Real-time numerical analysis on insulation capability improvement of compact gas circuit breaker

In order to avoid a ground fault during a large current interruption, the effect of roughness pattern inside the exhaust tube on the rapid cooling of high temperature SF₆ exhaust gas has been clarified in detail. In this study, large-eddy simulation of compressible turbulent flow under the realistic inlet conditions related to the available experimental data has been carried out. It is shown that introducing roughness pattern on the inner wall of exhaust tube is very effective for the improvement of insulation capability due to the enhanced active mixing and the flowing in of cold ambient gas from the tube exit. Finally, the computed temperature on the inner wall of exhaust tube shows a good qualitative agreement with the experimental data especially for the rough surface just after the applied transient recovery voltage.