Collapsible Fairing Structure for Towed Line Drag Reduction
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Solution Overview
Problem
Marine survey systems face inefficiencies due to drag and strumming issues caused by lines such as cables and ropes when towed behind a vessel, which reduce the effectiveness of seismic and electromagnetic surveys by increasing resistance and energy loss.
Innovation Solution
A collapsible fairing surrounds the lines to reduce drag by changing the hydrodynamic shape presented to the water, using a telescoping or accordion-like design that maintains a foil or diamond cross-section to minimize vortex shedding and drag, allowing for smoother operation without the need for additional sections or labor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lines such as cables and ropes are used to tow marine survey equipment, then the equipment can be deployed and retrieved, but drag and strumming increase resistance and energy loss
Solution Approach 1:
A collapsible fairing is introduced as an intermediary component that surrounds the line. The fairing has a streamlined foil or diamond cross-section that cuts through water smoothly, reducing vortex shedding and drag on the line while allowing the line to pass through its center. This mediator protects the line from water resistance without interfering with the towing function.
Solution Approach 2:
The fairing is designed to be collapsible rather than rigid. It can be extended when the line is deployed to provide drag reduction, and collapsed when the line is retrieved to minimize resistance during winching. The dynamic structure adapts to different operational states, optimizing performance for both deployment and retrieval phases.
2Loss of energy
If a streamlined cover is extended to reduce drag, then hydrodynamic efficiency improves, but the apparatus requires space and mechanical complexity for extension and retraction
Solution Approach 1:
The fairing is constructed from multiple collapsible sections or panels that can fold together. These segmented sections allow the fairing to compress into a compact form when retracted, while still forming a complete streamlined shape when extended. The segmentation enables space-efficient storage and reduced mechanical complexity compared to a solid telescoping structure.
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 collapsible fairing significantly reduces drag, enhancing the efficiency of marine survey operations by minimizing energy loss and maintaining system integrity during extension and retraction, with a drag coefficient reduction from 1.5 to 2.3 to 0.40 to 0.55, and overall drag reduction by a factor of approximately 5 for systems with multiple lines.
Implementation Method 1
using a telescoping or accordion-like design that maintains a foil or diamond cross-section to minimize vortex shedding and drag
Data Source
Figure 1
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Figure 2B
AI summary
A system can include a float, a winch, a line, and a collapsible fairing. The winch can be coupled to the float. The line can be associated with the winch, where the winch is configured to extend and retract the line. The collapsible fairing can surround the line. Extension and retraction of the line can cause the collapsible fairing to extend and collapse.