Ship Propulsion Unit Vertical Tilt Angle Cavitation Reduction
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Solution Overview
Problem
Existing ship propulsion arrangements do not optimize water inflow to propellers, leading to inefficiencies, increased noise and vibrations, and reduced component lifespan due to cavitation and asymmetric forces.
Innovation Solution
The propulsion unit is mounted with a vertical tilt angle of 1 to 8 degrees and a toe-out position, improving water inflow to the propeller, reducing noise and vibrations, and optimizing shaft line alignment to enhance efficiency and reduce loads on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the propulsion unit is mounted with a vertical tilt angle of 1 to 8 degrees, then propeller efficiency is improved and noise and vibrations are reduced, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by introducing a vertical tilt angle of 1 to 8 degrees to the propulsion unit shaft line. This angular parameter modification optimizes water inflow to the propeller, improving efficiency while reducing cavitation-induced noise and vibrations. The specific angle range represents a controlled parameter change that balances performance gains with structural feasibility.
2Ease of operation
If the propulsion unit is mounted with a toe-out position, then steerability is improved, but the device complexity increases
Solution Approach 1:
The patent applies asymmetry by configuring the propulsion unit with a toe-out position, where the shaft line is angled outward from the vertical axis. This asymmetric mounting arrangement improves steerability by optimizing the interaction between the propeller thrust and the hull, allowing better directional control without requiring additional steering mechanisms.
3Device complexity
If the shaft line is aligned vertically without tilt, then the device complexity is minimized, but noise and vibrations increase due to cavitation
Solution Approach 1:
The patent resolves this contradiction by changing the shaft line parameter from vertical alignment to a tilted configuration with 1 to 8 degrees vertical tilt. This parameter modification improves water inflow conditions to the propeller, significantly reducing cavitation phenomena that cause noise and vibrations, while maintaining a relatively simple single-unit mounting structure without complex mechanical adjustments.
4Device complexity
If the shaft line operates without optimized tilt angle, then the device complexity is reduced, but asymmetric forces increase reducing component lifespan
Solution Approach 1:
The patent addresses this contradiction by optimizing the shaft line tilt angle parameter to 1 to 8 degrees vertical tilt. This angular parameter optimization aligns the propeller thrust more symmetrically with the hull structure, reducing asymmetric lateral forces that would otherwise increase bearing loads and reduce component lifespan. The solution maintains structural simplicity while improving force distribution through precise angular parameter selection.
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 enhances propeller efficiency, reduces noise and vibrations, and extends the lifespan of bearings and other components by minimizing asymmetric forces and cavitation, while improving steerability and fuel efficiency in large ships.
Implementation Method 1
a propeller at the front end of the chamber, said propeller being connected by means of a shaft to the electric motor
Implementation Method 2
The vertical tilt angle of the at least one propulsion unit improves the water inflow angle to the propeller, which improves the efficiency of the propeller. The vertical tilt angle of the at least one propulsion unit also reduces noise and vibrations in the hull of the ship, which are due to cavitation as the improved inflow angle to the propeller reduces cavitation.
Data Source
Figure 1~2
Figure 3~4
AI summary
The propulsion arrangement comprises at least one propulsion unit (10) situated at the stem of the ship comprising a hull (100) having a horizontal water line (WL) and a center line (CL). The at least one propulsion unit (10) comprises a hollow support structure (11) attached to the hull, a chamber (12) attached to the support structure, an electric motor (13) within the chamber (12), a propeller (15) at the front end of the chamber (12), said propeller (15) being connected through a shaft to the electric motor (13), and a pivotably supported rudder (16) at the rear end of the chamber (12). The at least one propulsion unit (10) is mounted so that the shaft line (SL) forms a vertical tilt angle (α) in the range of 1 to 8 degrees in relation to the water line (WL) so that the front end of the chamber (22) is lower than the rear end of the chamber (22) in relation to the water line (WL).