Ship Propulsion Duct with Curvature Optimization to Reduce Hub Vortices
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Solution Overview
Problem
Existing vessel propulsion systems, such as azimuth thrusters, face inefficiencies due to vortices formed around the hub, which reduce propulsive efficiency and maneuverability, especially in bollard conditions where precise positioning and towing are required.
Innovation Solution
A vessel propulsion apparatus featuring a duct with optimized sectional shapes and angles, including a convex outer surface at the front and concave at the rear, and an inner surface with specific parallel, front, and rear portions to improve flow dynamics, combined with main and sub-blades to reduce vortices and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard airfoil duct shape is used, then the structure is simple and easy to manufacture, but vortices form around the hub reducing propulsive efficiency
Solution Approach 1:
The duct cross-section is designed with different curvature characteristics at different locations: the front portion has a first curvature radius while the rear portion has a second curvature radius that is 0.05 to 0.15 times the first curvature radius. This local variation in geometric quality optimizes flow characteristics at each section, reducing vortex formation at the hub while maintaining manufacturability through defined geometric parameters.
Solution Approach 2:
The invention changes the geometric parameters of the duct cross-section, specifically the curvature radius ratio between front and rear portions (0.05 to 0.15 times). This parameter optimization modifies the flow field characteristics to reduce vortex intensity around the hub, thereby improving propulsive efficiency without compromising manufacturing feasibility.
2Productivity
If the duct cross-section is optimized to reduce vortices, then propulsive efficiency improves, but the design complexity increases
Solution Approach 1:
The duct cross-section is designed with different curvature characteristics at different locations: the front portion has a first curvature radius while the rear portion has a second curvature radius that is 0.05 to 0.15 times the first curvature radius. This local variation in geometric quality optimizes flow characteristics at each section, reducing vortex formation at the hub while maintaining manufacturability through defined geometric parameters.
Solution Approach 2:
The invention applies curvature optimization by defining specific radius ratios between different sections of the duct cross-section. The front portion and rear portion have deliberately different curvature radii, creating an optimized flow path that reduces vortex formation. This curvature-based design achieves complex flow control through relatively simple geometric definitions.
3Force
If a larger duct cross-sectional area is used, then thrust generation improves, but torque and energy consumption increase
Solution Approach 1:
The invention changes the geometric parameters of the duct cross-section, specifically the curvature radius ratio between front and rear portions (0.05 to 0.15 times). This parameter optimization modifies the flow field characteristics to reduce vortex formation, thereby improving thrust generation efficiency while reducing the torque and energy required to achieve the same thrust output.
Solution Approach 2:
The invention converts the potentially harmful vortex formation into a beneficial flow pattern. By optimizing the curvature radius ratio, the design transforms what would be energy-wasting vortices into controlled flow structures that actually enhance thrust generation while reducing overall energy consumption and torque requirements.
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
Enhances propulsive efficiency by optimizing thrust and reducing vortices, improving vessel operation and towing performance, particularly in bollard conditions, while minimizing torque and enhancing thrust generation.
Implementation Method 1
a duct having a nose as a front vertex of an airfoil section, and a tail as a rear vertex of the airfoil section
Implementation Method 2
the sectional shape of the duct includes: an outer surface formed convex upward at the front end of the duct, and formed concave downward at the back end of the duct; and an inner surface having an inner front portion of the duct formed convex downward at the front end of the duct, an inner rear portion of the duct formed convex downward at the back end of the duct, and a parallel portion seamlessly connecting the inner front portion of the duct with the inner rear portion of the duct
Data Source
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AI summary
A propulsion device for a ship is introduced. The propulsion device for the ship comprises a duct having a nose corresponding to the front vertex of a hydrofoil cross-section and a tail corresponding to the rear vertex of the hydrofoil cross-section, wherein the shape of the duct cross-section comprises: an outer surface formed upward in a convex shape at the front end of the duct and formed downward in a concave shape at the rear end of the duct; an inner front part of the duct formed downward in a convex shape at the front end of the duct; an inner rear part of the duct formed downward in a convex shape at the rear end of the duct; and a parallel part for connecting the inner forward part and the inner backward part in parallel to each other.