Modelling of the mixed convection in the windings of a disc-type power transformer

The present article describes flow pattern of cooling oil inside the windings of a disc-type transformer. The geometrical model is established as an array of rectangular blocks arranged in-line and dissipating heat. The attention of the investigation is essentially focused on the parameters supposed to influence the how pattern in order to get a one-dimensional correlation for the heat transfer. Since the convection is mixed, the parameter Re/Gr(1/2) is used to characterise the flow. It has the range (0.1, ..., 1). The ranges of the other parameters are: 15 < Re < 120, 66 < Pr < 85. It has been observed that mass flow fluctuation occurs in vertical channels due to some flow through horizontal channels. This fluctuation is proved to be influenced by the above-mentioned parameters. (C) 2000 Elsevier Science Ltd. All rights reserved.