Porous Sonar Casing Isolating Sensors from Turbulent Flow
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Solution Overview
Problem
Towed sonar systems face noise interference from turbulent water flow, which reduces their sensitivity and performance due to the detection of pressure fluctuations by acoustic sensors.
Innovation Solution
A casing for towable sonar apparatus comprising a tubular member with a porous outer layer and an open-cell foam or mesh structure that traps a layer of still water around the sensors, creating a stand-off from turbulent flow and reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sonar apparatus is towed through water, then the sonar system can be deployed and operated, but turbulent water flow creates noise that reduces sensitivity
Solution Approach 1:
A casing is introduced as an intermediary component between the turbulent water flow and the acoustic sensors. The casing includes a tubular member with porous outer layer and open-cell foam or mesh structure that mediates the interaction by allowing water passage while maintaining a protected internal environment for the sensors.
Solution Approach 2:
The tubular member of the casing is designed as a flexible structure that can be radially contracted for storage and expanded for operation. This flexible shell approach allows the casing to adapt to deployment conditions while maintaining its noise-reducing function throughout the operational lifecycle.
2Strength
If a traditional solid casing is used, then sensors are protected from water, but noise from turbulent flow is not reduced and sensors remain susceptible to biofouling
Solution Approach 1:
The casing employs porous materials including a porous outer layer and open-cell foam structure that allow water to pass through while providing acoustic isolation. The porous structure enables water flow through the casing walls, preventing pressure buildup and reducing the turbulent boundary layer effect on internal sensors.
Solution Approach 2:
The casing is constructed as a composite structure combining multiple materials with different properties: a porous outer layer for water permeability, open-cell foam for acoustic damping, and potentially anti-biofouling coatings. This composite approach addresses multiple harmful factors simultaneously while maintaining sensor protection.
3Duration of action of moving object
If the sonar apparatus operates for extended periods, then data collection is improved, but biofouling increases noise and reduces performance
Solution Approach 1:
The porous casing structure provides self-service anti-biofouling functionality by allowing continuous water flow through the walls, which prevents stagnant water conditions that promote biofouling. The design inherently resists biofouling accumulation without requiring active cleaning systems or chemical treatments.
4Strength
If a rigid casing is used, then structural strength is maintained, but the apparatus cannot be efficiently stored or deployed
Solution Approach 1:
The casing transitions from a static rigid structure to a dynamic flexible structure that can change its configuration. The tubular member can be radially contracted to a compact form for efficient storage and transport, then expanded to its operational form for deployment, maintaining structural integrity throughout the transformation cycle.
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 reduces noise generated by turbulent water flow, enhancing the sensitivity and performance of towed sonar systems by isolating sensors from the turbulent boundary layer and preventing biofouling, while allowing for collapsible and expandable designs for efficient storage and deployment.
Implementation Method 1
the tubular member comprises a porous outer layer and an open-cell foam or mesh structure that traps a layer of still water around the sensors
Data Source
Figure 1a
Figure 1b
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AI summary
There is provided a casing for a towable sonar apparatus, comprising: a tubular member, wherein the tubular member comprises a foam member or a mesh member; a first layer around the tubular member, wherein the first layer is porous.