Pivotable Foil Sections for Trawl Door Hydrodynamic Control
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Solution Overview
Problem
Conventional trawl doors lack versatility and ease of control in adjusting spreading force and depth during water activities, with existing systems being cumbersome, vulnerable, and limited in remote adjustment capabilities, especially in trawl fishing and seismic surveys.
Innovation Solution
A spreading device with multiple foils, where at least one foil has moveable sections that can pivot relative to stationary foils, creating overlapping channels that alter water flow and hydrodynamic characteristics, allowing for adjustable drag resistance and lift force, enabling remote control of deflection angles for optimal fishing or survey operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional trawl doors use fixed foils, then structural simplicity is maintained, but spreading force and depth control are limited
Solution Approach 1:
The foil is divided into multiple sections that can pivot independently relative to each other. Each section can be adjusted to change the overall foil shape and hydrodynamic characteristics, enabling variable spreading force without requiring multiple complete foils.
Solution Approach 2:
The foil structure transitions from a fixed, static configuration to a dynamic, adjustable configuration. The pivotable sections allow the foil to change its shape and angle of attack during operation, adapting to different fishing conditions and depth requirements.
2Adaptability or versatility
If mechanical drive mechanisms are integrated into the trawl door structure, then foil adjustment capability is achieved, but device weight increases
Solution Approach 1:
Instead of providing full mechanical drive mechanisms at all adjustment points, the invention uses gravity and water current forces to assist the pivoting action. The drive mechanism only needs to overcome initial friction and provide small corrective forces, significantly reducing its weight and complexity.
Solution Approach 2:
The trawl door structure utilizes the natural forces of water current and gravity to assist in the pivoting of foil sections. The hydrodynamic forces themselves help move the foils to the desired positions, reducing the burden on mechanical drive mechanisms.
3Ease of operation
If remote control capability is added to trawl doors, then operational flexibility improves, but system vulnerability and complexity increase
Solution Approach 1:
The invention replaces complex electronic remote control systems with a simplified mechanical cable-pulley system. The cables run through protective conduits along the trawl door structure, providing reliable mechanical actuation that is less susceptible to electromagnetic interference, water damage, and electronic failures.
Solution Approach 2:
Protective conduits and cable routing systems serve as intermediaries between the control mechanism and the external environment. These intermediaries protect the control cables from damage while transmitting the control forces to the foil sections.
4Adaptability or versatility
If foil sections are made movable to alter water flow patterns, then hydrodynamic control improves, but structural stability may be compromised
Solution Approach 1:
The pivotable sections are designed with different structural characteristics at different locations. The pivot points and connecting structures are reinforced to handle the local stresses, while the foil sections themselves maintain their hydrodynamic shape. Each section has the structural quality needed for its specific position and function.
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 design enhances the control over spreading force and depth, allowing for precise adjustments during operations without stopping, improving fishing efficiency and survey capabilities by altering water flow patterns and hydrodynamic properties.
Implementation Method 1
The spreading force, which is the lateral force (lift force) exerted by a trawl door for spreading the mouth of the trawl net
Implementation Method 2
creating overlapping channels that alter water flow and hydrodynamic characteristics
Implementation Method 3
the drag/resistance and speed through the water the spreading device exerts on the ship pulling the towed device
Data Source
AI summary
A spreading device for trawl fishing, seismic survey operations or other water activities where it is desirable to keep distance between two sides of a towed device is provided, the spreading device having at least one part comprising two or more foils, where each foil has a front surface and a rear surface, the surfaces each being defined by two edges and two side limitations, in use being front and rear edges, an upper and lower side limitations connected to respective upper and lower frames, where at least one foil is stationary and where one or more sections of another foil is pivotably connected to the another foil, such that the section may be moved from a position where the surface of the section is flush with the surface of the another foil, to a position where the surface is out of plane with the surface of the another foil.