Analysis on the gas flow characteristic of high voltage SF6 circuit breaker with novel energy separated nozzle

Abstract

In this paper, the high voltage SF6 circuit breaker (HV SF6CB) was taken as the research object, an axial vortex arc quenching chamber structure with a novel “X-type” guide blade on the nozzle upstream is presented to effectively control the kinetic energy of the free vortex formed by the gas flow and to exchange the energy in the radial direction. During the interruption, the temperature gradient along the radial direction can be generated. In the process of the internal energy exchange, because the outer spin flow of the turbulence gains more kinetic energy than the internal energy loss, which makes the total temperature of the outer rotary flow increase, and the internal gas flow temperature decrease accordingly. In this paper, the novel nozzle is proposed and applied to achieve energy separated vortex movement of the high pressure gas flow to reduce the axial temperature and increase the gas flow capability. And a 550kV SF6 CB was taken as the research object in this paper. By using finite volume method (FVM), the 3D flow field mathematical model under the small capacitive current interruption is proposed and the influence of the X type guide blade structure on flow field is simulated. By solving the gas flow field with complex flow path, supersonic nozzle, viscous, compressible and variable boundaries, the influences of different axial vortex nozzle structure on the velocity and pressure distributions have been achieved. In addition, the comparisons of gas flow distributions in the chamber with and without X type guide blade nozzle were obtained and analyzed.