Curved Blade Flange Screw Propeller for Ice-Going Pod Drive
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Solution Overview
Problem
Existing screw propellers for ice-going vessels face challenges in withstanding lateral ice interactions and fragment impacts, leading to increased complexity, manufacturing costs, and difficulty in repairing damaged blades, which complicates the design and operation of pod drives.
Innovation Solution
The screw propeller design features a blade flange with a curved generatrix in the meridional cross-section, reducing the distance from the blade foil's weakest section to the propeller axis, thereby increasing the moment arm of the blade failure load and lowering the overall blade failure load, while maintaining strength and compliance with shipping regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the screw propeller is designed with conventional blade flange geometry, then the structure is simpler and manufacturing is easier, but the blade failure load is higher and transfers more ice loads to other components
Solution Approach 1:
The blade flange is designed with a curved generatrix in the meridional cross-section instead of a straight line, creating a spherical or curved surface geometry. This curvature reduces the distance from the blade foil's weakest section to the propeller axis, thereby reducing the moment arm of ice loads and lowering the blade failure load transferred to other components.
2Force
If the distance from the blade foil's weakest section to the propeller axis is reduced, then the moment arm of blade failure load is reduced and component loads are minimized, but the blade flange geometry becomes more complex
Solution Approach 1:
The blade flange employs a curved generatrix that creates a spherical or curved surface, strategically positioning the weakest section of the blade foil closer to the propeller axis. This geometric configuration reduces the moment arm distance, thereby minimizing the force transmission to other components during blade failure.
3Weight of moving object
If conventional straight generatrix is used for blade flange, then manufacturing is easier and cost is lower, but weight and cost of pod drive increase due to higher loads on components
Solution Approach 1:
The curved generatrix of the blade flange creates a spherical or curved surface geometry that reduces the moment arm of ice loads. This design reduction in blade failure load and the subsequent reduction in component loads and overall pod drive weight.
Data Source
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AI summary
The invention relates to the field of shipbuilding and more specifically to the screw propeller for a pod drive of a vessel, particularly an ice-going vessel, providing movement both ahead and astern in icy conditions where the ice is traversable, while also providing steering for the vessel, and to a pod drive comprising said screw propeller. To reduce the weight, and consequently the cost, of the pod drive, the screw propeller comprises a propeller hub, made so that it can be rigidly attached to the conical tailpiece of the propeller shaft, and screw propeller blades, each comprising a blade foil and a blade flange made in one piece, mounted on the propeller hub. The blade foil passes into the blade flange via a fillet joint forming the weakest portion for the possible destruction of the blade in the cross section of its foil, located immediately adjacent to the fillet joint. The outer surface of the blade flange has a profile, in its meridional cross section, curved inwards towards to the propeller axis, to reduce the distance from said blade foil cross section to the propeller axis.