Optimization of the Nozzle Structure in a 252kV Arc Extinguishing Chamber via Airflow Field Simulation

This study focuses on optimizing the nozzle structure of arc extinguishing chamber in a 252 kV circuit breaker based on airflow field simulations. The subject of this optimization is an arc-extinguishing chamber structure without an auxiliary nozzle of PTFE. Using fluid dynamics software, an arc model of the chamber is established to investigate the pressure variation patterns inside the compression chamber and the airflow velocity characteristics at the nozzle throat. The downstream nozzle structure is optimized considering the dynamic characteristics of the operating mechanism. Through comparative analysis of the interruption process under 30 kA current with different nozzle parameters, it is found that as the inclination angle of the large nozzle downstream increases, both the arc temperature and gas flow velocity gradually decrease during the arcing period. A smaller nozzle inclination angle facilitates arc extinction but requires higher erosion resistance. Ultimately, a structure with a 6° inclination angle is selected as the optimized nozzle configuration.