Wind Turbine Blade Pre-Bend With Inflection Points 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 existing solutions to reduce tower strikes and blade deflection are costly and inefficient.
Innovation Solution
A wind turbine blade design with a pre-bend configuration featuring two inflection points, altering the center of gravity location 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
1Strength
If the blade is made stiffer by adding more material, then blade deflection under aerodynamic load is reduced, but material costs and blade weight increase significantly
Solution Approach 1:
The blade is given a preliminary curved configuration (pre-bend) during manufacturing that positions the blade in an upwind direction. This pre-bend is designed so that under normal aerodynamic loading, the blade deflects downwind but maintains adequate clearance from the tower. The pre-bend allows the blade to be lighter while still preventing tower strikes under expected operating conditions.
Solution Approach 2:
The invention changes the geometric parameters of the blade by introducing specific curvature profiles with inflection points at defined locations along the blade span. This modifies the blade's structural behavior under load, allowing it to achieve the required clearance maintenance with reduced material compared to a straight blade design.
2Weight of moving object
If a pre-bend is introduced to maintain clearance and reduce blade weight, then material costs and weight are reduced, but moment loads on the pitch system increase significantly
Solution Approach 1:
The pre-bend is not uniform along the entire blade but is specifically configured with inflection points at particular locations (e.g., at 40% and 70% of the blade span from the root). This localized curvature distribution optimizes the balance between maintaining tower clearance and minimizing the moment arm that creates loads on the pitch system.
3Productivity
If the blade length is increased to improve energy production, then power generation capacity increases, but the risk of tower strike under high wind conditions increases
Solution Approach 1:
The pre-bend configuration is specifically designed for long blades to provide the necessary clearance from the tower throughout the blade's operational deflection range, enabling longer blades to be used safely without increasing tower strike risk.
Data Source
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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 (l2) 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.