Two-Body Flexible-Tether OWC Design for Low-Mass Wave Energy Capture
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Solution Overview
Problem
Existing oscillating water column (OWC) designs face inefficiencies in energy conversion, high construction costs, and require excessive physical mass to maintain tether tension, limiting power capture and power-to-mass ratio.
Innovation Solution
A two-body tether-connected OWC design with a flexible tether system and a bottom heave plate that changes geometry or has an asymmetric shape, incorporating passive valves to manage water flow and air pressure for efficient energy conversion, using a bidirectional air turbine for power generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional OWC designs use excessive physical mass to maintain tether tension, then tether stability is improved, but power-to-mass ratio deteriorates
Solution Approach 1:
The patent applies dynamics by making the bottom body geometry changeable during operation. The bottom body transitions between different geometric configurations (e.g., from a more compact shape to an expanded shape) to dynamically adjust its added mass effect. This allows the system to optimize tether tension stability only when needed, rather than maintaining excessive mass continuously, thereby improving the power-to-mass ratio while preserving tether stability during critical phases.
Solution Approach 2:
The patent changes physical parameters of the bottom body by altering its geometry. By modifying the shape and volume of the bottom body, the system changes its hydrodynamic properties and added mass characteristics. This parameter change enables the system to achieve adequate tether tension with less physical mass, thus resolving the contradiction between stability and power-to-mass ratio.
2Ease of manufacture
If traditional OWC designs use symmetric bottom body geometry, then manufacturing simplicity is improved, but energy conversion efficiency deteriorates
Solution Approach 1:
The patent applies asymmetry by designing the bottom body with asymmetric geometry. The asymmetric shape creates different hydrodynamic responses during upward and downward motions, enabling the system to capture energy more effectively from both directions of wave motion. This asymmetric design improves energy conversion efficiency while remaining manufacturable through standard fabrication processes.
Solution Approach 2:
The patent makes the bottom body geometry dynamic and changeable rather than fixed. The bottom body can transition between different geometric configurations, allowing it to adapt its shape to optimize energy capture under varying wave conditions. This dynamic geometric adjustment enables efficient energy conversion without sacrificing manufacturing feasibility.
3Device complexity
If traditional OWC designs use fixed geometry bottom body, then structural simplicity is improved, but natural frequency tuning capability deteriorates
Solution Approach 1:
The patent applies dynamics by enabling the bottom body geometry to change during operation. This geometric transformation allows the system to adjust its natural frequency to match varying wave conditions. The dynamic structure consists of controllable elements that can reconfigure the bottom body shape, providing frequency tuning capability without requiring an excessively complex overall system architecture.
Solution Approach 2:
The patent changes physical parameters of the bottom body structure by altering its geometry. By modifying the shape, volume, and configuration of the bottom body, the system changes its hydrodynamic properties and natural frequency characteristics. This parameter adjustment capability enables the system to adapt to different wave conditions while maintaining reasonable structural complexity.
4Device complexity
If traditional OWC designs lack passive water flow management, then device simplicity is improved, but energy conversion efficiency deteriorates
Solution Approach 1:
The patent applies self-service by implementing passive water flow management through valves that automatically open and close based on pressure differential. The valves respond to the natural pressure changes during wave-induced motion, controlling water flow through the bottom body without requiring external control systems. This self-regulating mechanism improves energy conversion efficiency while adding minimal complexity to the overall device.
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
Enhances energy conversion efficiency, reduces construction costs, and optimizes power capture and power-to-mass ratio by tuning natural frequency to match wave conditions with minimal physical mass.
Implementation Method 1
a plurality of flexible tethers coupling the top body and the bottom body
Implementation Method 2
a bottom body comprising a bottom heave plate... with asymmetric effect... tuning natural frequency to match wave conditions
Implementation Method 3
a plurality of valves proximate to the plurality of openings... moves to a closed position with an upward motion of the bottom body to close the plurality of openings
Implementation Method 4
a power take-off system proximate to the open top end... air channel proximate to the open top end and the power take-off system
Implementation Method 5
Oscillating water columns (OWCs) are a type of wave energy converter that harness energy from the oscillation of seawater inside a chamber or hallow caused by the action of waves
Data Source
AI summary
An oscillating water column (OWC) includes a top body and a bottom body. The top body includes a hollow shape, an open top end, an open bottom end, a chamber traversing between the open top and bottom ends, a power take-off system proximate to the open top end, and an air channel proximate to the open top end and the power take-off system. The bottom body includes a bottom heave plate and a plurality of flexible tethers coupling the top body and the bottom body.