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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

CFD Study of Non-Guided Laminar Mixed Convection of a High Prandtl Number Fluid in a Transformer Winding-like Geometry

Get access (open in a dialog) DOI: 10.1615/IHTC15.ees.009246
pages 2277-2288

要約

Computational fluid dynamics is used to study the unsteady laminar mixed convection of a high Prandtl number fluid around a heat-generating finite cylindrical shell oriented with its axis in the vertical direction, with axial cooling ducts both inside and outside the shell, and with radial cooling ducts interspersed at regular intervals throughout the shell. This geometry is relevant to applications in large oil-filled power transformers. The incompressible Navier-Stokes system of equations with the Boussinesq formulation of buoyancy is used to obtain temperature and flow field for typical design parameters and operating conditions. The flow field is characterized by a zigzag pattern similar to the one obtained by blocking the inner and outer cooling ducts at selected locations with fluid guides, but becomes unsteady in some cases, with the exact number of reversals of the flow direction depending strongly on the mass flow rate of the system. The average magnitude and the location of the hotspot temperature are significantly different from the fluid-guided case and the non-guided case generally shows less efficient cooling. As a consequence it requires much more effort to predict the position and level of the hotspot temperature (the key limiting design parameter) for non-guided transformer windings as compared to their guided counterparts.