The drag coefficient, CD, was experimentally determined during sedimentation of aerosol particles in air flowing horizontally in a conduit of rectangular cross section, and its relation to the Reynolds numbers for the particle, Rep, and the conduit, Rec, was found. The method used to obtain the frictional force on the particles is based on observation of the trajectories of the particles being deposited on the bottom wall of the conduit. The diameter (dp) and point of deposition of the particles were determined by examining small glass slides distributed along the floor of the apparatus at given positions. The diameter of particles adhering to these laminae can be observed by microscope, but a factor must then be applied to convert these values to the diameters in suspension (dp), since the particles are liquid and undergo flattening as they collect on the glass. Results were compared with the aerodynamic diameter of the particle, obtained independently, and the discrepancies that appeared will need to be investigated further. The velocity profiles of the air inside the apparatus were also recorded. A correlation of the form CD = f(Rep, Rec) is proposed.
drag coefficient measurement; aerosol particles
