Drag-Reducing Moonpool Separator Plate for Sloshing Control
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Solution Overview
Problem
Existing moonpool designs in offshore vessels lead to increased fuel consumption due to intense water sloshing, which current drag reduction measures fail to accurately address, and ship model tests are limited by scale effects and high costs.
Innovation Solution
A drag-reducing separator plate with a straight upper wall and baffle lower part, designed to match the moonpool's rear wall, changes water sloshing mode to vertical piston oscillation, reducing momentum exchange and incorporating movable features for optimal positioning during navigation and station keeping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the moonpool opening is enlarged to improve operational efficiency, then the moonpool can accommodate larger equipment and improve working capacity, but the water sloshing amplitude increases and additional drag increases significantly
Solution Approach 1:
The invention divides the moonpool space into multiple compartments using separator plates. This segmentation prevents water sloshing across the entire moonpool opening, effectively reducing the sloshing amplitude and momentum exchange while maintaining the large opening size needed for operational efficiency.
Solution Approach 2:
The separator plates act as intermediary structures between the external fluid and the moonpool interior. These plates restrict momentum exchange by providing physical barriers that break up the flow patterns, thereby reducing the harmful drag forces while allowing the moonpool to maintain its large dimensions.
2Object-affected harmful factors
If traditional drag reducing devices like flanges and damping chambers are used, then some drag reduction effect is achieved, but the design requires extensive ship model testing which is time-consuming, expensive, and subject to scale effects
Solution Approach 1:
The invention uses numerical simulation to create virtual models of the separator plates and their interaction with water. This allows for accurate prediction of drag reduction effects without requiring physical ship model tests, thereby eliminating the time loss and costs associated with extensive model testing while still achieving reliable drag reduction.
Solution Approach 2:
The invention replaces the mechanical ship model testing system with a numerical simulation system. By using computational fluid dynamics and other numerical methods, the design process eliminates the need for physical models and water tank tests, significantly reducing design time and costs while maintaining accuracy.
3Object-affected harmful factors
If separator plates are positioned to maximize drag reduction during navigation, then momentum exchange is reduced effectively, but the separator plates may interfere with station keeping operations
Solution Approach 1:
The separator plates are designed to be movable rather than fixed, allowing them to change position based on operational requirements. During navigation, they are positioned to maximize drag reduction by restricting momentum exchange. During station keeping operations, they can be repositioned or removed to avoid interfering with operational activities, thus maintaining ease of operation.
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
Significantly reduces drag by interleaving and subtracting additional drag forces through opposite phase oscillations, enhancing barrier effects and minimizing momentum exchange, while maintaining operational convenience.
Implementation Method 1
change the sloshing mode of the water in the moonpool to reduce the momentum exchange between the water inside and that outside the moonpool and achieve drag reduction
Implementation Method 2
Significantly reduces drag by interleaving and subtracting additional drag forces through opposite phase oscillations
Data Source
AI summary
A drag-reducing separator plate for a moonpool, wherein the upper part thereof is a straight wall perpendicular to the sea level, the lower part thereof is connected to a baffle, and a connecting portion is connected between the straight wall and the baffle. The connecting portion may be in the shape of an arc. The shape of the drag-reducing separator plate matches that of the rear wall of the moonpool. During navigation, the drag-reducing separator plate is located in the middle or front of the moonpool, and can cooperate with a drag-reducing notch on the rear wall of the moonpool to greatly reduce the drag induced by intense sloshing of water in the moonpool during navigation of an offshore vessel. When offshore operations are performed under a station keeping condition, the drag-reducing separator plate is moved to the rear wall of the moonpool to avoid hindering the offshore operations.