Angled Stern Bulb Protrusion for Marine Propulsion Flow Rotation
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Solution Overview
Problem
Existing propeller designs face inefficiencies due to water flow velocity and distribution issues, leading to reduced thrust and increased vibrations, with previous solutions like fins and counter-rotating propellers being ineffective or prone to mechanical failure.
Innovation Solution
A propulsion system featuring at least two propellers with bulbus protrusions extending from the hull, angled to create a pressure gradient that rotates water flow counter to the propeller's rotation, enhancing efficiency and thrust while minimizing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fins are fitted to the hull forward of the propeller to rotate the flow, then propeller efficiency and thrust increase, but the solution is limited in effectiveness and adds device complexity
Solution Approach 1:
The invention extracts the flow rotation function from separate fins and integrates it directly into the propeller support structure. The bulbus protrusion with its angled leading portion inherently creates the necessary flow rotation without requiring additional fin components, thereby reducing device complexity while maintaining propeller efficiency improvement.
Solution Approach 2:
The invention merges the flow rotation function with the propeller support structure. The bulbus protrusion serves dual purposes: supporting the propeller and simultaneously rotating the water flow counter to the propeller rotation. This consolidation eliminates the need for separate fin components and reduces overall system complexity.
2Productivity
If counter-rotating propellers are used to rotate the flow, then propeller efficiency and thrust increase, but the system becomes complex and prone to mechanical failure
Solution Approach 1:
The invention extracts the flow rotation function from the propeller assembly itself and places it in the support structure. By having the bulbus protrusion create the flow rotation rather than requiring counter-rotating propellers, the system eliminates the mechanical complexity and reliability issues associated with dual propeller rotation mechanisms.
Solution Approach 2:
The bulbus protrusion acts as an intermediary element that creates the flow rotation without requiring the propeller itself to rotate counter to the flow. This intermediary structure simplifies the overall system by eliminating the need for complex counter-rotating propeller mechanisms while still achieving the desired flow rotation effect.
3Shape
If obstructions like struts or skegs are used to support the shaft, then the shaft can be enclosed in a tapered stern or stern bulb, but these obstructions locally slow down velocity and produce vibrations
Solution Approach 1:
The invention uses an asymmetric leading portion on the bulbus protrusion that is angled away from the centerline. This asymmetric geometry creates a pressure gradient that rotates the flow counter to the propeller rotation, thereby reducing vibrations while maintaining the enclosed shaft arrangement and stern bulb shape.
Solution Approach 2:
The invention changes the geometric parameters of the protrusion by angling the leading portion away from the centerline. This parameter change creates the necessary pressure gradient and flow rotation to reduce vibrations, while still allowing the shaft to be enclosed in the tapered stern bulb structure.
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 angled protrusions increase propeller efficiency and thrust by rotating water flow, reducing vibrations and optimizing power delivery, offering a more stable and efficient propulsion system compared to previous solutions.
Implementation Method 1
The leading portion is angled away from the centerline of the hull... create a pressure gradient that rotates water flow counter to the propeller's rotation
Data Source
AI summary
In a marine vessel, a propulsion system comprises at least one propeller having a direction of rotation about a drive shaft and a bulbus protrusion extending from the hull associated with each of the at least one propeller, each protrusion extending from the hull of the vessel, each protrusion receiving and rotatably supporting the at least one propeller. Each protrusion extends between leading and trailing ends and has a substantially circular cross section along a length between the leading and trailing ends having and a leading portion extending from the leading end wherein the leading portion is angled away from the centerline of the hull.