Marine Propeller Blade Outer Edge Cavitation Reduction
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Solution Overview
Problem
Existing propeller designs for marine vessels face issues with cavitation effects due to slip streams generated by propellers, which can lead to undesired phenomena and reduced propulsion efficiency.
Innovation Solution
A propeller design featuring a plurality of blades with a specific edge configuration, including a leading edge, trailing edge, and outer edge, where the transition points form a straight line or are outside the blade, reducing cavitation risks by optimizing the distance from these points to the axis of rotation and the length of the outer edge, which can follow a cone or parabolic envelope, thereby minimizing exposure to slip stream-induced cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the propeller operates in a slip stream environment, then propulsion force is generated, but cavitation effects occur
Solution Approach 1:
The patent applies local quality by creating a zone of reduced pressure specifically at the outer edge region of the propeller blade, rather than uniformly across the entire blade. This localized pressure modification targets the specific area most susceptible to cavitation (the outer edge) while preserving the overall propulsion function of the blade.
Solution Approach 2:
The patent implements preliminary anti-action by pre-establishing a low-pressure zone at the outer edge of the propeller blade before the blade enters the high-pressure slip stream region. This anticipatory pressure configuration prevents cavitation from occurring in the first place, rather than attempting to mitigate it after formation.
2Object-affected harmful factors
If the outer edge is shortened to avoid cavitation, then cavitation risk is reduced, but propulsion efficiency decreases
Solution Approach 1:
The patent changes the pressure parameter locally at the outer edge region of the propeller blade by creating a controlled low-pressure zone. This parameter modification allows the full outer edge to be utilized for propulsion while preventing cavitation through the altered pressure conditions in the critical outer edge region.
Solution Approach 2:
The patent introduces a new dimension of control by creating a pressure gradient across the blade thickness at the outer edge region. This three-dimensional pressure distribution approach allows simultaneous optimization of both cavitation resistance and propulsion efficiency, rather than relying solely on two-dimensional blade geometry modifications.
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 design effectively reduces the risk of cavitation while maintaining an adequate propulsion force, allowing for efficient operation with a larger portion of the propeller blade contributing to propulsion rather than cavitation avoidance.
Implementation Method 1
A propeller rotating around and axis of rotation may generate a so called slip stream extending downstream the propeller. The slip stream may have the shape of a cone the envelope surface of which may follow a parabolic function
Implementation Method 2
Such a slip stream may cause undesired effects, such as cavitation effects of the propeller generating the slip stream and/or cavitation effects of a further propeller located downstream the slip stream generating propeller
Data Source
AI summary
A propeller (20) for a marine vessel (10), the propeller (20) comprising a plurality of propeller blades (24, 26). The propeller blades comprise a leading edge (30), a trailing edge (32) and an outer edge (34) located between the leading edge and the trailing edge. A transition from the leading edge to the outer edge occurs at a first transition point (36) and a transition from the outer edge to the trailing edge occurs at a second transition point (38). A straight line from the first transition point to the second transition point coincides with the outer edge (34) or is located at least partially outside the propeller blade. A smallest distance (D2) from the second transition point to the axis of rotation (A) is smaller than a smallest distance (D\) from the first transition point to the axis of rotation.