No abstract

The Falling Droplet device was used to measure the extensional viscosity of a variety of aqueous polymer solutions. These solutions were atomized with the miniature "inverse" twin-fluid atomizer. Droplet size measurements were made with a Malvern laser diffraction particle sizing device. Droplet sizes measured did not rank strictly according to either lowshear rate shear viscosity or extensional viscosity.

Detailed compressible airflow analysis reveals that the minimum air supply conditions for sonic exit flow were not met in previous visualization experiments on the triple-concentric atomizer. Phase/Doppler measurements of droplet size and velocity in both water and polymer solution sprays show that the polymer solution spray has slightly larger mean drop sizes that the water spray. Even this slight effect is important, however, especially when considering that the polymer content was only 0.05% by weight.

Improvements to the Falling Droplet apparatus for measuring the extensional viscosity of liquids are complete. A one-component Phase Doppler Particle Analyzer has been refurbished and installed for measurements of droplet size and axial velocity in sprays of nonaqueous liquids.