Surge Plates for Tension-Leg Platform Wave Load Reduction
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Solution Overview
Problem
Existing Tension-Leg Platforms (TLPs) designed for offshore wind turbines face challenges in managing wave-induced accelerations, leading to increased structural loads and costs due to the neglect of mass augmentation, which can spiral out of control if not optimized properly.
Innovation Solution
The method involves attaching surge plates to the submerged structure of TLPs to increase horizontal added mass by displacing water, optimizing their size and placement to minimize wave loading and reduce accelerations without affecting tendon pretension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the buoyant volume is increased to provide higher net buoyancy and maintain tendon pretension, then the platform stability is improved, but the wave loads increase which causes the design to spiral out of control
Solution Approach 1:
The patent changes the mass parameter of the platform by adding surge plates, increasing the horizontal added mass from 0 to a positive value. This modifies the dynamic response characteristics without changing the buoyant volume, thereby reducing wave-induced accelerations while maintaining stability.
Solution Approach 2:
The surge plates create an additional mass effect that replicates the inertia of water being accelerated with the platform. This copied mass effect reduces the platform's acceleration response to wave forces without requiring additional buoyant volume.
2Force
If the platform mass is increased to reduce wave induced accelerations, then the internal loads are reduced, but the required buoyant volume increases which attracts more wave loads
Solution Approach 1:
The patent changes the horizontal added mass parameter by introducing surge plates, increasing it from zero to a positive value. This parameter change reduces wave-induced accelerations and internal loads without increasing the buoyant volume, thereby avoiding the penalty of increased wave loads.
Solution Approach 2:
The surge plates act as an intermediary element that couples the platform to the surrounding water mass. They transfer some of the wave force into accelerating water, which reduces the direct force transmission to the platform structure and lowers internal loads.
3Force
If surge plates are added to increase horizontal added mass, then the platform accelerations are reduced, but the device complexity increases
Solution Approach 1:
The patent segments the added mass function into separate surge plates that can be independently designed and positioned. These plates are attached to specific locations on the platform structure, allowing the complexity to be distributed and optimized rather than requiring a completely redesigned platform.
Solution Approach 2:
The surge plates are positioned at specific locations on the platform where they provide maximum benefit for reducing accelerations. The local quality of the structure is enhanced at these positions with vertical plates that optimize the horizontal added mass effect without unnecessarily complicating the entire platform design.
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 approach reduces platform accelerations, enabling a lighter and cheaper design by increasing effective horizontal mass, thus lowering internal loads and maintaining stability without increasing buoyant volume or pretension requirements.
Implementation Method 1
attaching surge plates to the submerged structure of a TLP to displace water when the platform accelerates horizontally, thereby increasing the horizontal added mass
Implementation Method 2
displace water when the platform accelerates horizontally
Implementation Method 3
minimum buoyant volume: to provide the net buoyancy to float the mass of the platform, tower, and wind turbine
Data Source
AI summary
Tension-leg platforms for supporting wind turbines are augmented with surge plates. The surge plates increase the amount of water that is displaced when a tension-leg platform is accelerated horizontally, which reduces wave induced accelerations. The surge plates are mounted to the deepest parts of the submerged structure of each platform to minimize wave loading.