PARTICLE DEPOSITION IN BIFURCATING AIRWAY MODELS WITH VARYING AIRWAY GEOMETRY

Local deposition efficiencies and deposition patterns of aerosol particles were studied experimentally in single bifurcation tube models with varying geometry. The diameter ratio (DR) of the daughter to parent tube was varied from 0.64 to 1.0 and a local obstruction was also imposed in some of the models. Monodispersed oil particles (size range = 3-7 mum dia.) tagged with uranine were generated as test aerosols and were drawn through the model at flow rates corresponding to Reynolds number (Re) of 283-3397. It was found that deposition of particles took place mainly on and in the immediate vicinity of the bifurcation ridge for Stokes number (Stk) greater-than-or-equal-to 0.03 regardless of tube geometries used. Deposition efficiency (DE) in the bifurcation region increased with increasing Stk but did not change with branching angles between 30-degrees and 45-degrees. The diameter ratio showed only a minor effect on DE. The results suggest that Stk may be the single most important factor for particle deposition in the bifurcating airways in the inertial regime.