Research on the multi-field coupling characteristics of sound- mist - dust of low-noise supersonic dust suppression spray based on porous foam materials

Supersonic aerodynamic spray dust removal technology has the advantages of high spray concentration, small droplet size and fast movement speed. It has good control over respirable dust, but it can cause severe high-frequency noise pollution. To solve this problem, the research team has carried out structural optimization and material optimization on the technical device (porous aluminum foam, porous stainless steel foam – 30–50 μm). The velocity flow field and sound field of each nozzle were simulated via COMSOL Multiphysics software.In combination with these experiments, verify the feasibility of porous absorption and attenuation nozzles; select nozzles with better noise reduction effects; study the spray noise characteristics and change rules of each nozzle under different aerodynamic pressures and water flow rates; and compare and analyze their dropper particle size, velocity and dust removal efficiency. The mechanism of noise induced by the supersonic flow of compressible fluid, the optimization of the supersonic flow field structure and the noise reduction of porous metal foam nozzles were revealed. The results showed that after the optimization of the supersonic flow field structure, the velocity in the nozzle and the thickness of each velocity layer were reduced so that the corresponding sound pressure level was reduced, the spray noise at the sound source was reduced by approximately 11.6 %, and the propagation direction was reduced by approximately 9.6 %. The rigid pore blocking effect of the microporous metal foam Laval nozzle greatly reduced the radial sound pressure level of the sound source propagating through the nozzle sidewall. Among them, the porous aluminum foam nozzle has the best noise reduction effect, In the direction of propagation, the sound pressure level in the middle and high frequency band is reduced by 16.3 %. With increasing aerodynamic pressure, the sound pressure level at each nozzle sound source and propagation direction increased. With increasing water flow, the sound pressure level of the nozzle at the sound source changed from the original value and then decreased to an upward trend. Under the same working conditions, the size of droplets in the droplet field of each nozzle was approximately 11 μm. When the dust removal time was 3 min, the dust removal efficiency of each nozzle was above 84 %. While ensuring the dust removal effect of the spray, the noise pressure level of the atomization process is reduced through structural optimization and the principle of porous absorption attenuation, which provides theoretical and technical support for the safe application of the supersonic aerodynamic dust removal spray and the collaborative control of dust and noise.