Analysis and application of grid size influence in air flow field simulation of high voltage circuit breaker

In the research and development of high voltage circuit breaker, one method is to simulate the breaking arc of circuit breaker, taking the current curve and travel curve loaded in the high current breaking test as the input condition to simulate the arc starting, burning arc and arc quenching process in the breaking process of circuit breaker. However, for the same circuit breaker, the same test conditions, different grid sizes will affect the simulation results, including arc voltage, expansion chamber pressure, nozzle upstream pressure, nozzle throat pressure and other key breaking parameters. To study the effect of different grid sizes on the open arc simulation. Based on the existing mathematical model of circuit breaker breaking process, we control the grid size modification method, use the same geometric model, input the same boundary conditions, compare the simulation results, and provide a more accurate grid division standard for the subsequent development of circuit breaker breaking arc simulation method. By setting the arc area axial grid to 0. 25mm and 0. 5mm, the arc area radial grid to 0. 0667mm and 0.1mm, 0. 5mm, 1mm and 2mm, simulation calculation under the same working conditions, extracting the arc voltage, expansion chamber pressure, nozzle upstream pressure for comparison, it is found that the calculation results of the arc area radial grid from 0.1mm to 0. 0667mm, while the arc area axial grid from 0. 5mm to 0.5 mm to 0. 25mm. For the expansion chamber grid, the grid size setting of 0. 5mm is more stable than the calculation result of 1mm and 2mm. Therefore, in the subsequent open arc simulation, it is recommended to set the radial grid of the arc area to 0. 0667mm, the axial grid to 0. 5mm, and the expansion chamber grid to 0. 5mm. According to the simulation results, we can guide the development and design of high voltage circuit breaker.