Regarding the insulation performance degradation of the epoxy insulators on roof of high-speed trains due to surface discharge

a fluid model and a three-dimensional nonlinear transient electric-thermal coupling model of roof insulator for pantograph are established with the software Ansys to analyze the airflow and pressure distributions around the insulator

the variation of trace depth with airflow velocity and pressure in circumferential direction and along the creeping distance

and the effect of train speed on trace depth.The results show that:1)the movement of the train make airflow pressure distort

forming an uneven distribution;2)the trace depth is small in crosswind area but large in windward and leeward areas

where the minimum depth is in 50° direction of the crosswind area and the maximum depth is in 180° of the leeward area

and the trace depth is small on skirt edge but large on jacket;and 3)With train speed increasing

the trace depth slowly declines at first then decreases rapidly and returns to slow decline in the end

where the fastest decline rate of the trace depth appears in crosswind area

and the decline rate is higher in windward area than in the leeward area.