Micro Bubble Generator for Ship Hull Drag Reduction
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Solution Overview
Problem
Existing methods for reducing frictional drag on vessels, such as winged air induction pipe systems and air bubble nozzles, either increase energy consumption or compromise cargo space, and fail to efficiently adapt to varying sea states.
Innovation Solution
A method involving a compressor-driven air cavity at the vessel's bottom, generating micro bubbles through a rippling water-air interface, which are distributed along the hull to reduce drag, while maintaining cargo space and adapting to different sea conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a winged air induction pipe system is used to generate micro bubbles, then frictional drag is reduced and energy savings of up to 15% are achieved, but the system requires specific low pressure region conditions and may not adapt well to varying sea states
Solution Approach 1:
The system dynamically adjusts bubble generation based on vessel speed and sea conditions. The compressor device modulates air supply pressure and flow rate in response to varying operational conditions, allowing the system to maintain effectiveness across different sea states while optimizing energy consumption.
Solution Approach 2:
The system changes physical parameters such as air pressure, bubble size distribution, and cavity pressurization level according to operational requirements. By varying these parameters, the system achieves both energy efficiency and adaptability to different sea states.
2Area of stationary object
If multiple air bubble generating nozzles are mounted on the hull with compressed air supply, then bubble coverage is improved, but energy consumption increases due to active air compression
Solution Approach 1:
The system uses a cavity pressurization approach where compressed air is introduced into an enclosed cavity rather than directly through multiple nozzles. This pneumatic approach creates a rippling water-air interface that naturally generates and distributes bubbles across the hull surface, reducing the energy required compared to direct nozzle compression while maintaining broad coverage.
3Productivity
If air is supplied at high pressure to empty the cavity of water, then bubble generation efficiency is improved, but the compressor energy consumption increases
Solution Approach 1:
The system applies partial pressurization to the cavity - enough to create the rippling interface and generate bubbles efficiently, but not excessive pressure that would waste energy. The pressurization is maintained at optimal levels to sustain bubble generation without over-compression.
Solution Approach 2:
The cavity pressurization is maintained continuously at an optimal level to sustain the rippling water-air interface and continuous bubble generation. This continuous action at moderate pressure levels is more energy-efficient than intermittent high-pressure cycles.
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 achieves energy savings of up to 15% in propulsion by generating small-sized bubbles that cover a large hull surface area, reducing frictional drag in a cost-effective and adaptable manner.
Implementation Method 1
providing air into the cavity via a compressor device at a pressure higher than atmospheric pressure to at least partially empty the cavity of water
Implementation Method 2
providing a rippling water-air interface in the cavity for forming a mixing region, generating a plurality of air bubbles in the mixing region
Data Source
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AI summary
The invention relates to a method of generating a layer of bubbles on a hull of a vessel comprising the steps of: -providing a cavity at the bottom of the vessel, having a length of at least 1 m and no longer than 30 % of the vessel length L along the bottom, preferably no longer than 25%, most preferably no longer than 10% of the vessel length L, and having a top surface spaced at least 50 cm away from the bottom plane, preferably at least 1 m away from the bottom plane, -providing air into the cavity via a compressor device at a pressure higher than atmospheric pressure to at least partially empty the cavity of water, -providing a water-air interface in the cavity for forming a mixing region, -generating a plurality of air bubbles in the mixing region, and -providing a bubble outlet at or near the rear of the cavity for allowing the bubbles to flow out along the hull towards the rear of the vessel.