Wind Turbine Blade Root Ovalization Prevention

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Solution Overview

Problem

Long wind turbine rotor blades exceeding 30 meters often experience ovalization due to the predominance of longitudinal reinforcement fibers, leading to stability issues during attachment to the hub and mechanical machining, such as drilling of holes.

Innovation Solution

A method involving the assembly of supporting rods in a circular shape with gaps for injection material and fibers, where the fibers are physically and chemically compatible, allowing for a stable connection and preventing ovalization through an insert molding process, using compatible molding tools to ensure proper alignment and bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If longitudinal reinforcement fibers are used in rotor blades exceeding 30 meters, then the blade can achieve sufficient strength for long-span support, but the root end experiences ovalization when subjected to gravity forces without support

Engineering Contradiction:

Improveblade strengthVSAvoidroot end shape

Core Design Contradiction:

StrengthVSShape

Solution Approach 1:

The invention applies preliminary action by placing circumferential fibers and supporting rods into the mold before the main injection molding process. These elements are positioned in advance to prevent ovalization of the root end during subsequent handling and mounting operations, rather than attempting to correct the shape after deformation occurs

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention uses composite materials by combining different types of fibers (longitudinal reinforcement fibers and circumferential stabilizing fibers) with the plastic matrix material. This multi-material approach allows the blade to simultaneously achieve the strength needed for long-span support and the shape stability required to prevent root end ovalization

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If pre-injected fibers are used in the molding process, then the fibers are pre-packaged and ready for injection, but the interconnection with later injected material is more difficult and weaker

Engineering Contradiction:

Improvefiber handlingVSAvoidinterconnection strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The invention applies segmentation by separating the circumferential fibers from the pre-packaged fiber bundles and placing them directly into the mold cavity. This allows the fibers to be positioned and connected to the main blade structure in a single injection process, ensuring strong interconnection rather than creating weak interfaces between separately injected materials

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If supporting rods are placed close together to prevent ovalization, then the root end stability is improved, but the gaps needed for injection material are reduced

Engineering Contradiction:

Improveroot end stabilityVSAvoidinjection material volume

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The invention applies local quality by positioning supporting rods and circumferential fibers specifically at the root end region where ovalization occurs, rather than uniformly distributing support elements throughout the entire blade. This localized reinforcement provides stability where needed while preserving injection material volume in other regions

Inventive Principle:

Principle #3Local quality

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 method produces a stable root end of the rotor blade that can withstand strong forces without ovalization, reducing manufacturing costs and time, while ensuring easy access for connection means like bushings.

Implementation Method 1

treating the injection material so that it bonds with the first fibres

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

first fibres in the gaps which first fibres are physically and/or chemically compatible with an injection material

Methodology Applied

Scientific EffectPhysical compatibility: Absorption (physical)

Implementation Method 3

the supporting rods firstly function as a support for the first fibres in between them

Methodology Applied

Scientific EffectMechanical support: Mechanical Force

Implementation Method 4

placing a first molding tool along an outer surface of the circular shape and a second molding tool along an inner surface of the circular shape

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS9878504B2Manufacture of a root section having supporting rods and fibers therebetween

Publication Date: 2018.01.30 SIEMENS GAMESA RENEWABLE ENERGY AS

AI summary

A supporting rod holding arrangement for manufacturing a root section of a rotor blade of a wind turbine is provided. The supporting rod holding arrangement includes an assembly of a plurality of supporting rods, each having an interface section for connecting to a hub interface of the wind turbine in an essentially circular shape such that there are gaps between the supporting rods, a plurality of first fibers in the gaps which plurality of first fibers are physically and/or chemically compatible with an injection material, and a holding device which holds the supporting rods in the essentially circular shape.