Buoyancy Control Compressibility Mismatch Underwater Vehicles
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Solution Overview
Problem
Underwater vehicles with buoyancy control systems face significant energy expenditure due to compressibility mismatch with seawater, leading to inefficient ascents and descents, as they are typically stiffer than the surrounding fluid, requiring complex and costly compensation systems like spring-backed pistons.
Innovation Solution
Incorporating a compressibility compensation system with flexible containers filled with highly compressible silicone liquids, such as polydimethylsiloxanes, to match the vehicle's compressibility with seawater, reducing the energy needed for buoyancy adjustments and thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If underwater vehicles are fabricated from solid materials to provide structural strength, then the vehicle structure is strong and stable, but the vehicle becomes stiffer than seawater and compresses approximately half as much as seawater, leading to compressibility mismatch and increased energy expenditure for buoyancy control
Solution Approach 1:
The patent changes the compressibility parameter of the vehicle by incorporating a compressible fluid (such as air or gas) into the buoyancy control system. This allows the vehicle to match the compressibility of seawater, reducing the energy required for buoyancy control while maintaining structural strength through the rigid pressure hull.
2Use of energy by moving object
If a spring-backed piston system with neutrally compressible float is used to compensate for compressibility mismatch, then the vehicle can closely match overall vehicle compressibility to seawater, but the system becomes complex, expensive, and cumbersome
Solution Approach 1:
The patent extracts and eliminates the complex spring-backed piston mechanism, replacing it with a simpler compressible fluid system. The buoyancy control is achieved directly through the compressibility of the enclosed fluid, removing the need for mechanical springs, pistons, and neutrally compressible floats, thereby significantly reducing system complexity.
Solution Approach 2:
The patent uses a pneumatic approach by enclosing a compressible gas or air within the pressure hull to provide buoyancy control. The compressibility of the gas matches that of seawater, allowing passive compensization without complex mechanical systems. This pneumatic system replaces the hydraulic spring-backed piston mechanism.
3Adaptability or versatility
If buoyancy control systems are used to guide underwater vehicles to different depths, then the vehicles can perform research and monitoring tasks, but significant energy is expended to overcome water density differences induced by pressure when the vehicle is less compressible than water
Solution Approach 1:
The patent changes the compressibility parameter of the vehicle's buoyancy system to match seawater by using a compressible gas. This allows the vehicle to passively adapt to pressure changes during depth variations, maintaining neutral buoyancy without expending significant energy on active buoyancy control.
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
This solution significantly reduces the energy required for underwater vehicles to operate efficiently, allowing for longer missions and increased payload capacity by passively compensating for compressibility and thermal expansion mismatches, thereby enhancing operational efficiency and endurance.
Implementation Method 1
the range of seawater density variation due to a pressure change from the sea surface to the sea floor in the open, deep ocean (e.g., 5-6 km depth) is approximately 2-3%
Implementation Method 2
Buoyancy control systems can be used to guide these underwater vehicles to different depths and to maintain given depths within the respective ocean and/or lake
Implementation Method 3
systems and methods for compensating for compressibility and thermal expansion coefficient mismatch in buoyancy controlled underwater vehicles
Data Source
AI summary
Systems and methods for compensating for compressibility and thermal expansion coefficient mismatch in buoyancy controlled or buoyancy-driven underwater vehicles are disclosed herein. An underwater vehicle configured in accordance with one embodiment of the disclosure, for example, can include a hull and a compartment carried by the hull and at least partially flooded with a first liquid having similar properties as a surrounding liquid into which the hull is configured to be deployed. The first liquid has a first compressibility and thermal expansion coefficient. The underwater vehicle can further include a compressibility and thermal expansion coefficient compensation system comprising a container filled or at least partially filled with a compressible liquid comprising silicone in the compartment. The compressible liquid has a second compressibility higher than the first compressibility and second thermal expansion coefficient higher than the first thermal expansion coefficient. The compressible liquid can include, for example, hexamethyldisiloxane (HMDS).