Simulation and evaluation method of dynamic wetting characteristics of dust suppression droplets on coal surface

Abstract

Spraying dust suppression liquid on the coal surface is a common dust suppression method for coal-related industrial enterprises, and the wetting process of dust suppression droplets impacting the coal surface is of great significance to the dust suppression effect. In order to study the dynamic wetting process of dust suppression droplets on the coal surface and further evaluate the wetting performance of droplets, the index of dynamic wettability during droplets impacting on the coal surface is proposed. The dynamic wetting process of droplets on the coal surface is investigated based on CLSVOF numerical simulation method. The wetting performance in the process is evaluated by using the dimensionless wetting length and the dimensionless wetting area, and the theoretical expressions of the maximum dimensionless wetting length and the maximum dimensionless wetting area are derived. At the same time, they are compared with the wettability evaluation ability of surface tension. The results show that the CLSVOF method can better simulate the impact and dynamic wetting process of droplets on the coal surface, and can be used to evaluate the dynamic wetting ability of different droplets on the coal surface under different conditions. The droplet drops on the coal surface, and first spreads as a disk. When the maximum spreading is reached, there is a velocity difference between the edge and the center of the disk droplet. When the velocity difference is small, the droplet retracts and coalesces into a sphere. When the velocity difference is large, the droplet breaks and forms many tiny droplets. And the larger the droplet size is, the earlier the breakage behavior appears and the more obvious the phenomenon is. Once the droplet breaks on the coal surface, the dimensionless wetting length and the dimensionless wetting area do not maintain the consistent trend, and the evaluation ability of the dimensionless wetting area is better. When the droplet size is the same, the larger the We number of droplet impacting the coal surface, the better the wetting ability. Increasing the droplet size at the same velocity has less effect on its wetting ability. Compared with surface tension, the dimensionless wetting length and dimensionless wetting area have better ability to evaluate wettability of droplets, which reflects the potential application value in the evaluation and optimization wetting agents.

Keywords

• droplet impact
• dynamic wetting
• dimensionless wetting parameters
• wettability evaluation
• clsvof