Curved Flange Wedge Design for Wind Turbine Tower Connections
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Solution Overview
Problem
Bolted flange connections in large tower structures, such as wind turbine towers, face challenges with structural strength, fatigue resistance, nut loosening due to vibrations, and corrosion from dynamic loads and water ingress.
Innovation Solution
A flange connection design featuring a ring-shaped flange element with a wedge and heel surface, providing a wedge surface angle and heel surface angle that together create a static behavior under dynamic loads, preventing water ingress and maintaining contact to prevent corrosion, and utilizing a transition region with a curved shape to reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flat flange connections are used to connect tower sections, then the structure can be assembled, but the bolts experience dynamic loads causing fatigue, prying effects, and nut loosening under wind-induced vibrations
Solution Approach 1:
The flange connection uses a curved or spherical contact surface instead of a flat surface. The flange has a contact surface with a radius of curvature that allows it to conform to the cylindrical tower section, creating a curved bearing surface that distributes loads more evenly and eliminates prying effects on the bolts during dynamic loading
Solution Approach 2:
The invention changes the geometric parameters of the flange connection by introducing a curved contact surface with specific radius of curvature. This parameter change transforms the load distribution pattern from concentrated (flat flange) to distributed (curved flange), reducing stress concentrations and preventing bolt fatigue
2Ease of operation
If bolts are used to connect flange sections, then the connection can be assembled and disassembled, but water ingress causes corrosion of the bolts
Solution Approach 1:
The curved flange contact surface acts as an intermediary sealing element between the two tower sections. The conformal contact created by the curved surface provides a natural seal that prevents water ingress to the bolted joint, eliminating the need for additional sealing components while maintaining disconnectability
3Productivity
If large tower sections are connected with bolted flanges, then the tower can be built in practical lengths, but the nuts loosen during operation due to vibrations from wind flow
Solution Approach 1:
The curved contact surface of the flange creates a self-centering effect that maintains uniform bolt loading during vibration. The spherical geometry allows the flange to naturally align and distribute dynamic loads evenly across all bolts, preventing the differential loading that causes nut loosening in conventional flat flange connections
Data Source
AI summary
A flange element for a flange connection with a longitudinal centre axis A includes a flange part and an attachment part. The flange part has a front side with a front surface. The attachment part is adapted for secure attachment to a tubular element comprising a tower section of the tower structure for a wind turbine or a pipe element that is part of an offshare load bearing structure. The flange part is arranged radially on the inside of the flange element and is provided with a flange wedge. The flange wedge includes a flange wedge surface that is part of the front surface, and a flange heel including a flange heel surface that is part of the front surface. The flange wedge surface makes a wedge surface angle α1 and the flange heel surface makes a heel surface angle β with a plane P that is perpendicular to the longitudinal centre axis A of the flange element.