Fluidics (also known as Fluidic logic) is the use of a
fluidor compressible medium to perform analog or digitaloperations similar to those performed with electronics.
The physical basis of fluidics is
pneumaticsand hydraulics, based on the theoretical foundation of fluid dynamics. The term Fluidics is normally used when the devices have no moving parts, so ordinary hydraulic components such as hydraulic cylindersand spool valvesare not referred to as fluidic devices. The 1960s saw the application of fluidics to sophisticated control systems, with the introduction of the fluidic amplifier.
A jet of fluid can be deflected by a weaker jet striking it at the side. This provides non-linear amplification, similar to the
transistorused in electronic digital logic. It is used mostly in environments where electronic digital logic would be unreliable (e.g., systems exposed to high levels of electromagnetic interferenceor ionizing radiation). Nanotechnologyconsiders fluidics as one of its instruments. In this domain, effects such as fluid-solid and fluid-fluid interface forces are often highly significant. Fluidics have also been used for military applications
The basic concept of the fluidic amplifier is shown here. A fluid supply, which may be air, water, or hydraulic fluid, enters at the bottom. Pressure applied to the control ports C1 or C2 deflects the stream, so that it exits via either port O1 or O2. The stream entering the control ports may be much weaker than the stream being deflected, so the device has
Given this basic device, flip flops and other
fluidic logicelements can be constructed. Simple systems of digital logic can thus be built.
Fluidic amplifiers typically have bandwidths in the low
kilohertzrange, so systems built from them are quite slow compared to electronic devices.
The fluidic triode is an amplification device that uses a
fluidto convey the signal.
Although much studied in the laboratory they have few practical applications. Many expect them to be key elements of
Fluidic triodes were used as the final stage in the main
Public Address systemat the 1964 New York World's Fair.
Fluidic components appear in some hydraulic and pneumatic systems, including some automotive
automatic transmissions. As digital logichas become more accepted in industrial control, the role of fluidics in industrial control has declined.
Fluidic injection is being researched for
thrust vectoringin aircraft jet enginenozzles, and for ships. Such systems divert thrust via fluid effects [http://www.afrlhorizons.com/Briefs/Apr04/OSR0303.html] [http://www.geocities.com/m_mason007/home.html] [http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000123000003000502000001] . Tests show that air forced into a jet engine exhaust stream can deflect thrust up to 15 degrees. Such nozzles are desirable for their lower: mass and cost (up to 50% less), inertia(for faster, stronger control response), complexity (mechanically simpler, no moving parts or surfaces), and radar cross sectionfor Stealth. This will likely be used in many unmanned aircraft, and 6th generation fighter aircraft.
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