Vaporizing Microdroplet Inhalation,Transport,and Deposition in a Human Upper Airway Model

摘要

Evaluation of injuries from inhalation exposure to toxic fuel requires detailed knowledge of inhaled aerosol transport and deposition in human airways.Focusing on highly toxic,easily volatized JP-8 fuel droplets,the three-dimensional airflow,temperature distributions,and fluid-particle thermodynamics,i.e.,droplet motion as well as evaporation,are simulated and analyzed for laminar as well as locally turbulent flow conditions.Specifically,usinga commercial finite-volume software with user-supplied programs as solver,the Euler-Lagrange approach forthe fluid-particle thermodynamics is employed with :(1) a low Reynolds numbe rk-omicron model for laminar-to-turbulent airflow,and (2)a stochastc model for random fluctuations in the droplet trajectories with droplet evaporation.Presently,tehrespiratory system consists of two major segments of a simplified human cast replica,i.e.,a representatie oral airway from mouth to trachea (Generation 0) and a symmetric four-generation upper bronchial tree model (G0 to G3).Experimentally validated computational fluid-particle thermodynamcis results show that evaporation of JP-8 fuel droplets is greatly affecting deposition in the human airway.Specifically,droplet deposition fractions due to vaporization decrease with increasing ambient temperatures and decreasing inspiratory flow rates.It is also demonstrated that assuming idealized velocity profiles and particlej distributions in or after the trachea may greatly overpredict particlej deposition efficiencies in the upper bronchial tree.