Transient Response Simulation of Downstream Thermofluid Field in a Gas Circuit Breaker during Current Interruption

Abstract

A transient response of SF 6 thermofluid field inside the exhaust tube in a Gas Circuit Breaker under high temperature, high pressure and high velocity conditions is analyzed by taking compressible effect and some realistic processes into account related to the available experimental data of GCB test facility. Furthermore, computational simulation is conducted to clarify the effective cooling process of SF 6 hot gas flow inside the exhaust tube for transient time to avoid the SF 6 hot gas breakdown near exhaust tube exit after the arc current interruption. It is found that the SF 6 hot gas flow can be effectively cooled down for the rough inside wall of exhaust tube due to the separation of SF 6 hot gas flow from the inside wall and also active mixing with upstream cold gas. The effect of roughness pattern on the real time thermofluid field of SF 6 hot gas flow and possible breakdown region are also clarified. Finally, the computed temperature in GCB shows the good agreement with the available experimental data for smooth surface of exhaust tube.

Real-Time Numerical Analysis on Insulation Capability Improvement of Compact Gas Circuit Breaker

“…As one of the method for the rapid cooling in exhaust tube, passive cooling by introducing roughness inside the inner surface of exhaust tube has been proposed [5]. Recently, it has been verified by the simplified model that this passive cooling by rough surface is effective for the rapid cooling of high temperature exhaust gas and also for the improvement of insulation capability [5].…”

“…Recently, it has been verified by the simplified model that this passive cooling by rough surface is effective for the rapid cooling of high temperature exhaust gas and also for the improvement of insulation capability [5]. In this simplified model, exhaust gas flow is assumed to be laminar and the real nozzle configuration is not included in the computational domain.…”