Bow Hydrodynamic Duct for Vessel Resistance Reduction
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Solution Overview
Problem
Existing vessel designs face challenges in reducing wave making and frictional resistances, leading to increased fuel consumption, as previous attempts at hydrodynamic ducts either failed to optimize flow differentiation or required additional energy inputs, resulting in unfavorable cost-benefit ratios.
Innovation Solution
A hydrodynamic duct is designed with optimized horizontal and lateral wall portions, featuring airfoil sections, acute angles, or curved configurations, strategically positioned to contain wave-making and frictional pressures, with Centers of Low Pressure aligned to enhance flow speed and reduce resistance, allowing for improved wave making and frictional resistance reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a bulb or ball-shaped stem section is used, then wave-making resistance is reduced, but the frontal surface area remains extensive leading to increased frictional resistance and fuel consumption
Solution Approach 1:
The invention segments the frontal surface by introducing a duct structure that divides the water flow into two distinct paths: flow through the duct and flow around the duct. This segmentation allows the bow to interact with water in a controlled manner, reducing the effective frontal surface area that generates resistance while maintaining the protective function of the bulb.
Solution Approach 2:
The duct acts as an intermediary structure between the bulb and the surrounding water. It mediates the interaction by providing a controlled flow path that differentiates the water flow characteristics, allowing the bow to cut through water more efficiently while reducing both wave-making and frictional resistances.
2Object-affected harmful factors
If a wave-making energy absorbing duct is mounted at the bow, then wave generation is reduced, but flow differentiation between duct and surrounding water is inadequate
Solution Approach 1:
The invention applies local quality by creating distinctly different flow conditions in different locations: laminar, controlled flow through the duct versus turbulent flow around the duct. The duct interior is designed with smooth surfaces and optimized geometry to maintain laminar flow, while the exterior allows natural turbulent flow, creating a localized quality difference that enhances flow differentiation.
Solution Approach 2:
The invention changes flow parameters within the duct by controlling viscosity effects, pressure distribution, and flow velocity profiles. The duct geometry is optimized to maintain laminar flow conditions (low Reynolds number flow) inside the duct while allowing turbulent flow outside, creating a parameter difference that improves flow differentiation and reduces resistance.
3Reliability
If mobile portions are included in the duct design, then flow management is improved, but additional energy from the engine is required resulting in unacceptable cost-benefit ratio
Solution Approach 1:
The duct is designed as a fixed, passive structure that self-regulates water flow without requiring active control mechanisms. The geometry and positioning of the duct automatically create the desired flow differentiation as the vessel moves through water, eliminating the need for mobile portions or active energy input while maintaining effective flow management.
4Object-affected harmful factors
If the duct extends above and below the waterline, then wave making resistance is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The duct incorporates curved, streamlined surfaces that follow hydrodynamic principles. The airfoil-like cross-section and curved transitions reduce flow separation and turbulence, allowing the duct to extend above and below the waterline while maintaining structural efficiency and reducing manufacturing complexity compared to angular or flat-sided designs.
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 duct effectively reduces wave making and frictional resistances, resulting in lower fuel consumption and improved vessel performance, as demonstrated by towing tank tests across various speeds and vessel types, with economic and environmental benefits.
Implementation Method 1
the Centers of Low Pressure of the lateral wall portions (2, 3) in the region of connection thereof with the horizontal wall portion (1) being located in a selected position between the Center of Low Pressure and up to or slightly forwardly the leading edge of the horizontal wall portion (1)
Implementation Method 2
Wave making and frictional resistances constitute important parameters that determine fuel consumption during cruising of a vessel
Implementation Method 3
Wave making and frictional resistances constitute important parameters that determine fuel consumption during cruising of a vessel
Data Source
AI summary
Hydrodynamic duct mounted at the bow of a vessel, comprising a horizontal wall portion (1) and two lateral wall portions (2,3), whereby the flow through the duct acquires substantially different characteristics from the flow outside it and thereby wave making and frictional resistances are reduced and the fuel conventionally required for the propulsion of the vessel is reduced accordingly. The duct is arranged with the Center of Low Pressure (1c) corresponding to a zero angle of attack onto the horizontal wall portion (1) being located in the region of generation of the first bow wave and with the Centers of Low Pressure (2c,3c) of the lateral wall portions (2,3) in the region of connection thereof with the horizontal wall portion (1) being located in a selected position between the Center of Low Pressure (1c) and up to or slightly forwardly the leading edge (la) of the horizontal wall portion (1).