BREAKUP OF DROPLETS OF NEWTONIAN AND NON-NEWTONIAN FLUIDS

High-speed photography and impaction cards have been used to enhance k nowledge of the manner in which droplets of Newtonian and non-Newtonia n fluids break up in a high-speed jet of air. The photographs show tha t breakup was initiated for both types of fluid by the formation of wa ves on the surface of droplets exposed to the air stream, with frequen cy which depended on the velocity of the air jet, and with bags ill th e low-velocity regions behind the droplet and downstream of the peaks of the wave. The waves were subsequently stripped to form ligaments, i nitially joined by bags to form a web of ligaments and later separated into two parts as their central regions stretched and droplets were f ormed within a distance of 20 diameters of the original droplet. The n on-Newtonian fluids have been categorized in terms of critical speed o f breakup which increased with the addition of a copolymer to a critic al velocity of 540 m/s. It is likely that higher concentrations of the copolymers than those examined here will lead to higher critical velo cities, Additional experiments established that initial droplet diamet ers from 2 to 4 mm and the height from which the droplet fell into the air stream, 20 mm to 1 m had little effect on the critical speed.