Twin-Propeller Phase Control for Cavitation Pressure Fluctuation
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Solution Overview
Problem
Twin-propeller ships experience significant pressure fluctuation and vibration due to cavitation, leading to increased noise and complex processes, as each propeller induces pressure fluctuations that combine to create larger and more complex overall effects compared to single-propeller ships.
Innovation Solution
A method utilizing real-time vibration information to adjust the rotation angles of twin-propeller ship propellers, specifically by measuring vibration signals, determining an optimum relative rotation angle, and controlling the propeller phase to minimize pressure fluctuation through a vibration sensor system, analysis system, controller, encoders, and propeller phase control system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If twin propellers are used to increase propulsion power, then the power and speed of the ship are improved, but the pressure fluctuation and vibration increase significantly
Solution Approach 1:
The patent applies periodic action by adjusting the rotation angles of propellers at specific intervals (e.g., every 15 degrees) to create destructive interference patterns that periodically cancel out pressure fluctuations. The controller systematically varies propeller rotation angles to achieve optimal phase differences that minimize cavitation-induced pressure variations.
Solution Approach 2:
The patent changes the rotation angle parameter of the propellers to optimize performance. By adjusting the rotation angle between 0-360 degrees and calculating optimal phase differences, the system modifies operational parameters to reduce pressure fluctuation while maintaining propulsion effectiveness.
2Object-generated harmful factors
If the rotation angle of propellers is adjusted to minimize pressure fluctuation, then vibration and noise are reduced, but the control complexity increases
Solution Approach 1:
The patent implements feedback by using vibration sensors to continuously monitor pressure fluctuations and feed this information back to the controller. The controller then adjusts propeller rotation angles based on real-time vibration data, creating a closed-loop control system that automatically minimizes pressure fluctuation without requiring complex manual intervention.
Solution Approach 2:
The patent replaces complex mechanical control mechanisms with an electronic control system that uses sensors, processors, and actuators. This substitution simplifies the overall control architecture by using electronic signal processing and calculation algorithms instead of intricate mechanical linkages and manual adjustment mechanisms.
3Object-generated harmful factors
If real-time vibration monitoring is implemented to optimize propeller rotation, then pressure fluctuation decreases, but the system complexity and cost increase
Solution Approach 1:
The patent applies self-service by enabling the system to automatically monitor its own vibration levels and adjust its operation accordingly. The vibration sensors monitor the system's own performance, and the controller autonomously makes adjustments to propeller rotation angles, eliminating the need for external monitoring or manual intervention.
Solution Approach 2:
The patent achieves multi-functionality by using the same sensor and control systems for multiple purposes: monitoring vibration, calculating optimal rotation angles, adjusting propeller phases, and maintaining propulsion efficiency. This universal approach reduces overall system complexity compared to having separate dedicated systems for each function.
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 method effectively decreases pressure fluctuation by optimizing the relative rotation angle, reducing vibration and noise by up to 25% through destructive interference, maintaining propeller states in real-time according to sailing conditions.
Implementation Method 1
Pressure fluctuation means pressure change induced on a surface of a hull by cavitation that occurs when propellers rotate
Implementation Method 2
adjusting a phase difference in a pressure fluctuation-time history so as to decrease total pressure fluctuation induced by the two propellers
Data Source
AI summary
Disclosed is a method of decreasing pressure fluctuation induced on a surface of a hull due to propeller cavitation by using real-time vibration information and adjusting rotation angles of two propellers of a twin-propeller ship.