Atomizer nozzle
An atomizer nozzle can take on many forms. The first atomizer nozzle also called a aspirator nozzle was invented by Dr. Thomas DeVilbiss of Toledo, OH in the late 1800s for producing a fine spray of a liquid based on the Venturi effect. His device was used for spraying medicine on the back of his patient's throats. Atomizer nozzles can create atomization from a variety of mechanical means, which includes but is not limited to: electrostatics processes, ultrasonic nozzle and centrifugal forces.
Principle of operation
When a gas is injected under pressure through a tube with a decreasing section, it speeds up, generating a pressure drop at the narrowest point (due to Bernoulli's principle).
The reduced pressure, due to the pressure difference between the two points, sucks up a liquid from a reservoir through a narrow tube into the moving gas flow, and projects it forward as a fine spray of droplets (although not atoms as the name suggests).

They may be automated or manually operated, the latter being typically by means of a manual pump (rubber ball or piston), this being a traditional type of atomizer used for perfume.
Applications
Atomizer nozzles are used for spraying perfumes, for applying paint, in fuel injection systems, and in spray drying installations.

See also
Notes