Propeller Shaft Cavitation Control via Dynamic Oscillation
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Solution Overview
Problem
Existing control systems for propeller shafts in electrical propulsion vessels lack efficient and robust management, particularly in detecting adverse operating conditions caused by cavitation, which affects propulsion efficiency and wear, leading to suboptimal energy conversion and increased fuel consumption.
Innovation Solution
A controller and method that utilize a combination of physical sensors and signal processing units to detect and analyze oscillations in the propeller shaft, identifying cavitation-induced movements and adjusting torque commands to mitigate parasitic oscillations, thereby enhancing propulsion efficiency and reducing cavitation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional conservative design methods are used for the mechanical propulsion system, then reliability is improved, but propulsion efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by enabling the propeller shaft to move dynamically in response to cavitation forces rather than being rigidly fixed. The control system actively adjusts shaft position to counteract cavitation-induced oscillations, transforming a static conservative design into a dynamic adaptive system that maintains reliability while improving propulsion efficiency by 3-4%
Solution Approach 2:
The patent implements feedback control by using sensors to detect shaft oscillations and cavitation conditions, then feeding this information back to the control system which adjusts shaft position in real-time. This closed-loop feedback mechanism allows the system to maintain reliability through continuous monitoring while optimizing propulsion efficiency through active compensation
2Stability of the object's composition
If the propeller shaft is rigidly fixed to prevent movement, then stability is improved, but cavitation-induced oscillations worsen
Solution Approach 1:
The patent applies the counterweight principle by using the control system to generate opposing forces that counteract cavitation-induced oscillations. The control system adjusts shaft position to create counterbalancing effects that neutralize harmful oscillations while maintaining overall shaft stability, preventing both excessive movement and rigid fixation
3Use of energy by moving object
If advanced control systems are implemented to manage cavitation, then propulsion efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by designing a control system that autonomously monitors and adjusts shaft position without requiring complex external intervention. The system uses onboard sensors and control algorithms to automatically compensate for cavitation effects, reducing the need for complex external control infrastructure while maintaining improved propulsion efficiency
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 solution enables a 3-4% increase in fuel-to-propulsion power conversion efficiency over the vessel's lifecycle by effectively managing cavitation and reducing adverse oscillations, leading to more efficient operation without actual cavitation occurrence.
Implementation Method 1
a vibration sensor configured to detect movement of the propeller shaft
Implementation Method 2
cavitation is a nonlinear phase-change hydrodynamic phenomenon introducing a wholly new energy flow
Implementation Method 3
US 2 320 721 A discloses an electrodynamic oscillation damper
Data Source
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AI summary
There is provided mechanisms for for controlling movement of a propeller shaft on a vessel. A controller comprises processing circuitry. The processing circuitry is configured to cause the controller to detect movement of the propeller shaft by determining a signature of a sustained oscillation of the propeller shaft. The processing circuitry is configured to cause the controller to control movement of the propeller shaft according to the determined signature.