| dc.description |
For piezoelectric stack (PZT) driven droplet generator, the driving waveform
and driving frequency effect on liquid filament shape and droplet characteristics have
been experimentally studied. The experimental study was based on a PZT driven
droplet generator with known geometric design parameters and working fluid
properties. A lumped-element-model (LEM) constructed to study the acousticmechanical
behavior of the droplet generator. The droplet generator volumetric
rejection from experimental study compared with that from LEM. Results show that
LEM can predict the internal acoustic-mechanical behavior with reasonable accuracy.
Based on the LEM, the PZT displacement magnitude dominates the internal pressure
variation within the chamber. However due to the natural response of droplet generator,
the acoustic pressure in the droplet generator decays exponentially. Experimental data
show that the droplet formation process can be waveform and frequency dependent.
When the droplet formation process is driven in "low frequency" regime, droplet
formation process is weakly affected by frequency. Meniscus interaction effects, which
are the interaction of a liquid filament from different droplet generation cycles, on
droplet formation process are present when droplet formation process is driven in "high
frequency" regime. Due to the meniscus interaction effect, the droplet formation
process at "high frequency" is waveform and frequency dependent. Results show that
the droplet volume reduces slightly with PZT driving frequency, about 20%. Droplet
velocity increases with driving frequency, about 40%. However the droplet break-off
time and droplet velocity are weakly affect by the driving frequency. |
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