Ship Propeller Speed Control to Reduce Cavitation

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Solution Overview

Problem

Existing methods to reduce cavitation in ship propellers either require structural changes to the propeller blades, which decrease propulsive force, or do not effectively address cavitation occurrence.

Innovation Solution

A control method that determines the rotational angle range of the propeller corresponding to the cavitation occurrence section and adjusts the propeller's rotational speed within that range to minimize cavitation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the structure of the propeller blades is changed to reduce cavitation, then cavitation is reduced, but the intensity of propulsive force generated decreases

Engineering Contradiction:

ImprovecavitationVSAvoidpropulsive force

Core Design Contradiction:

Object-affected harmful factorsVSPower

Solution Approach 1:

The patent applies dynamics by making the propeller rotational speed adjustable rather than fixed. The control method dynamically changes the rotational speed based on detected cavitation conditions, allowing the system to adapt to different operating scenarios. This resolves the contradiction by enabling optimal performance at different speeds without structural modifications.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameter (rotational speed) to resolve the cavitation issue. Instead of modifying the propeller structure, the system adjusts the rotational speed parameter to reduce cavitation while maintaining propulsive force intensity. This is achieved through real-time detection and control of rotational speed based on cavitation detection.

Inventive Principle:

Principle #35Parameter changes

2Power

If the rotational speed of the propeller is increased to improve propulsion, then propulsive force increases, but cavitation occurs more intensely

Engineering Contradiction:

Improvepropulsive forceVSAvoidcavitation

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent implements feedback control by continuously detecting cavitation conditions and using this information to adjust the rotational speed. The control method monitors cavitation occurrence and modifies the rotational speed accordingly, creating a closed-loop system that balances propulsive force and cavitation reduction.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies periodic action through continuous monitoring and adjustment of rotational speed based on cavitation detection. The system periodically evaluates cavitation conditions and makes corresponding adjustments to rotational speed, maintaining optimal performance while minimizing cavitation throughout the operating cycle.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS20250074565A1Method of controlling rotational speed of propeller of ship to reduce cavitation

Publication Date: 2025.03.06 MOTH CO LTD

AI summary

Disclosed is a method of controlling a rotational speed of a propeller of a ship to reduce cavitation. The method may reduce cavitation by determining a rotational angle range of a propeller corresponding to a cavitation occurrence section when cavitation occurs during sailing of a ship and by increasing or reducing the rotational speed of the propeller within the determined rotational angle range of the propeller corresponding to the cavitation occurrence section. Therefore, it is possible to simply reduce cavitation only by controlling the rotational speed of the propeller without changing the structure of the propeller.