Study of a turbulent natural convection in cylindrical annuli of gas-insulated transmission lines 400 kV

This paper presents a numerical study of the natural convection of gases (mixture of SF6 and N2) in a horizontal annulus. It consists of thermal analysis of high voltage power gas insulated transmission lines. In different case studies the inner cylinder is heated up of a constant heat or kept at a constant temperature, the outer cylinder is maintained at constant temperature. The cylinders are long and the flow is assumed to have axially independent properties. The two-dimensional analyses of the heat transfer and fluid motion are performed for Rayleigh number ranging from 105 to 1010, the radius ratio is at 2.5. Comparisons are made with experimental test set up and measurements.