Available Technology

Advanced High Performance Piezoelectric Hybrid Synthetic Jet Actuators

NASA Langley Research Center has invented three serial advanced high performance piezoelectric hybrid synthetic jet actuators. These inventions will provide active flow control for current and future wing-borne vehicles in subsonic, transonic and supersonic flow. Effective active flow control...
Patent Abstract: 
These inventions relate to active flow control, which is an effort to change the paradigm of aerodynamic design of current and future wing-borne systems in subsonic, transonic and supersonic flow. Active flow control will be an inherent input to the conceptual design of the next generation of commercial and military flight vehicles. Retrofitted to current fixed-wing aircraft, active flow control can clean up complex three-dimensional external flow separations on the wing top surface particularly severe under maneuvering conditions. The outcome is a reduction in overall drag of the vehicle, alleviation of unsteady loads, and prevention of the expulsion of the inlet shock system (that may lead to catastrophic loss of the airframe). Synthetic jet actuators produce a jet flow using the surrounding air rather than relying on a secondary fluid. The interaction of synthetic jets with an external cross flow over the surface on which they are mounted can displace the local streamlines and can induce an apparent or virtual change in the shape of the surface, thereby effecting flow changes on length scales that are one to two orders of magnitude larger than the characteristic scale of the jets. The present inventions comprise high performance, zero-net mass-flux, synthetic jet actuators for active control of viscous, separated flow on subsonic and supersonic vehicles. These inventions are piezoelectric actuators in which all the walls of the chamber are electrically controlled synergistically to reduce or enlarge the volume of the synthetic jet actuator chamber in three dimensions simultaneously. The jet velocity and mass flow rate for the actuators will be from several times up to a couple of orders magnitude higher than conventional piezoelectric actuators. The actuator can be designed either in the horizontal (fig. 1) or vertical position (fig. 3). The actuator can also be designed as a curved chamber, instead of the conventional cylinder chamber, to reduce the dead volume of the jet chamber and increase the efficiency of the synthetic jet (fig. 2).
Jet velocity and mass flow rate several times up to a couple of orders magnitude higher than conventional piezoelectric actuators -Can be used on both subsonic and supersonic vehicles -Can be installed on wing surfaces
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