During the breaking process of the DC air circuit breaker used in rail transit

the arc root of air arc may stick at the edge of the arc path

which produces the phenomenon of metal droplet splashing and affects the breaking. In this paper

the influence of volume force exerted by metal droplet on the flow field of DC air arc is considered

and the traditional magnetohydrodynamics(MHD) equation is improved; moreover

a bidirectional coupling model of metal droplet and air arc is established

and the metal droplet produced by splashing is tracked. The changes of temperature field and flow field during the breaking of air arc under the influence of liquid droplet are calculated

and the vortex phenomenon affecting the arc root movement is analyzed. The results show that the metal droplet splashing can change the air arc flow field distribution

prolong the arc root sticking time

and increase the arc column temperature

arc current

arc burning time and breaking difficulty. This study provides a theoretical basis for reducing the effect of metal droplet on DC air arc breaking.