Underwater Cable Density Control via Pre-Compression
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Solution Overview
Problem
Underwater cables used as towing cables for antennas experience significant changes in density due to hydrostatic pressure, leading to buoyancy issues and vibrations, which affect the alignment and functionality of the towed antenna, making it difficult to detect noise sources accurately.
Innovation Solution
Manufacturing the cable core under pressures differing from ambient pressure to minimize air bubbles and control density changes, ensuring a maximum density variation of ±5.0%, thereby maintaining consistent buoyancy and preventing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the cable core is manufactured at ambient pressure, then the manufacturing process is simple, but the cable contains many air bubbles causing large density changes (up to 20%) when used underwater
Solution Approach 1:
The cable core is manufactured under pressure before deployment to pre-compress air bubbles and reduce their volume. This preliminary compression action ensures that when the cable is deployed underwater, the density change is minimized because the air bubbles have already been compressed during manufacturing, eliminating the need for them to expand later under water pressure.
Solution Approach 2:
The manufacturing process changes the pressure parameter from ambient pressure to elevated pressure (e.g., 5-20 bar). This parameter change allows air bubbles to be compressed during manufacturing, reducing their volume and thus minimizing the density change of the cable core when the cable is subsequently deployed underwater at various depths.
2Ease of operation
If the cable density changes significantly underwater, then the cable can be manufactured simply at ambient pressure, but the towed antenna cannot maintain straight alignment making sound source detection difficult
Solution Approach 1:
The cable core is pre-compressed during manufacturing to minimize air bubble volume before the cable is deployed. This preliminary compression ensures that when the cable is deployed underwater, the density change is minimal, allowing the towed antenna to maintain straight alignment without requiring complex buoyancy compensation systems.
Solution Approach 2:
By changing the pressure parameter during manufacturing, the air bubbles in the cable core are compressed, reducing the cable's overall density change when deployed underwater. This parameter change enables the towed antenna to maintain proper alignment without requiring additional buoyancy compensation devices.
3Reliability
If trim weights and hydrodynamic fins are added to compensate for buoyancy changes, then local buoyancy can be adjusted, but the cable still vibrates due to non-uniform density distribution
Solution Approach 1:
The manufacturing process applies pressure to compress air bubbles uniformly throughout the cable core, ensuring homogeneous density distribution. This eliminates the non-uniform density variations that cause vibrations, making additional stability devices unnecessary.
Solution Approach 2:
The cable core is manufactured under pressure to ensure uniform compression of air bubbles throughout its length, creating a homogeneous density distribution. This homogeneity prevents vibrations caused by non-uniform buoyancy forces, eliminating the need for additional stability devices like trim weights and hydrodynamic fins.
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 method ensures the towed antenna remains aligned and functional, allowing for precise detection and identification of noise sources without the need for post-use buoyancy corrections, reducing the risk of kinking and damage.
Implementation Method 1
at least the cable core is manufactured under a pressure which deviates from the ambient pressure, so that the cable core is produced with few air bubbles
Implementation Method 2
Underwater cables are compressed by hydrostatic water pressure when used underwater, causing the cable's volume to decrease and its density to increase
Data Source
Figure 1
AI summary
The invention relates to a method for manufacturing an underwater cable (101), in particular a trailing cable for a trailing antenna of a watercraft, wherein the underwater cable (101) has a cable core (110) and an outer sheath (108, 109), and at least the cable core (110) is manufactured under a pressure which deviates from ambient pressure such that the cable core (110) is manufactured free of air bubbles, and the underwater cable, which has been brought to a depth under water and subsequently brought back to the surface of the water, has at most a change in density of ± 5.0%, in particular ± 3.0% or ± 1.5%. The invention additionally relates to an underwater cable, a submarine cable, a towed array sonar, and a vehicle.