Atomization law and dust reduction effect of air-atomizing nozzles determined by CFD and experiments

Air-atomizing nozzles have a good effect on the deposition of respirable dust in airflow by producing fine and evenly distributed droplets. However, due to the lack of research on the atomization mechanism of air-atomizing nozzles, it is difficult to obtain spray parameters for improved dust reduction effects, which is hampering the development of ways to reduce coal mine dust. In this study, a combination of theoretical analysis, numerical simulation, experimental measurements, and field application was used to address this knowledge gap. The volume of fluid to discrete phase model was employed to accurately simulate the continuous atomization process of the internal and external flow fields of air-atomizing nozzles. Experiments were performed to determine the nozzle atomization characteristics. It was observed that with increasing air supply pressure, the degree of water flow fragmentation in the mixing chamber and the fluid domain near the nozzle area also increased. By considering the atomization angle, droplet size, concentration, velocity, and other characteristic parameters, the optimal air supply pressure was determined to be 0.4 MPa. The theoretical results were verified in Wangpo Coal Mine. When the air supply pressure was 0.4 MPa, the efficiency of respirable dust reduction reached 92.07 %, thus meeting the requirements for dust reduction.