103; 0 ≤ Gr ≤ 105) for the air-filled gap (Pr = 0.7). Heat transfer rates are presented as a function of the rotational parameter σ = Gr/Re2. This parameter is a densiometric Froude number, and gives the relative importance of the buoyancy and rotational effects. Solutions are obtained by solving the time-dependent Navier-Stokes and energy equations, cast in the stream function -vorticity - swirl velocity form.