Active Circulation Control for Wind Turbine Blades
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Solution Overview
Problem
Conventional Circulation Control methods for aerodynamic structures, such as wind turbine blades, require large mass flow rates of pressurized air, leading to high system costs and power requirements, and are not optimized for load-bearing performance.
Innovation Solution
Active Circulation Control (ACC) employs unsteady pulsed jets of chosen frequency and strength over convex/curved leading or trailing edges, combining with the Coandá effect to enhance lift, using zero-net mass flow active flow control actuators like synthetic jets or plasma actuators, reducing the need for pressurized air sources and minimizing system costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional circulation control uses steady pressurized air injection, then lift enhancement is achieved, but system cost and power requirements increase significantly
Solution Approach 1:
The patent applies periodic action by using unsteady pulsed jets instead of continuous steady injection. The pulsed jets are activated in oscillatory cycles, creating time-varying flow structures that enhance circulation control effectiveness while reducing average power consumption and system cost.
Solution Approach 2:
The patent implements dynamics by transitioning from static steady-state injection to dynamic unsteady pulsed injection. The system uses time-varying actuation frequencies and amplitudes to optimize lift enhancement, allowing adaptation to different operating conditions and reducing overall energy requirements.
2Force
If conventional circulation control uses high mass flow rates of pressurized air, then circulation control effectiveness is improved, but system cost increases
Solution Approach 1:
The patent uses periodic pulsed injection to achieve effective circulation control with reduced total mass flow. The oscillatory nature of the pulsed jets creates concentrated high-velocity flow structures during active phases, maintaining control effectiveness while reducing average mass flow rate requirements.
Solution Approach 2:
The patent changes the temporal parameters of fluid injection from continuous to pulsed, varying frequency and duty cycle to optimize performance. This parameter transformation allows achieving the same circulation control effect with lower overall mass flow rate of pressurized air.
3Stability of the object's composition
If steady wall-jet is used for circulation control, then flow attachment is maintained, but lift enhancement is limited compared to unsteady pulsed jets
Solution Approach 1:
The patent employs periodic pulsed injection to create unsteady flow structures that enhance lift beyond what steady injection can achieve. The oscillatory actuation generates dynamic vortex formation and wake modulation that increases circulation and lift enhancement while maintaining flow attachment through the Coandă effect during active phases.
Solution Approach 2:
The patent utilizes mechanical vibration principles by introducing high-frequency pulsed actuation that creates oscillatory flow structures. These unsteady vibrations in the fluid flow generate enhanced circulation patterns and vortex dynamics that increase lift enhancement compared to steady injection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
ACC achieves significant lift enhancement, up to 700% over conventional methods, with smaller, lighter actuators and reduced power requirements, while maintaining structural integrity and load-bearing capabilities, suitable for various aerodynamic structures including wind turbines.
Implementation Method 1
Active Circulation Control (ACC) employs unsteady pulsed jets of chosen frequency and strength over convex/curved leading or trailing edges, combining with the Coandá effect to enhance lift
Implementation Method 2
the unsteady momentum addition (and consequent vorticity production) combines with the acceleration of the fluid around the designed curvature (similar to the Coand{a} effect with a steady jet) to provide an instantaneous lift increase
Data Source
AI summary
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.