Wind Turbine Blade Root End Assembly Vacuum Evacuation
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Solution Overview
Problem
The manufacturing of wind turbine blade shell parts using vacuum assisted resin transfer moulding faces challenges such as dry spots and air pockets due to inefficient resin flow and evacuation, leading to potential structural weaknesses and increased cycle time, especially with larger blade lengths.
Innovation Solution
A method involving a root end assembly with fastening devices and a mounting plate that allows direct evacuation of air from the fibre material layup, using semipermeable materials to block polymer leakage, and a suction hose system for controlled vacuum application, enhancing resin impregnation and reducing the risk of air pockets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flexible vacuum bag is used to seal the mould cavity in VARTM, then the mould cavity can be evacuated to form underpressure for resin infusion, but dry spots and air pockets occur due to inefficient resin flow and evacuation
Solution Approach 1:
The invention divides the evacuation system into multiple segments by providing a plurality of vacuum outlets distributed across the mould cavity, rather than using a single vacuum outlet. This segmentation allows more efficient evacuation of air pockets from different regions of the mould cavity, preventing dry spots and ensuring complete resin impregnation of the fibre material.
2Reliability
If staff puncture the vacuum bag to inject liquid resin into dry spots, then air pockets can be eliminated, but this is very time-consuming and may cause deformations in the fibre material
Solution Approach 1:
The invention performs preliminary action by pre-positioning a plurality of vacuum outlets at strategic locations within the mould cavity before the infusion process begins. This preliminary configuration enables efficient air evacuation during the standard infusion process, eliminating the need for time-consuming post-infusion puncturing and resin injection operations to correct dry spots.
3Ease of manufacture
If staff stand on the vacuum bag to access large mould parts, then they can perform repairs, but this is not desirable as it may lead to deformations in the fibre material
Solution Approach 1:
The invention introduces an intermediary system - a rigid support structure with integrated vacuum outlets - that provides access to the mould cavity without requiring staff to stand on the flexible vacuum bag. The rigid support structure serves as a mediator between the staff and the mould cavity, enabling repair operations while maintaining the integrity and shape of the fibre material.
4Length of moving object
If larger moulds are used for increasingly longer wind turbine blades, then blades of more than 80 m can be manufactured, but the problem of dry spots is exacerbated
Solution Approach 1:
The invention applies segmentation by distributing multiple vacuum outlets across the large mould cavity area, creating multiple evacuation zones. This segmented approach ensures that even in large-scale moulds for blades exceeding 80 meters, air pockets can be efficiently evacuated from all regions, preventing dry spots and maintaining complete resin impregnation throughout the entire mould cavity.
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
This method significantly speeds up the evacuation process, improves resin distribution, and reduces the likelihood of air pockets and structural weaknesses, resulting in higher-quality wind turbine blade shell parts with reduced manufacturing time.
Implementation Method 1
the mould cavity is evacuated via the vacuum outlets so as to form an underpressure (also known as a negative pressure), such as for instance 5-10% of standard pressure, 101.3 kPa, preferably lower, in the mould cavity
Implementation Method 2
Resin inlets and vacuum outlets are connected to the mould cavity. First the mould cavity is evacuated via the vacuum outlets so as to form an underpressure (also known as a negative pressure), such as for instance 5-10% of standard pressure, 101.3 kPa, preferably lower, in the mould cavity, after which a supply of liquid resin is provided via the resin inlets. The resin is forced into the mould cavity at least due to the pressure differential, where it impregnates the fibre material.
Data Source
AI summary
The present invention relates to a method for manufacturing a wind turbine blade shell part made of a fibre-reinforced composite structure, including steps of mounting a plurality of fastening devices on a mounting plate to form a root end assembly, the mounting plate comprising one or more first openings for evacuating air; arranging the root end assembly over a mould surface of a mould; arranging an air-tight cover member so as to form a mould cavity; evacuating air from the mould cavity via at least the one or more first openings of the mounting plate; and supplying a polymer into the mould cavity and allowing the polymer to cure so as to form the composite structure. A root end assembly for use in the method is also provided.