Constant-Force Mooring Line for Offshore Turbine Orbital Motion
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Solution Overview
Problem
Offshore wind turbines face issues with mooring lines experiencing varying tension due to changing wave and weather conditions, leading to potential dragging of the turbine structure relative to orbital velocity, which is not addressed by existing designs.
Innovation Solution
A mooring system comprising a weight and float combination that maintains a substantially constant force, utilizing a parallelogram linkage or pulley system to provide a balanced downward and upward force, ensuring the turbine's orbital motion under varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid mooring line is used, then the turbine structure is constrained, but the turbine is dragged through the water relative to orbital velocity
Solution Approach 1:
The mooring line incorporates a dynamic element (float or spring) that allows the line to flex and adjust its length dynamically. This enables the turbine to maintain orbital motion while still being restrained by the mooring system, resolving the contradiction between structural constraint and motion freedom.
2Stability of the object's composition
If a rigid mooring line is used, then the turbine is restrained, but surge acceleration is created from heave acceleration
Solution Approach 1:
The dynamic mooring line with float or spring element absorbs heave acceleration through vertical motion, preventing this acceleration from being transmitted as surge acceleration to the turbine. The system dynamically adjusts to wave motion while isolating the turbine from harmful acceleration forces.
3Speed
If constant tension is provided, then orbital motion is maintained, but the mooring line requires complex tensioning mechanism
Solution Approach 1:
The float acts as a counterweight that provides constant upward buoyant force to maintain tension in the mooring line. This passive counterweight mechanism eliminates the need for complex active tensioning systems while maintaining the tension necessary for orbital motion.
Solution Approach 2:
The float or spring element automatically adjusts the mooring line tension based on its own physical properties (buoyancy or spring constant) without requiring external control systems. The system self-regulates to maintain constant tension, simplifying the overall 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
The system maintains a constant tension on the mooring line, preventing surge acceleration and keeping the turbine structure stable by counteracting orbital motion, even in storm conditions.
Implementation Method 1
The downward force of the weight is substantially equal to the displacement force of the float. The float and weight, when coupled are neutrally buoyant.
Implementation Method 2
The downward force of the weight is substantially equal to the displacement force of the float
Implementation Method 3
A second mooring line descends from the turbine structure, passes over a pulley at the float, and terminates at a hanging weight
Data Source
AI summary
A mooring line that provides substantially constant force, also referred to a mooring line that is always soft, allows the orbital motion of a moored turbine structure under varying wave conditions and is suitable for storm conditions when the turbine is not operating. A mooring line with substantially constant force does not create surge acceleration from heave acceleration and does not cause the turbine structure to be pulled through the water relative to orbital velocity.