Helix Rope Drag Reduction via Strand Count Optimization
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Solution Overview
Problem
The high operational costs and drag issues associated with helix ropes used in pelagic trawls lead to reduced efficiency and increased fuel consumption, making them less favorable despite their environmental benefits.
Innovation Solution
A helix rope with a braided sheath formed from 18 to 24 strands, which reduces drag at typical angles of attack for pelagic trawl mesh, thereby lowering fuel consumption and increasing trawl mouth opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If helix ropes with braided sheath are used in pelagic trawls, then environmental benefits and self-spreading capability are improved, but drag increases and fuel consumption increases
Solution Approach 1:
The patent changes the physical parameters of the rope by increasing the strand count from typical conventional numbers to 18-24 strands, and optimizes the braid angle to 15-30 degrees. These parameter changes modify the rope's hydrodynamic properties to reduce drag while preserving the self-spreading capability that provides environmental benefits.
Solution Approach 2:
The patent employs composite construction by combining multiple strands of fishing line or rope in a braided configuration around a strength member core. This composite structure allows the rope to achieve both the self-spreading function and reduced drag characteristics by optimizing the interaction between the braided sheath and water flow.
2Ease of manufacture
If conventional braided ropes are used, then manufacturing cost is reduced, but drag and fuel consumption are not optimized
Solution Approach 1:
The patent modifies manufacturing parameters by specifying 18-24 strands and 15-30 degree braid angles, which are achievable with standard braiding equipment. These parameter changes create a rope that maintains manufacturability and cost-effectiveness while significantly reducing drag compared to conventional designs.
3Loss of energy
If rope strand count is increased to 18-24 strands, then drag reduction is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the braided sheath into 18-24 individual strands, each contributing to the overall drag reduction. This segmentation allows the complex function of drag reduction to be achieved through multiple simpler elements working together, while the modular nature maintains manufacturing feasibility.
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 modified helix rope design achieves significant drag reduction, leading to lower fuel costs, increased efficiency, and greater customer demand for environmentally positive self-spreading trawls.
Implementation Method 1
form a series of cambered sections capable of either or both causing lift and reducing drag when such rope is subjected to water flow
Implementation Method 2
form a series of cambered sections capable of either or both causing lift and reducing drag when such rope is subjected to water flow
Data Source
Figure 1~11
Figure 1A
AI summary
A pelagic trawl having mesh formed from helix rope that includes a strength member core (37) comprising a braided strength member surrounded by a braided sheath (398) wherein the braided sheath (398) is formed of several strands (397) and one of the strands is significantly larger in diameter than the other strands so as to form a series of cambered sections capable of either or both causing lift and reducing drag when such rope is subjected to water flow about the rope in a position that corresponds to a position assumed by ropes used in forming pelagic trawl mesh in pelagic trawls, the strength member core strands are of a less obtuse braid angle than the strands forming the braided sheath. Also provided is a method for forming a pelagic trawl formed from such helix rope.