Multi-Inflection Pre-Bent Wind Turbine Blade for Lower Pitch Loads
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Solution Overview
Problem
Conventional pre-bent wind turbine blades experience significant moment loads on the pitch system, leading to premature wear and failure, and current solutions to reduce tower strikes and deflection are costly and inefficient.
Innovation Solution
A wind turbine blade design with a pre-bend configuration featuring at least two inflection points along its centre line axis, shifting the centre of gravity to reduce moment loads and maintain aerodynamic stability, using a mould assembly to shape the blade during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional pre-bent wind turbine blades are used to maintain clearance between blade and tower, then tower strike risk is reduced, but moment loads on the pitch system increase significantly
Solution Approach 1:
The blade is designed with non-uniform pre-bend characteristics along its length, with different bend amounts and inflection points in different sections. The first pre-bend section has a first amount of pre-bend while the second pre-bend section has a second amount of pre-bend, creating localized flexibility zones that reduce overall moment loads on the pitch system while maintaining tower clearance.
Solution Approach 2:
The blade incorporates multiple inflection points that allow dynamic adjustment of the blade's aerodynamic center during operation. The inflection points enable the blade to adapt its flexing behavior under varying wind loads, reducing the oscillating moment loads transmitted to the pitch system while maintaining adequate clearance from the tower.
2Object-affected harmful factors
If blade stiffness is increased by adding more material to reduce deflection and tower strike risk, then clearance is maintained, but material costs and blade weight increase
Solution Approach 1:
Instead of increasing material quantity to boost stiffness, the invention changes the geometric parameters of the blade by incorporating specific pre-bend configurations with inflection points. This allows the blade to achieve appropriate deflection characteristics and maintain tower clearance through optimized shape rather than increased mass, reducing both material costs and blade weight.
3Weight of moving object
If pre-bent blade design is used to reduce material usage and weight, then manufacturing costs decrease, but moment loads on the pitch system increase
Solution Approach 1:
The pre-bend is applied locally in specific sections of the blade rather than uniformly throughout. The first and second pre-bend sections are positioned at different locations along the blade length, creating targeted flexibility zones that reduce overall blade weight while the distributed inflection points work together to reduce moment loads on the pitch system.
Solution Approach 2:
The blade is segmented into multiple pre-bend sections with distinct inflection points. This segmentation allows each section to contribute differently to the overall flexibility and load distribution, reducing the cumulative moment loads on the pitch system while maintaining the weight reduction benefits of the pre-bent design.
Data Source
AI summary
A wind turbine blade (40) for a wind turbine (10) includes an elongate body (42) defining a root end (44), a tip end (46), a leading edge (56), and a trailing edge (58). The elongate body (42) further defines a pitch axis (60) and a blade centre line axis (64) extending along a length of the blade (40). The blade centre line axis (64) defines a pre-bend in the blade (40), wherein the curve that defines the blade centre line axis (64) includes at least a first inflection point (I1) and a second inflection point (I2) between the root end (44) and the tip end (46) of the blade (40). A method of making a wind turbine blade (40) having a blade centre line axis (64) with multiple inflection points is disclosed and a moulding assembly (80) for making the pre-bent wind turbine blade (40) is also disclosed.