Hinged Fairing Sections for Towing Cable Twist Prevention
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Solution Overview
Problem
Streamlined cables used for towing submersible objects, such as variable depth sonars, often suffer from damage due to double twisting during the winding process, leading to system unavailability and potential damage to the winch or guide device.
Innovation Solution
A streamlined elongated element with fairing sections that are hinged and linked via individual coupling devices, allowing for relative rotation and angular stiffness adjustment to prevent complete twists, and a guide device with a concave pulley groove to facilitate hull orientation and reduce torsional stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the fairing is made rigid to reduce hydrodynamic drag at high speeds, then the cable can withstand high towing speeds of at least 20 knots, but the fairing becomes susceptible to crushing and damage when passing through guidance devices during winding
Solution Approach 1:
The fairing is divided into multiple modular sections that can rotate independently around the cable axis. Each section contains multiple hulls that are articulated to allow relative rotation, enabling the fairing to flex and adapt to guidance device geometries during winding operations while maintaining rigid hull structures for hydrodynamic efficiency at high towing speeds.
Solution Approach 2:
The fairing transitions from a static rigid structure to a dynamic articulated system where hulls can rotate relative to each other around the cable axis. This dynamic capability allows the fairing to accommodate the curvature and orientation changes required when passing through guidance devices during cable deployment and recovery operations.
2Ease of operation
If the hulls are linked axially and rotationally to maintain orientation, then the fairing can pass through guide elements smoothly, but the rotation of one hull causes rotation of neighbors and accumulates torsional stress leading to double twisting
Solution Approach 1:
The fairing is segmented into multiple independent sections along the cable axis, with each section containing articulated hulls. The segmentation allows each section to rotate independently, preventing the accumulation of torsional stress that would occur in a continuously linked rigid structure, while still enabling smooth passage through guide elements.
Solution Approach 2:
Different parts of the fairing have different rotational characteristics. The hulls within each section are articulated to allow relative rotation, while the sections themselves are linked axially. This local differentiation enables smooth guide element passage at the hull level while limiting torsional stress accumulation at the section level.
3Adaptability or versatility
If the fairing sections are free to rotate around the cable, then the hulls can orient themselves correctly relative to the water flow, but the fairing cannot maintain a predefined orientation relative to the winch drum during winding
Solution Approach 1:
The fairing employs a dynamic articulated mechanism where hulls can rotate relative to each other and to the cable axis. This dynamic structure allows hulls to naturally orient themselves perpendicular to the water flow during towing while still maintaining a predefined orientation relative to the winch drum during winding operations through the articulated connection mechanism.
Solution Approach 2:
The fairing's orientation parameters change dynamically based on operational conditions. During high-speed towing, the hulls rotate to orient perpendicular to the flow for optimal hydrodynamics. During winding operations, the articulated connections maintain a predefined orientation relative to the winch drum, demonstrating parameter adaptation to different operational states.
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 solution effectively minimizes the risk of double twisting, reducing damage to the fairing and maintaining system functionality by allowing controlled orientation and rotation of the fairing sections during winding and unwinding.
Implementation Method 1
said fairings being profiled so as to reduce the hydrodynamic drag of the at least partially submerged elongate object
Implementation Method 2
said fairing sections being free to rotate around the channel relative to each other
Data Source
Figure 1A~1D
Figure 2~4b
Figure 3
AI summary
A fairing intended for fairing an elongate object intended to be at least partially submerged, the fairing comprising a plurality of fairing sections (12), each fairing section (12) comprising a plurality of fairing elements (13), the fairing elements comprising a channel intended to receive the elongate object and being profiled in such a way as to reduce the hydrodynamic drag of the elongate object that is at least partially submerged, said fairing elements (13) being intended to be mounted pivoting on the elongate element about the longitudinal axis of the channel, said fairing elements (13) being linked together along the axis of the channel and being hinged to each other, the fairing sections (12) being free in rotation around the channel relative to each other.