Study on contamination characteristics of roof insulators under artificial simulated fog-haze and airflow environment

Abstract

As the environment deteriorates, the frequency of fog-haze weather is getting higher and higher, which greatly affects the normal life of the people and the normal operation of highspeed railway external insulation equipment. The fog-haze is a combination of fog and haze. The haze in the air will affect pollution accumulation of the roof insulator, and the fog in the air which settles on the surface of the roof insulator will make the pollution on the surface of the roof insulator humid. This kind of humid contamination greatly increases the probability of the roof insulator's flashover. The roof insulator, as an important external insulation device for electrified railways, will cause a serious impact on the stable operation of high-speed trains in the event of failure. However, there are few studies on the contamination situation under the fog-haze and airflow environment of the roof insulator. In this paper, the FQJG2-30/16 roof insulator is used as the test object, and the force of the fog-haze particles on the surface of the insulator under the highspeed air smog environment is analyzed. It is believed that the force of the fog-haze particles mainly includes gravity, airflow drag, collision force between particles and friction between the particles and the surface of the insulator, as the same time the water film formed by the water droplets in the haze environment causes the fog-haze particles to settle on the insulator. The adhesion of the surface is increased, leading to more serious surface area contamination of the roof insulator. Based on this, a simulation model of fog-haze particles deposition on the surface of insulators in a high-speed airflow for-haze environment was established. the artificial fog-haze environment was simulated under different airflow speeds by through the artificial climate chamber to study the contamination of the roof insulator. In this paper, (NH 4 ) 2 SO 4 was used to simulate the soluble salt in the haze, and the insoluble matter was simulated by diatomaceous earth. The (NH 4 ) 2 SO 4 : diatomaceous earth = 1:6 configuration haze, 0.5 g salt, 3 g ash was selected. The water mist generated by the ultrasonic water mist generator simulates the fog in the fog-haze environment, and the influence of the haze environment on the roof insulator contamination at different airflow speeds is revealed by artificially simulating the airflow haze environment roof insulator contamination test. The simulation and test results show that in the fog-haze environment, there is a difference in surface area contamination of the roof insulator under different airflow speeds. When the air velocity is less than 30m/s, the water droplets are more likely to form a water film on the surface of the roof insulator, so that the fog-haze particles are more likely to adhere to the surface of the insulator, and the insulator surface contamination is continuously reduced as the airflow speed increases, when the airflow speed is greater than 30m/s, the highspeed airflow takes away a large number of water droplets, and the surface of the roof insulator is not easy to form a water film. At this time, the effect of the water droplet adhesion force is reduced, the airflow drag force is greater than the water droplet adhesion force, and the fog-haze particles are more prone to slip on the surface of the insulator. When the airflow speed reaches 80m/s, there is almost no fog-haze particle deposition on the roof insulator surface. Therefore, the research work in this paper can provide theoretical support for the safe and stable operation of high-speed train roof insulators.