fluidics

 

branch of engineering and technology concerned with the development of equivalents of various electronic circuits using movements of fluid rather than movements of electric charge. The basic devices used in fluidics are specially designed valves that, like transistors, can be arranged to act as amplifiers and logic circuits. The principal advantage of fluidic systems is that they can be designed to tolerate conditions under which electronic systems could not possibly operate. For example, a fluidic system could operate in the exhaust of a rocket, using the exhaust as its working fluid. Fluidic systems are also advantageous where the system output is to be a flow of fluid, as in a carburetor.

Fluidics (also known as Fluidic logic) is the use of a fluid or compressible medium to perform analog or digital operations similar to those performed with electronics.

The physical basis of fluidics is pneumatics and 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 cylinders and spool valves are 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 transistor used 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 interference or ionizing radiation).

Nanotechnology considers fluidics as one of its instruments. In this domain, effects such as fluid-solid and fluid-fluid interface forces are often highly significant.

Among other firms, Bowles Fluidics Corporation in Columbia, Maryland, USA, specializes in the manufacture of fluidic parts. Notable examples of fluidic technology application in everyday life include windshield-wiper nozzles, spa jet nozzles, and massage chair controller systems. Fluidics have also been used for military applications

Amplifier

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 gain.

Given this basic device, flip flops and other fluidic logic elements can be constructed. Simple systems of digital logic can thus be built.

Fluidic amplifiers typically have bandwidths in the low kilohertz range, so systems built from them are quite slow compared to electronic devices.

Triode

The fluidic triode is an amplification device that uses a fluid to convey the signal.

Although much studied in the laboratory they have few practical applications. Many expect them to be key elements of nanotechnology.

Fluidic triodes were used as the final stage in the main Public Address system at the 1964 New York World's Fair.

Systems

Fluidic components appear in some hydraulic and pneumatic systems, including some automotive automatic transmissions. As digital logic has become more accepted in industrial control, the role of fluidics in industrial control has declined.

Fluidic injection is being researched for thrust vectoring in aircraft jet engine nozzles, and for ships. Such systems divert thrust via fluid effects[1][2][3]. 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 section for Stealth. This will likely be used in many unmanned aircraft, and 6th generation fighter aircraft.

See also

• Microfluidics

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