Active circulation control of aerodynamic structures
Active Circulation Control (ACC) of aerodynamic structures, such as a turbine blade, uses unsteady or oscillatory flow from either synthetic jets or pulsed jets to modify a velocity profile of the blade. The blade includes an opening disposed in a surface of the blade at a location proximate to a trailing edge, a leading edge, or both the trailing edge and the leading edge of the blade. An active flow control device in fluid communication with the opening produces a wall-jet of pulsed fluid that flows over the trailing edge, the leading edge, or both the trailing and leading edges of the blade and modify the velocity profile of the blade.
1. A wind turbine comprising:
a wind turbine blade comprising
an opening disposed in an outer surface of the wind turbine blade proximate a curved trailing edge of the wind turbine blade, and
active flow control devices disposed in the wind turbine blade and in fluid communication with the opening and configured for producing unsteady wall-jets of pulsed fluid that flows over the curved trailing edge, wherein the unsteady wall-jets of pulsed fluid comprise velocities and frequencies sufficient to adjust the overall lift of the wind turbine blade; and
a control system for providing active flow control instructions to the active flow control devices that vary with respect to changing wind speeds, changing structural loads of the wind turbine, or combinations thereof, wherein the active flow control instructions comprise modifying the velocity of the pulsed jets and selectively activating available ones of the active flow control devices.
2. The wind turbine of claim 1 , wherein the active flow control devices comprise localized zero mass flow actuators within at least one housing proximate the trailing edge.
3. The wind turbine of claim 2 , wherein the localized zero mass flow actuators comprise synthetic jets, each comprising a synthetic jet housing, a flexible diaphragm situated within the synthetic jet housing, and a synthetic jet actuator for activating the diaphragm.
4. The wind turbine of claim 3 , wherein the synthetic jets comprise dual bimorph synthetic jets.
5. The wind turbine of claim 3 , wherein the synthetic jet actuators are selected from the group consisting of a piezoelectric transducer, a waveform/sinusoidal drive transducer, a thermostatic actuator, a thermoelectrical actuator, a thermopneumatic actuator, a shape memory alloy, or a combination thereof.
6. The wind turbine of claim 1 , wherein the opening extends up to about 80% of the length of the wind turbine blade.
7. The wind turbine of claim 1 , wherein the opening is located at a distance of up to about 30% of a chord length from the trailing edge of the wind turbine blade.
8. The wind turbine of claim 1 , wherein the overall lift increase comprises an instantaneous overall lift increase.
9. The wind turbine of claim 1 , further comprising at least one instrument for measuring operating data of the wind turbine.
10. The wind turbine of claim 9 , wherein the controller uses the operating data for generating the active flow control instructions that vary with respect to changing wind speeds.