Recently, a fluidic facemask concept was proposed to mitigate the transmission of virus-laden aerosol and droplet infections, such as SARS-CoV-2 (COVID-19). This paper describes an experimental investigation of the first practical fluidic facemask prototype, or "Air-Screen". It employs a small, high-aspect-ratio, crossflow fan mounted on the visor of a filter-covered cap to produce a rectangular air jet, or screen, in front of the wearer's face. The entire assembly weighs less than 200 g. Qualitative flow visualization experiments using a mannequin clearly illustrated the Air-Screen's ability to effectively block airborne droplets (∼100 µm) from the wearer's face. Quantitative experiments to simulate droplets produced during sneezing or a wet cough (∼102 µm) were propelled (via a transmitter) at an average velocity of 50 m/s at 1 m from the mannequin or a target. The Air-Screen blocked 62% of all droplets with a diameter of less than 150 µm. With an Air-Screen active on the transmitter, 99% of all droplets were blocked. When both mannequin and transmitter Air-Screens were active, 99.8% of all droplets were blocked. A mathematical model, based on a weakly-advected jet in a crossflow, was employed to gain greater insight into the experimental results. This investigation highlighted the remarkable blocking effect of the Air-Screen and serves as a basis for a more detailed and comprehensive experimental evaluation.
Keywords: Air Screen; Airborne transmission; CDC, Centers for Disease Control and Prevention; ClO2, Chlorine dioxide; DEHS, DiEthyl-Hexyl-Sebacate; EUA, Emergency Use Authorizations; Face mask; Fluidic facemask; HEPA, High-efficiency particulate air; IGV, Inlet guide vane; LES, Large eddy simulation; NIOSH, US National Institute for Occupational Safety and Health; PVDF, Polyvinylidene difluoride; Personal protective equipment; RANS, Reynolds-Averaged Navier Stokes; SARS-CoV-2; WSP, Water-sensitive paper.
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