Pre-swirl Stator Span Variation for Propulsion Efficiency
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Solution Overview
Problem
Existing propulsion systems face challenges in enhancing propulsion efficiency while minimizing resistance and cavitation around pre-swirl stators, which affects the performance of vessels.
Innovation Solution
The proposed solution involves a propulsion efficiency enhancing apparatus with pre-swirl stators arranged radially around the propeller, where the span lengths and installation angles of the stators are varied to reduce resistance and cavitation, and winglets or additional members are formed at the tip portions to further mitigate cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pre-swirl stators are used to enhance propulsion efficiency, then the propulsion efficiency of the propeller is improved, but the resistance performance of the vessel deteriorates
Solution Approach 1:
The patent applies local quality by varying the span lengths of different pre-swirl stators arranged radially around the propeller. Each stator has a different span length optimized for its specific radial position, allowing the system to enhance propulsion efficiency while minimizing resistance. The span length of each stator is specifically designed based on its location to optimize local flow conditions.
2Productivity
If pre-swirl stators are used to generate swirling flow, then the propulsion efficiency is enhanced, but cavitation is generated around the tip portions of the stators
Solution Approach 1:
The patent addresses cavitation by implementing local quality modifications at the tip portions of the pre-swirl stators. Winglets or additional members are formed specifically at the tip portions where cavitation occurs, while the main body of the stators maintains their original configuration for efficient swirling flow generation. This localized modification reduces cavitation without compromising overall propulsion efficiency.
Solution Approach 2:
The patent converts the harmful cavitation effect into a beneficial outcome by designing winglets or additional members at the stator tip portions. These modifications transform the high-velocity flow conditions that cause cavitation into controlled flow patterns that reduce cavitation damage while maintaining or even enhancing the swirling flow generation capability.
3Device complexity
If uniform span lengths are used for all pre-swirl stators, then the structure is simple, but resistance and cavitation cannot be optimized
Solution Approach 1:
The patent implements local quality by assigning different span lengths to different pre-swirl stators based on their radial positions. This non-uniform configuration optimizes the flow conditions at each location, reducing resistance and cavitation. The complexity increase is minimal and only affects the geometric parameters of the stators, while the overall system structure remains relatively simple.
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
This configuration effectively reduces resistance and cavitation, enhancing propulsion efficiency by optimizing the flow patterns and minimizing the impact of cavitation on the propeller.
Implementation Method 1
the pre-swirl stators make, when a propeller rotates to move the vessel forward, the flow of water around the stern bent in the opposite direction of the rotation direction of the propeller so that the water can flow to the propeller. At this time, swirling flow generated by the pre-swirl stators is absorbed by the propeller
Implementation Method 2
the pitch angles of the tip portions of the pre-swirl stators are smaller than those of the remaining portions, an angle of attack with respect to inflow entering the tip portions can become relatively small so as to reduce cavitation generated around the tip portions
Data Source
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AI summary
A propelling efficiency enhancing device is disclosed. A propelling efficiency enhancing device according to an embodiment of the present invention is disposed in front of a propeller and includes current fixing blades disposed radially around the rotating shaft of the propeller. The current fixing blades are positioned at regions, from among the left region and right region of the surface of revolution of the propeller, at which the propeller rotates upward, the span length of at least one of the current fixing blades is different from those of the others, and the span length of an arbitrarily selected current fixing blade from among the current fixing blades is greater than or equal to that of another current fixing blade disposed directly thereunder.