Abstract
Air curtain is an efficient device for cutting off airflow and confining contaminants. Inspired by the ability, a circulated air curtain composed of end-to-end plane jets generated by a relay of air pillars is proposed to confine exhaled contaminants in this study. Furthermore, the optimization study of computational fluid dynamics (CFD) is conducted to explore cutting-off performance and find better design parameters under different conditions, i.e., human-curtain distance, enclosure shape, jet velocity from air pillar, and exhalation modes. The multidirectional blockage and vortex-like rotative transmission routes of exhaled airflow are observed when air curtain exists. Results indicate that contaminants are concentrated around the source. The average mole fraction of exhaled contaminants outside air curtain under different human-curtain distance decreases 4.3%–19.6% compared to mixing ventilation with same flux. Shortening the human-curtain distance can improve the performance of air curtain and may change the direction of exhaled airflow. Moreover, It has better performance when the enclosure shape is close to a circle. Higher jet velocity is better for improving the confinement performance, but the trend is not very obvious as velocity increases. For exhalation modes, it is more challenging to control exhaled contaminants for intense exhalation activity (such as coughing) in steady simulation, but results in transient simulation show better performance when coughing only once. These results can provide a reference for the subsequent design and improvement in applying air curtain in hospital wards or other places, especially during the period of flu outbreak.
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Abbreviations
- C d :
-
drag coefficient
- d p :
-
particle diameter
- \({\vec F}\) :
-
additional acceleration (force/unit particle mass) term
- g :
-
gravity acceleration
- Re :
-
relative Reynolds number
- S ϕ :
-
the source terms
- Γ ϕ :
-
the diffusion term
- \({\vec u}\) :
-
fluid phase velocity
- \({{\vec u}_{\rm{p}}}\) :
-
particle velocity
- μ :
-
fluid molecular viscosity
- ρ :
-
fluid density
- ρ p :
-
particle density
- ϕ :
-
general scalar quantity
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Acknowledgements
The work was supported by the National Natural Science Foundation of China (No. 51778128), the National Key Research and Development Program of China (2018YFC1200100) and the Entrepreneurship Leadership Project in Guangzhou Development Zone of China (CY2018-003).
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Wang, H., Qian, H., Zhou, R. et al. A novel circulated air curtain system to confine the transmission of exhaled contaminants: A numerical and experimental investigation. Build. Simul. 13, 1425–1437 (2020). https://doi.org/10.1007/s12273-020-0667-5
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DOI: https://doi.org/10.1007/s12273-020-0667-5