Wind Turbine Rotor Blade Porous Trailing Edge Noise Reduction

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Solution Overview

Problem

Wind turbine rotor blades generate significant noise, particularly at the trailing edge due to boundary layer detachment, and existing noise reduction methods are complex and difficult to produce or maintain on a large scale.

Innovation Solution

A rotor blade design featuring a Velcro strip along its longitudinal direction, which acts as a porous body to reduce noise by delaying flow separation and increasing lift, while being easier to manufacture and maintain than traditional designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If complex trailing edge geometries are used to modify boundary layer properties, then noise reduction is achieved, but manufacturing complexity and repair difficulty increase significantly

Engineering Contradiction:

Improvenoise emissionVSAvoidtrailing edge geometry complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies a porous body at the trailing edge of the rotor blade to modify boundary layer properties. The porous structure allows controlled flow through it, delaying flow separation and reducing trailing edge noise without requiring complex geometric shapes. This resolves the contradiction by achieving noise reduction through material porosity rather than geometric complexity.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The porous body is designed as a replaceable component that can be easily removed and replaced. Instead of modifying the entire trailing edge geometry permanently, the patent uses a detachable porous element that can be swapped out for maintenance or replacement, significantly reducing repair difficulty and cost while maintaining noise reduction performance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Object-affected harmful factors

If traditional noise reduction methods are implemented, then trailing edge noise is reduced, but mass production becomes difficult and maintenance becomes complicated

Engineering Contradiction:

Improvetrailing edge noiseVSAvoidmass production capability

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The noise reduction solution is segmented into a separate porous body component rather than being integrated into the main blade structure. This segmentation allows the porous body to be manufactured independently using standard processes, then attached to the blade, enabling mass production of both the blade and the noise reduction component separately.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The porous body acts as an intermediary component between the blade structure and the airflow. This intermediary element can be easily manufactured, attached, and replaced without affecting the main blade structure, simplifying both manufacturing and maintenance processes while effectively reducing trailing edge noise.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Force

If the boundary layer detaches at the trailing edge, then lift is generated, but separation noise increases significantly

Engineering Contradiction:

ImproveliftVSAvoidseparation noise

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The porous body at the trailing edge modifies the boundary layer behavior by allowing controlled flow through its porous structure. This delays flow separation and reduces the intensity of separation noise while maintaining the lift-generating flow patterns, effectively decoupling lift generation from noise generation.

Inventive Principle:

Principle #31Porous materials

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 Velcro strip effectively reduces noise emission and increases lift by shifting noise frequencies to higher, more absorbable ranges, and its ease of production and maintenance makes it a cost-effective solution for wind turbines.

Implementation Method 1

The hook-and-loop fastener used according to the invention represents an example of a porous body that is suitable for reducing noise emissions and simultaneously contributes to improving maximum lift by delaying flow separation

Methodology Applied

Scientific EffectPorosity: Porosity

Implementation Method 2

shift the frequency of the generated noise towards higher frequencies that are more readily absorbed by the surrounding air

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentEP3844385B1Rotor blade for a wind turbine and wind turbine

Publication Date: 2023.10.11 WOBBEN PROPERTIES GMBH

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Figure 3a~4

AI summary

The present invention relates in particular to a rotor blade (200) having an inner blade portion which extends from a rotor blade root (209) in the longitudinal direction of the rotor blade (200), and an outer blade portion which adjoins the inner blade portion and which extends in the longitudinal direction up to a rotor blade tip (210), wherein the rotor blade (200) has a pressure-side face (200c) and a suction-side face (200b) which are separated from one another by a leading edge (202) and a trailing edge (201), a velcro-type fastener being arranged on a surface of the rotor blade (200) and extending essentially along the longitudinal direction of the rotor blade (200). The velcro-type fastener (300) serves to reduce noise and/or increase the lift of the rotor blade (200).