Law of effect of acoustic wave propagation angle on spray dust suppression efficiency

In underground mining operations, the generation of a substantial quantity of coal dust is a common occurrence. To mitigate the potential adverse effects of coal dust on the working environment, miners’ ealth, and mechanical equipment, a simulation experimental platform for synergistic dust suppression using acoustic waves and water spray was utilized. The distribution characteristics of the acoustic field at different angles, the dust suppression efficiency for total dust and PM₁₀ coal dust, and the variation of coal dust concentration with the acoustic wave angle were investigated using a multi-channel sound power testing system, a TSI8533 aerosol monitor, a coal mine dust sampler, and a scanning electron microscope. The influence of the acoustic wave propagation angle on the dust suppression effect was explored. Additionally, the agglomeration characteristics of coal dust by spray droplets under different angles were comparatively analyzed. The results indicate that as the acoustic wave angle increases, the acoustic field distribution initially converges towards the upper part of the roadway. When acoustic wave angle is greater than or equal to 60°, the acoustic pressure level of the sound field begins to shift downward. The total dust is predominantly distributed in the middle area of the simulated roadway, while PM₁₀ particles are primarily concentrated in the upper-middle area of the simulated roadway. The results demonstrate that as the acoustic wave angle increases, the total dust concentration initially rises and then declines. The highest dust suppression efficiency is achieved when acoustic wave angle is 0°, with the efficiency increasing from 74.80% for water spray alone to 85.97%. For PM₁₀, the concentration initially decreases and then increases with the increase in acoustic wave angle, with the lowest concentration occurring at an acoustic wave angle of 30°. The dust suppression effect of acoustic waves combined with water spray is optimal at this angle. Compared with water spray alone, the dust suppression efficiencies for PM₁, PM_2.5, PM₄ and PM₁₀ are increased by 31.10%, 31.87%, 33.49% and 30.90%, respectively. The results further show that as the acoustic wave angle increases, the total dust concentration initially increases and then decreases. The highest dust suppression efficiency is achieved when the acoustic wave angle is 0°, with the efficiency increasing from 74.80% for water spray alone to 85.97%. For PM₁₀, the concentration initially decreases and then increases with the increase in the acoustic wave angle. The lowest concentration occurs at an acoustic wave angle of 30°. The agglomeration effect of PM₁₀ is the best at this angle, with the most small particles attached and the agglomerate size reaching up to 36 μm. The study elucidates the mechanism by which the acoustic wave angle affects the dust suppression effect of water spray, thereby providing a theoretical basis for the field application of the combination of acoustic waves and water spray.