Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Microdroplet Impact Dynamics at Very High Velocity on Face Masks for COVID-19 Protection

코로나-19 보호용 페이스 마스크에서의 액적 고속 충돌 거동

  • Choi, Jaewon (School of Mechanical Engineering, Soongsil University) ;
  • Lee, Dongho (School of Mechanical Engineering, Soongsil University) ;
  • Eo, Jisu (School of Mechanical Engineering, Soongsil University) ;
  • Lee, Dong-Geun (School of Mechanical Engineering, Soongsil University) ;
  • Kang, Jeon-Woong (School of Mechanical Engineering, Soongsil University) ;
  • Ji, Inseo (School of Mechanical Engineering, Soongsil University) ;
  • Kim, Taeyung (School of Mechanical Engineering, Soongsil University) ;
  • Hong, Jiwoo (School of Mechanical Engineering, Soongsil University)
  • 최재원 (숭실대학교 기계공학부) ;
  • 이동호 (숭실대학교 기계공학부) ;
  • 어지수 (숭실대학교 기계공학부) ;
  • 이동근 (숭실대학교 기계공학부) ;
  • 강전웅 (숭실대학교 기계공학부) ;
  • 지인서 (숭실대학교 기계공학부) ;
  • 김태영 (숭실대학교 기계공학부) ;
  • 홍지우 (숭실대학교 기계공학부)
  • Received : 2021.10.31
  • Accepted : 2021.12.14
  • Published : 2022.05.01
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Abstract

Facial masks have become indispensable in daily life to prevent infection and spread through respiratory droplets in the era of the corona pandemic. To understand how effective two different types of masks (i.e., KF-94 mask and dental mask) are in blocking respiratory droplets, i) we preferentially analyze wettability characteristics (e.g., contact angle and contact angle hysteresis) of filters consisting of each mask, and ii) subsequently observe the dynamic behaviors of microdroplets impacting at high velocities on the filter surfaces. Different wetting properties (i.e., hydrophobicity and hydrophilicity) are found to exhibit depending on the constituent materials and pore sizes of each filter. In addition, the pneumatic conditions for stably and uniformly dispensing microdroplets with a certain volume and impacting behaviors associated with the impacting velocity and filter type change are systematically explored. Three distinctive dynamics (i.e., no penetration, capture, and penetration) after droplet impacting are observed depending on the type of filter constituting the masks and droplet impact velocity. The present experimental results not only provide very useful information in designing of face masks for prevention of transmission of infectious respiratory diseases, but also are helpful for academic researches on droplet impacts on various porous surfaces.

코로나 팬데믹 시대에서 비말(respiratory droplet)을 통한 감염 및 확산을 막기 위해 마스크는 없어서는 안 될 생활 필수품이 되었다. 본 연구에서는 두 가지 다른 타입의 마스크(KF-94 마스크와 덴탈 마스크)가 비말 차단에 얼마나 효과적인지를 파악하기 위하여, i) 각각의 마스크를 구성하고 있는 필터의 젖음성(wettability) 특성을 분석하고, ii) 필터 표면에 빠른 속도로 충돌하는 미소 액적의 동적 거동 특성을 실험적으로 관찰하였다. 각 필터의 구성 재료에 따라 상반된 젖음성 특성, 소수성(hydrophobicity) 또는 친수성(hydrophilicity)을 보임을 확인하였다. 또한, 일정 체적을 갖는 미소 액적을 안정적으로 토출하는 공압 조건을 탐색하고 액적의 충돌 속도 변화에 따른 액적 충돌 거동 변화를 분석하였다. 마스크를 구성하고 있는 필터의 종류와 액적 충돌 속도에 따라 i) 필터를 통과하지 못하거나(no penetration), ii) 필터에 포획(capture)되거나, iii) 필터를 통과(penetration)하는 등의 다른 충돌 후 거동을 보임을 확인하였다. 이러한 결과들은 비말 차단용 마스크 디자인에 있어 매우 기본적이고 유용한 정보를 제공할 뿐만 아니라, 다양한 다공성 표면에서의 액적 거동에 대한 학문적 연구에도 도움이 될 것으로 판단된다.

Keywords

Acknowledgement

이 논문은 2020년도 정부(교육부)의 재원으로 한국연구재단의 지원을 받아 수행된 기초연구사업임(No. 2020R1F1A1066664).

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