Numerical calculation of turbulent natural convection in a cylindrical transformer enclosure

Abstract

Numerical calculations of turbulent natural convection in the enclosure of the 20 kVA oil-immersed transformer model are presented. The transformer is modeled as two concentric cylinders with different heights and diameters. The correlating equation between the mean Nusselt number and the Rayleigh number can be obtained for Ra = 10 8 to 10 9 . The thermal boundary layers are well represented in the temperature distributions along the wall of the transformer model. The flow stratification between the hot and cold walls cannot be seen in the transformer model. The turbulence eddy viscosity has its maximum at the center of the core and its maximum values at the top of the core are slightly larger than those at the bottom of the core.