Collapsible Propeller with Shielding Shell for Drag Reduction
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Solution Overview
Problem
Existing multiple propulsion systems for vessels, such as boats and ships, face significant drag issues when not in use, as the propeller creates hydrodynamic resistance, which is not fully mitigated by existing collapsible or retractable solutions, particularly on larger vessels.
Innovation Solution
A collapsible propeller mechanism that fully encases the blades within a shell when not in use, minimizing drag by using a shielding shell and a mechanism to fold and unfold the blades seamlessly, allowing for minimal hydrodynamic forces when the propeller is inactive, and integrating this with the drive system for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the propeller is left in a stationary position, then the propulsion system is ready for immediate use, but a large amount of turbulence and hydrodynamic drag is created around the propeller
Solution Approach 1:
The propeller blades are designed to rotate about axes parallel to the propeller shaft axis, transitioning between an unfolded propulsion position and a folded storage position. This dynamic reconfiguration allows the propeller to minimize hydrodynamic drag when not in use while maintaining readiness for immediate propulsion when unfolded.
Solution Approach 2:
The propeller is divided into multiple blades that can independently rotate about axes parallel to the shaft axis. This segmentation allows each blade to be folded back against the shaft when not in use, reducing the overall swept area and hydrodynamic resistance while maintaining structural integrity.
2Object-generated harmful factors
If foldable propellers are used to minimize drag, then hydrodynamic resistance is reduced, but the mechanism requires higher minimum output from the propulsion system to unfold the blades
Solution Approach 1:
Instead of using centrifugal force from propeller rotation to unfold the blades (which requires high minimum power), the design inverts the approach by using a mechanical linkage system that can fold and unfold the blades with minimal power input. The linkage mechanism translates small rotational movements into the larger blade deployment motion, reducing the power threshold required.
3Object-generated harmful factors
If the propeller blades are folded parallel to the drive shaft, then the swept area is reduced, but the propeller still drags through the water creating residual drag
Solution Approach 1:
The propeller blades are designed to nest against the propeller shaft when folded, with each blade rotating parallel to the shaft axis. This nesting configuration minimizes the protruding volume and surface area that interacts with water, reducing residual drag to the absolute minimum while maintaining the ability to rapidly deploy for propulsion.
4Object-generated harmful factors
If retractable devices are used to eliminate drag, then hydrodynamic resistance is minimized, but the devices are often used only for transverse thrust and require complex retraction mechanisms
Solution Approach 1:
The propeller design maintains universal functionality for forward propulsion while incorporating the ability to minimize drag when not in use. The blades can be unfolded for propulsion and folded parallel to the shaft for drag reduction, providing multi-functionality without requiring separate transverse thrust mechanisms or complex retraction systems.
Data Source
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AI summary
The present invention concerns a propelling unit for propelling a vessel through water, said propelling unit comprising: a rotor comprising a plurality, preferably two or more, foldable hydrodynamic blades, said rotor being mounted on a drive shaft connected to drive means for propelling said vessel by rotating said rotor around an axis, a shielding shield shiftable between a first and second position, wherein the shielding shield in said first position is adapted to cover and to accommodate the rotor with the blades in their retracted position, and wherein the shielding shield in the second position allows for the blades to be extracted, wherein an extraction mechanism is provided for performing said shifting between the first and second positions.