662 / 2017-05-22 21:47:53

The influence of energy separated nozzle on the gas flow parameters for SF6 circuit breaker

Energy Separation,SF6 Circuit Breaker,Arc Quenching Chamber,Nozzle,Vortex Flow

As the leading product of HV switches, SF6 CB plays an important control and protection role in high voltage (HV), extra high voltage (EHV) and ultra high voltage (UHV) transmission systems. The flow path of SF6 gas during the breaking process from the pressure cylinder to the nozzle downstream is very complex, and its dynamic behavior presents unsteady and non-linear characteristics. In order to improve the dielectric recovery and breaking capability without reducing the insulation capability of the arc quenching system, a new nozzle structure with vortex flow energy separation is proposed in this dissertation by setting the (“X-type”) guide blade at the upstream of the nozzle to control the gas flow path and form turbulent vortex stream at the opening contacts, that is, the axial vortex movement. The kinetic energy of the formed vortex exchanges in the radial direction during the moving process, which thus causes the temperature gradient change along the radial direction. During the internal friction process, the outer spin gas flow gains more kinetic energy than its internal energy loss, hence, the outer rotary flow temperature will increase. In contrast, the temperature of the internal gas flow decreases due to the loss of most kinetic energy. Consequently, the physical and mathematic model for 3D flow field is established and the finite volume method is employed to conduct numerical simulation for flow field domain. Under the circumstance that the gas flow in arc quenching chamber does not change, this dissertation studies the parameter characteristics of 3D flow field in the arc quenching chamber in the structure with or without guide blade during the interruption process of the small capacity current so as to find out the distributions of pressure, velocity, Mach number and temperature.