Characteristics of aerosol dispersion in isolation wards under the mixing and perforated ceiling air supplying ventilation strategies

In this paper, a numerical simulation study of the airflow organization and aerosol diffusion process in a typical isolation ward is carried out to explore the effects of mixing ventilation (MV) and perforated ceiling air supplying ventilation (PCV) strategies on aerosol diffusion and deposition in the ward. Furthermore, the effects of aerosol particle size (5μm, 20μm) and aperture ratio of perforated plate on aerosol distribution were studied in this paper. The simulation results show that: compared with the MV case, PCV results in a more uniform flow field and temperature field in the ward, and can increase the discharge speed of aerosol particles, which can effectively reduce the risk of cross-infection among medical staff; by counting the proportion of aerosol deposition, discharge and suspension on each surface in the ward, it can be found that small-sized aerosol particles (5μm) are more likely to diffuse and suspend in the ward under the influence of the flow field, while large-sized aerosol particles (20μm) are more likely to be deposited on the ground and on the bed under the influence of gravity; when using PCV, reducing the porosity of perforated plate can accelerate the deposition and discharge of aerosol particles, reduce the suspension of particles in the ward, and reduce the risk of virus infection in the air．