| The general objective of this PhD study is to develop models that simulate the snow melting process on overhead conductors and predict snow shedding under various meteorological and current transmission conditions. In an attempt to validate this new model, a number of experimental tests were carried out in the CIGELE cooling chamber and wind tunnel, and the results obtained from these tests were then compared with those from numerical simulations.;Secondly, a microstructure model was developed to estimate the equivalent thermal conductivity of dry snow. This study describes the relationship between the equivalent thermal conductivity and the microstructure of dry snow under different temperatures regimes. These results were compared with those obtained in prior research, and showed good agreement. A set of experiments was carried out at the CIGELE laboratories and the results were compared with those produced by this particular model. Furthermore, the relationship between the snow conductivity model and the weather is introduced here.;Thirdly, a two-dimensional time-dependent numerical model of water percolation within a wet snow sleeve was constructed based on the Galerkin method. The effects of wind speed, air temperature, Joule heating, snow surface roughness and snow grain size was investigated. The numerical results show that Joule heating and snow surface roughness have an obvious influence on water percolation. The time required to reach quasi-steady state was reduced by 50% and more, considering that the electric current or surface roughness exceeded a critical value. The numerical results accord well with the experimental studies conducted at the CIGELE laboratories.;Fourthly, the problem of determining the occurrence of snow shedding was also investigated. Such an analytical model is based on a dry snow failure model and on experimental tests carried out at the CIGELE laboratories. It is a model which takes into account the effect of the water flow within the sleeve. The results show that the time required to snow shedding occurrence decreases in a non-linear fashion as the initial volume water content, the air velocity, and the electric current intensity increase. This model can provide a rapid estimation of the required Joule heat or wind to trigger snow shedding from the cable.;Firstly, two-dimensional Reynolds-Average Navier-Stokes (RANS) simulations were implemented in FLUENT software to predict both the local heat-transfer coefficient distribution along the snow sleeve surface in a cross flow of air, and the overall heat-transfer rate. These investigations reveal the characteristics of forced convection around a snow sleeve, especially the effects resulting from the roughness of the snow surface and the non-circular shape of the sleeve. The study shows that roughness has a significant effect on the heat transfer rate, although the effect of the non-circular shape is negligible in most cases. The computational results show a satisfactory concordance with the theoretical analyses as well as with the experimental data derived from the literature in the field. |
