Micromachined Synthetic Jet Actuators And Applications Thereof
Allen, Mark G.
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The present invention involves micromachined synthetic jet actuators, or �microjet� actuators. These fluidic control devices may be fabricated using standard silicon micromachining techniques and comprise an orifice situated atop an actuator cavity which is bounded at least partially by a flexible membrane. Alternatively, microjets may be formed in more robust substrates, such as metals or ceramics. Vibration of the membrane using either electrostatic or piezoelectric drives results in a turbulent air jet formed normal to the microjet orifice. The jet stream is synthesized by a train of vortex rings. Each vortex is formed by the motion of the diaphragm and is advanced away from the jet under self-induced velocity. Alternatively, the microjet actuator can comprise a �piston in cylinder� to take the functional place of the vibrating diaphragm. This can be accomplished by changing the aspect ratio of the actuator cavity to a deeper, more cylindrical shape. A piston-like actuator can then be realized by using a �bossed� diaphragm. An improvement to microjets is the use of modulators with the jet actuators. Modulators are generally devices to selectively cover and uncover the orifice of a synthetic jet actuator in order to prevent either flow into or out of the jet cavity. Such modulators are fabricated as either vertical drive, lateral drive or constricting modulators.
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