Wind Turbine Blade Sawtooth Trailing Edge for High-Speed Noise Reduction
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Solution Overview
Problem
Existing wind turbine blades, particularly those with longer lengths, generate significant aerodynamic noise, especially from turbulent boundary layers at the trailing edge, with conventional sawtooth designs offering limited noise reduction and increasing noise at high wind speeds.
Innovation Solution
A blade noise reduction device featuring sawtooth units with secondary teeth on both sides of primary teeth, where the secondary teeth have a smaller addendum angle, along with a connection body and guide ribs, to guide eddy currents and enhance noise reduction while maintaining rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat triangular sawtooth trailing edge is used, then the blade structure is simple and easy to manufacture, but the noise reduction effect is limited (0-2 dBA) and noise increases at high wind speeds
Solution Approach 1:
The sawtooth trailing edge is divided into multiple levels: a first-level sawtooth structure and second-level sawtooth structures on both sides. This multi-level segmentation creates more complex flow separation patterns that reduce aerodynamic noise more effectively than simple single-level sawtooth structures, achieving over 4 dBA noise reduction at peak sound power levels.
Solution Approach 2:
The second-level sawtooth structures are asymmetrically distributed on both sides of the first-level sawtooth, with different addendum angles optimized for their respective positions. This asymmetric design creates favorable vortex patterns that enhance noise reduction while maintaining structural integrity.
2Object-generated harmful factors
If the addendum angle of secondary teeth is reduced to guide eddy currents, then the noise reduction effect is improved, but the rigidity of the primary tooth may be compromised
Solution Approach 1:
Different addendum angles are applied to different levels of sawtooth structures. The first-level sawtooth maintains a larger addendum angle for structural rigidity, while the second-level sawtooth structures have smaller addendum angles optimized for guiding eddy currents and enhancing noise reduction. This local differentiation allows simultaneous optimization of strength and noise reduction performance.
3Power
If the blade length is increased to increase single-unit capacity, then the power generation capacity is improved, but the radiated noise of the blade increases
Solution Approach 1:
The trailing edge is segmented into multi-level sawtooth structures that create controlled flow separation and vortex formation. This segmentation disrupts the turbulent boundary layer at the trailing edge, reducing aerodynamic noise from large-megawatt blades while maintaining their power generation capacity.
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
The solution achieves a substantial noise reduction of over 4 dBA at peak sound power levels, with improved noise reduction at high wind speeds and enhanced aerodynamic performance by widening the flow wake and accelerating vortex pair interactions.
Implementation Method 1
the addendum angle of the secondary tooth is smaller than an addendum angle of the primary tooth, to help to guide an eddy current in the air
Implementation Method 2
the noise mainly comes from an aerodynamic noise of the blade, especially noise from a turbulent boundary layer at a trailing edge
Data Source
AI summary
A blade noise reduction device, comprising a plurality of sawtooth units. The plurality of sawtooth units are arranged in a first direction. Each sawtooth unit comprises secondary teeth and a primary tooth, which extend in a second direction, wherein at least one secondary tooth is distributed on each of two sides of the primary tooth, the tooth vertex angle of the secondary tooth being smaller than the tooth vertex angle of the primary tooth. The blade noise reduction device can remarkably improve the noise reduction effect. In addition, the present invention further relates to a blade having the blade noise reduction device, and a wind turbine generator set having the blade.