Flow Guide Surface With Free-End Fins For Propulsion Power Reduction

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Solution Overview

Problem

Existing devices for reducing the drive power requirement of watercraft are ineffective for fast and very fast ships, as they generate significant resistance to propeller inflow, limiting their application to slower vessels.

Innovation Solution

A flow control surface with protruding fins, where one fin is attached at one end and free at the other, and a second fin connected to the hull, is designed to direct water flow onto the propeller, reducing resistance and allowing for efficient pre-rotation, thereby reducing drive power requirements across various ship speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a fore-nozzle with fins is used to reduce propulsion power requirement, then fuel efficiency is improved, but resistance to propeller inflow increases

Engineering Contradiction:

Improvefuel efficiencyVSAvoidresistance to propeller inflow

Core Design Contradiction:

Loss of energyVSForce

Solution Approach 1:

The device divides the flow guidance function into two separate components: a fore-nozzle for flow direction and separate fins for pre-swirl generation. This segmentation allows each component to be optimized independently, reducing overall resistance while maintaining energy efficiency benefits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fins are extracted from the fore-nozzle structure and positioned separately behind it. This extraction removes the harmful interaction between fins and fore-nozzle that causes increased resistance, while preserving the beneficial pre-swirl effect for propeller efficiency.

Inventive Principle:

Principle #2Taking out (Extraction)

2Productivity

If a fore-nozzle with fins is used to reduce propulsion power requirement, then slower ships benefit more, but fast and very fast ships cannot effectively use it

Engineering Contradiction:

Improvepropulsion power reduction effectivenessVSAvoidapplicability across different ship speeds

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

By separating the fore-nozzle from the fins, the system can be independently optimized for different speed regimes. The fore-nozzle can be sized and shaped for fast ships with lower resistance requirements, while the fins can be configured to provide adequate pre-swirl without excessive resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The device allows for parameter optimization across different ship speeds by independently adjusting fore-nozzle dimensions, fin geometry, and spacing. This enables the same basic system architecture to serve both slow and fast vessels effectively.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If fins are arranged in the fore-nozzle to generate pre-swirl, then propeller jet losses are reduced, but the device complexity increases

Engineering Contradiction:

Improvepropeller jet lossesVSAvoidstructural complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The fins are extracted from the fore-nozzle structure and positioned separately behind it. This simplifies the fore-nozzle design to a basic flow direction component while the fins are mounted independently on the hull or stern tube, reducing overall structural complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The separate fin arrangement can serve multiple functions: generating pre-swirl for the propeller, reducing resistance compared to integrated designs, and potentially serving as structural support elements. This multi-functionality reduces the need for additional components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively reduces drive power requirements and improves stability, enabling the device to be used on fast and very fast ships while maintaining efficiency, by minimizing resistance and optimizing propeller inflow.

Implementation Method 1

The flow guide surface is arranged and designed such that the water flow is at least partially directed onto a propeller

Methodology Applied

Scientific EffectFluid flow guidance:

Implementation Method 2

thanks to the fins installed in the fore-nozzle, to reduce losses in the propeller jet by generating targeted pre-swirl

Methodology Applied

Scientific EffectPre-swirl generation: Vortex Ring

Implementation Method 3

The previously known device described above has a relatively high resistance to the propeller inflow

Methodology Applied

Scientific EffectDrag reduction: Drag

Data Source

PatentEP2994379B1Apparatus to reduce required propulsion power of waterborne vessel

Publication Date: 2019.05.01 BECKER MARINE SYSTEMS GMBH & CO KG

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AI summary

The invention relates to a device (100) for reducing the driving power requirement of a watercraft, comprising a flow guiding surface (10) from which at least one first fin (20) projects. A first end of said first fin is fixed to the flow guiding surface (10), and a second end (23) of the first fin is embodied as a free end.