External Annular Air Curtain to Mitigate Aerosol Pollutants in Wet-Mix Shotcrete Processes

Dust generation from wet-mix shotcrete (WMS) is a major source of aerosol pollutants in underground construction. However, research on aerosol pollutant control equipment during the WMS process is still scarce. To achieve effective control of aerosol pollution during WMS production, this study introduced and applied air curtain dust suppression technology. A multi-dimensional jet test platform was used to investigate the dust suppression effects of a direct air curtain, an inner ring wall-attached air curtain, and an outer ring wall-attached air curtain during WMS production. By analyzing the variation characteristics of the dust concentration curve, key characteristic points were determined, and the diffusion phase and sedimentation phase were demarcated. With the incorporation of a K-C air curtain, the range reduction rates for the diffusion and sedimentation phases reached 51.92% and 80.85%, respectively, with an aerosol control efficiency of 57.10%. Additionally, numerical simulation was conducted to investigate the flow field characteristics during WMS production. It was found that the radial velocity gradient of the entire flow field in the spatial coordinate system was reduced, with a maximum reduction rate of 57% at (Y-axis = 560 mm). Furthermore, the affected area of the vorticity in the main jet shear layer was significantly reduced.