# Study on Airflow Field Distribution and Dust Distribution Characteristics at Blast Piles
## 3 Results and Discussion
### Analysis of Dust Generation Characteristics and Particle Size Distribution from Blast Piles
#### 3.2.2 Influence Characteristics of Wind Speed on the Airflow Field at Blast Piles  
To analyze the impact of wind speed on the flow field at a single blasting pile, a geometric model of a single blasting pile platform was established as shown in Figure 12, considering the actual situation and the requirements of computational simulation. This model mainly consists of a fluid domain and a single blasting pile platform. The fluid domain is a cuboid with one corner removed, with a length of 55 m, a width of 10 m, and a height of 60 m. The single platform is a slope composed of two rectangles, with dimensions as shown in the figure. The blasting pile is simplified into a dust-producing surface of 1 m \(\times\) 1 m. Based on the analysis of the airflow field at blasting pile platforms of various levels, under most natural wind speeds, the wind speed reaching a single blasting pile is not excessively high. Therefore, this section will select three inlet wind speeds of 0, 1, and 3 m/s to calculate and simulate the flow field distribution at a blasting pile platform.  
As shown in Figure 13, using the plane parallel to the dust-producing surface of the blasting pile and the X-Z plane as observation surfaces, wind speed vector diagrams and the trajectory distributions within the entire fluid domain are plotted for wind speeds of 0, 1, and 3 m/s. It can be observed from the figures that the airflow field distributions for wind speeds of 1 and 3 m/s are very similar and differ significantly from that of 0 m/s. When the  
Figure 11: v = 1, 9 and 17 m/s: (**a**) Wind velocity at dump side, (**b**) Vector of wind speed at dump side, (**c**) Wind velocity at stope side, (**d**) Vector of wind speed at stope side.  
inlet wind speeds are 1 and 3 m/s, the airflow trajectory diagrams and wind speed vector diagrams show that the airflow flows upward along the slope where the dust-producing surface is located. After passing over the slope, the airflow trajectory gradually returns to a gentle state. With the same ventilation volume, the cross-sectional area at the top of the slope is the smallest, resulting in the highest wind speed. Close to the ground on the top platform, the airflow direction remains upward, leading to a very low wind speed. At the same time, a vortex is generated near the ground, and as can be seen from the pressure contour plot, the vortex area corresponds to the low-pressure zone. However, there is no vortex generation or sudden changes in wind speed on the far side of the top platform.  
Figure 12: Geometric model of single explosion reactor platform.  
Figure 13: Flow field distribution under different wind speeds.  
When the inlet wind speed is close to 0 m/s, there is almost no airflow movement in the entire fluid domain, with only weak airflow moving near the dust-producing surface of the blasting pile, and the airflow moves downward along the slope. There is no airflow movement at the position above the dust-producing surface along the slope or on the top platform of the blasting pile, and no vortices are generated. This is completely different from the airflow field distribution when the inlet wind speeds are 1 and 3 m/s. By comparing the airflow field distributions at the blasting pile platform under the two working conditions, we can know that when the inlet wind speed is 0 or extremely low, no vortex field will be generated at the blasting pile platform, and there will be no situation where the cross-sectional area is small and the wind speed increases.