Follower Vessel Positioning in Time-Dependent Kelvin Wakes
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Solution Overview
Problem
Existing methods for reducing wave-making resistance in vessels operating in a seaway fail to account for the time-dependent changes in the Kelvin wake wave formation, leading to inefficiencies in positioning follower vessels to minimize resistance, especially when the lead vessel diverges from its linear path or changes speed.
Innovation Solution
A system and method that utilize a time-dependent approach to determine the propagation and position of Kelvin wake waves, allowing follower vessels to align with the optimal resistance reduction zones based on the lead vessel's past state, including changes in heading and speed, using computational fluid dynamics and wave theory to calculate the propagation of waves and position vessels for reduced wave-making resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If existing methods are used to position follower vessels based on current lead vessel state, then positioning is simple, but wave-making resistance reduction is ineffective when lead vessel changes direction or speed
Solution Approach 1:
The system performs preliminary calculations of the resistance reduction zone based on the lead vessel's past state (historical position, speed, and heading data). By pre-calculating where the Kelvin wake waves will be and positioning the follower vessel accordingly, the system achieves effective resistance reduction even when the lead vessel changes course or speed, without requiring complex real-time adjustments
Solution Approach 2:
The system dynamically adapts the positioning strategy by incorporating time-dependent factors. It calculates the resistance reduction zone based on the lead vessel's historical trajectory and predicts future wave positions, allowing the follower vessel to maintain optimal positioning despite changes in lead vessel motion, thus achieving both simplicity and effectiveness
2Measurement precision
If follower vessel positions are calculated based on lead vessel current state, then calculation is straightforward, but positioning accuracy deteriorates when lead vessel maneuvers
Solution Approach 1:
The system uses historical data from the lead vessel (past position, speed, and heading) to pre-calculate where the Kelvin wake waves will propagate to. By accounting for the time it takes for waves to form and propagate, the system determines the optimal position for the follower vessel in advance, ensuring accurate positioning even when the lead vessel maneuvers
Solution Approach 2:
The system implements a time-dependent calculation approach that dynamically adjusts the resistance reduction zone based on the lead vessel's historical trajectory and the propagation characteristics of Kelvin wake waves. This dynamic model compensates for the time delay between wave generation and wave arrival, maintaining high positioning accuracy throughout the seaway operating conditions
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 approach significantly reduces wave-making resistance across the entire speed regime and operational domain of vessels, resulting in lower propulsion power and fuel consumption by accurately accounting for variations in the lead vessel's trajectory and speed.
Implementation Method 1
In 1887, Lord Kelvin demonstrated that a wake pattern created by an object (e.g., vessels) moving at a uniform speed over a surface of water (e.g., the seaway) may always be delimited by an angle equal to arcsine 1/3=19.5 degrees. As such, the wake pattern produced by the vessels as they move across the surface of the seaway is known as a Kelvin wake.
Implementation Method 2
U.S. patent application Ser. No. 16/988,668 filed Mar. 18, 2021 by the present inventors disclosed one or more aspects of a system and method that reduces wave-making resistance of vessels, thereby resolving at least some of these problems associated with vessels.
Data Source
AI summary
A system and method that reduces wave-making resistance of at least one follower vessel following at least one lead vessel operating in a seaway based on a determination of time-dependent variations in the Kelvin wake waves being generated by the lead vessel when operating in a seaway. By using a time-dependent Kelvin wake wave generation approach, the determination of where to position the follower vessel in a reduced wave-making resistance region may be improved, such as when the lead vessel changes direction and/or speed in the seaway. Such an approach may position the follower vessel based on information associated with the Kelvin wake wave generated by the lead vessel in the past, which the follower vessel approaches this past-generated Kelvin wake wave and is positioned in the reduced wave-making resistance region associated with this past-generated Kelvin wake wave.