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Electrospray drop formation
When a dielectric fluid is placed in a high electric field, a Taylor cone forms, and a thin stream of fluid is emitted from the tip. The stream breaks up into discrete micron-sized drops, as shown in the photograph. We are studying the formation of these drops, their size and velocity distributions as well as the mechanism by which the tip stream forms a three-dimensional cone.
To study the system, we illuminate the droplet stream using a short duration laser pulse. By exposing the drops twice in rapid succession, we can double-expose the image and determine the droplet velocity distribution as a function of the operating parameters of the Taylor jet (field strength, fluid conductivity, etc). |
Double-exposed image of drops emitted from a Taylor cone. The drops are
approximately 1 micron in diameter, and move at about 100 m/s (from left to right) |
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 Image of an electrojet, forming a whip-like jet which becomes unsteable and breaks in to droplets. If you look carefully, you can see the jet moving in and out of the imaging plane as it breaks up.
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This problem has many applications in technology, including material processing, drug manufacturing, and even space propulsion. |
