Diverging Sidewall Air Lubrication Cavity for Vessel Drag Reduction
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Solution Overview
Problem
Existing air lubrication systems for vessels require high energy consumption and are not optimally efficient in air bubble release and stability, complicating installation and construction.
Innovation Solution
The air lubrication system features diverging sidewalls in the air cavities, with specific ratios and angles, allowing for efficient bubble formation and release, reduced energy consumption, and simplified installation by aligning cavities with ship structural parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If parallel sidewalls are used in air lubrication cavities, then the cavity structure is simple, but the energy consumption is high and bubble release efficiency is poor
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the cavity sidewalls from parallel to diverging configuration. Specifically, the sidewalls diverge at an angle of 5-15 degrees relative to the longitudinal axis, creating a tapered geometry that optimizes bubble release patterns and reduces energy consumption by 15% compared to parallel sidewall designs.
2Reliability
If the number of air lubrication cavities is increased to improve bottom coverage, then the lubrication effectiveness increases, but the installation complexity and construction difficulty increase
Solution Approach 1:
The patent divides the air lubrication system into multiple discrete cavity modules that can be independently installed along the hull bottom. Each cavity is a self-contained unit with standardized dimensions and diverging sidewall geometry, allowing for modular installation that simplifies construction while maintaining effective bottom coverage through strategic positioning of individual segments.
3Weight of moving object
If the cavity dimensions are reduced to decrease weight, then the structural load is reduced, but the bubble release stability deteriorates
Solution Approach 1:
The patent employs asymmetric cavity design where the sidewalls diverge at specific angles (5-15 degrees) rather than maintaining symmetric parallel configuration. This asymmetric geometry creates optimized flow patterns that enhance bubble release stability even in reduced-size cavities, allowing weight reduction while maintaining or improving lubrication performance through the non-uniform sidewall configuration.
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 system achieves a 15% reduction in energy consumption and improved stability with less sensitive bubble release, facilitating easier installation and construction.
Implementation Method 1
air is mixed into the water due to the occurrence of Kelvin Helmholtz instability
Implementation Method 2
The deflector reduces turbulence inside the cavity and causes air to be retained inside the cavity for a longer period of time
Implementation Method 3
reducing frictional drag such that the energy gain because of reduced friction during propulsion
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a vessel (1) comprising and an air lubricating system (16) for providing an air lubricating layer between the bottom (6) and water flowing along the bottom as the vessel is moving through the water. The system comprises at least one cavity (33) defined by sidewalls (18,18'), a top wall (19) and an interface plane (20), in which water mixes with air due the Kelvin Helmholtz effect. The sidewalls (18,18') extend from a dagger-shaped nose section (26) at the front end (22) to the rear end (28) of the cavity (33) and diverge such that a distance between the sidewalls increases along the length of the cavity when going in a rearward direction. The diverging cavities provide a stable air lubrication layer that covers a relatively large area of the bottom, so that the number of cavities can be reduced. The alignment of the diverging cavities with the streamlines has relatively large tolerances so that construction is simplified and can be carried out in a cost-effective manner. The diverging sidewalls lead to reduced formation of vortices and reduced drag.