The atomization of nozzles plays a crucial role in improving the efficiency of spraying for dust suppression. According to the inertia collision theory for dustfall, the droplets with small particles and high-velocity possess a greater capacity for capturing dust, which requires a relatively higher speed of spraying at the outlet of the nozzle. Along the line of dustfall-droplet-velocity-structure, this study employs COMSOL Multiphysics software to simulate the internal characteristics of velocity field for a direct jet nozzle under different pressures and confirms that the convergence angle α and length-to-diameter ratio C of the outlet channel are the two main structural factors affecting velocity variation. A single-factor test is conducted for studying the characteristics of fluid migration under different nozzle structure parameters, and it is found that with other parameters unchanged, the smaller α is, the more slowly the jet velocity increases in the axial direction, and the more stable the jet velocity becomes in the radial direction; while the smaller C is, the more rapidly the jet velocity increases in the axial direction, but there was no obvious variation in the radial direction. As the simulation results shows, when α = 30° or C = 2, the average velocity at the nozzle’s outlet reaches the highest level and the velocity at the outlet of the convergence angle also becomes higher. Phase Doppler interferometer can be used to measure the velocity variation in the spray field, and the nozzle’s atomization performance could be obviously improved by optimizing the shrinkage angle α. Therefore, the priority should be given to the value of α in designing dustfall nozzles.

喷嘴的雾化在提高喷雾抑制粉尘的效率方面起着至关重要的作用。根据用于粉尘的惯性碰撞理论，具有小颗粒和高速的液滴具有较大的粉尘捕获能力，这需要在喷嘴的出口处以相对较高的喷射速度进行喷射。沿着尘滴-液滴-速度-结构线，本研究使用COMSOL Multiphysics软件模拟了在不同压力下直喷喷嘴的速度场的内部特性，并确认了收敛角α和C的长径比C出口通道是影响速度变化的两个主要结构因素。为了研究不同喷嘴结构参数下的流体迁移特性，进行了单因素测试，可以发现，在其他参数不变的情况下，α越小，则射流速度沿轴向增加的速度越慢，射流速度沿径向方向变得越稳定。而较小的C是，射流速度在轴向方向上增加得更快，但是在径向方向上没有明显的变化。如仿真结果所示，当α  = 30°或C  = 2时，喷嘴出口处的平均速度达到最高水平，并且会聚角出口处的速度也变高。相位多普勒干涉仪可用于测量喷雾场中的速度变化，并且通过优化收缩角α可以明显改善喷嘴的雾化性能。因此，在设计除尘喷嘴时应优先考虑α的值。