Traveling Wave Actuators for Flow Control

Background:

Flow separation is typically associated with significant energy loss in engineering applications. For example, flow separation decreases lift and increases drag leading to stall for aerial vehicles, decreases the efficiency of fluid machinery such as fans, turbines, pumps, etc., or internal flows such as diffusers, expansions, etc. To avoid such losses and improve performance, there have been tremendous efforts to remove flow separation and reattach the boundary layer, referred to as flow control in engineering applications.

Technology Overview:

University at Buffalo and Texas A&M researchers have developed a piezoelectric actuator surface that generates traveling waves for active flow control.  The traveling wave actuator can be used to remove, reduce, or control flow separation.  In the figure, static stall occurs at about 10° Angle of Attack (AOA).  It is clear from this representation of the data that traveling waves at 167 Hz and 200 Hz are effective at delaying stall to at least 15˚ AOA. Where stall is delayed, the enhancement in lift coefficient compared with no actuation is as much as 66%. The standing waveforms at 12 Hz, and 78 Hz offer no apparent improvements in efficiency based on this experiment.

Advantages:

The traveling wave actuators perform better than actuators with pure periodic excitations (e.g., synthetic jets) because: i) traveling waves also inject momentum (generate thrust), and ii) apart from frequency, an additional parameter (wavelength) can also be tuned to affect the coherent structures.

Applications:

• Aircraft including passenger, military, and Unmanned Aerial Vehicles (UAV);
• Turbine blades including wind turbines, jets, propellers for aircraft, propellers for naval vessels;
• Marine vehicles including ship, boats, submarines, torpedoes;
• Spacecraft Launch and Re-entry vehicles.

Intellectual Property Summary:

PCT Patent Application PCT/US2020/038771 filed June 19, 2020.

Stage of Development:

Prototype demonstration.

Licensing Status:

Available for licensing.

Video Link:

Controlling flow separation using traveling wave actuation