Marine Fairing Flap Design for Drag Reduction
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Solution Overview
Problem
Marine survey lead-in cables experience significant drag and 'strumming' due to vortex shedding, which hampers the efficiency of hydrocarbon exploration operations.
Innovation Solution
The use of fairings with a main body portion and a flap portion that weathervane around the cables, altering the hydrodynamic shape to reduce drag and vortex shedding, coupled with an adhesive system for quick and efficient installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-in cables are used to connect survey streamers to the tow vessel, then electrical and optical signal transmission is enabled, but drag and vortex-induced strumming increase
Solution Approach 1:
A fairing acts as an intermediary hydrodynamic element that envelops the lead-in cable. The fairing's streamlined shape and flaps intercept and manage water flow, reducing vortex shedding and drag forces on the cable while allowing the cable itself to remain intact for signal transmission.
Solution Approach 2:
The fairing employs flexible flaps that can rotate or deflect to adapt to varying flow conditions. These thin-walled structures reduce form drag and suppress vortex formation by smoothing flow separation, thereby reducing energy loss without compromising the cable's function.
2Ease of operation
If lead-in cables are deployed in the water, then survey streamers can be towed, but vortex shedding causes strumming vibrations
Solution Approach 1:
The fairing serves as a protective intermediary between the water flow and the lead-in cable. By positioning the streamlined fairing around the cable, it mediates the interaction between water and cable, reducing vortex shedding and resulting strumming vibrations while preserving towing capability.
Solution Approach 2:
The fairing employs curved, streamlined surfaces that guide water flow smoothly around the cable. This curvature reduces flow separation and vortex formation, thereby minimizing strumming vibrations during towing operations.
3Reliability
If traditional fairing installation methods are used, then cable protection is achieved, but installation time and complexity increase
Solution Approach 1:
The fairing is divided into modular sections that can be independently assembled and attached to different segments of the lead-in cable. This segmentation enables rapid installation by allowing workers to attach individual fairing sections along the cable length without requiring complete cable retrieval or complex assembly procedures.
Solution Approach 2:
Fairing sections are pre-assembled and pre-positioned on land or on the vessel deck before cable deployment. This preliminary preparation eliminates time-consuming in-water assembly operations and allows for quick attachment to the lead-in cable, reducing overall installation time while maintaining protection reliability.
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 fairings significantly reduce drag and vortex-induced vibrations, enhancing the operational efficiency of marine survey systems by minimizing the impact of lead-in cables on towing forces and stability.
Implementation Method 1
lead-in cables themselves contribute to drag, and are subject to 'strumming' caused by vortex shedding as the cable moves through the water
Implementation Method 2
lead-in cables themselves contribute to drag
Data Source
AI summary
A marine fairing. At least some of the illustrative embodiments are methods of installing a fairing on a line. In installing may include: wrapping a flap portion of the fairing at least partially around the line; and coupling an appendage defined by the fairing into a hollow defined by the fairing such that a distal portion of flap abuts a body portion of the fairing.