Integrated Stern Bulb and Flap for Ship Resistance Reduction

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Solution Overview

Problem

Existing ship designs, such as the USS Arleigh Burke (DDG 51) Class destroyer, face challenges in reducing wave resistance and maintaining efficiency while incorporating stern end bulbs and flaps, which are underutilized due to adverse structural effects, and require efficient methods for deploying monitoring devices without compromising hull performance.

Innovation Solution

An integrated stern bulb and flap system with a dual-use bulb having a hollow main body section for storage, attached to the transom, and a forebody section connected to the hull, positioned between flap portions, optimizing hydrodynamics and providing energy savings by reducing wave resistance and allowing for non-penetrative deployment of monitoring devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a stern end bulb is added to reduce wave resistance, then fuel efficiency improves, but structural complexity and adverse hydrodynamic effects increase

Engineering Contradiction:

Improvefuel consumptionVSAvoidstructural complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent combines the stern bulb and stern flap into a single integrated structure. The bulb is positioned between the first and second flap portions, creating a unified hydrodynamic enhancement system that reduces wave resistance while avoiding the structural complications of separate installations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated structure serves multiple functions simultaneously: the bulb portions reduce wave resistance, the flap portions control flow separation, and the hollow interior provides stowage space for monitoring devices. This multi-functionality reduces the need for additional separate structures.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Loss of energy

If stern flaps are installed to reduce propulsive power, then fuel cost savings increase, but structural modifications to the transom are required

Engineering Contradiction:

Improvepropulsive powerVSAvoidstructural modification

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The stern flaps are integrated with the bulb structure, which is itself attached to the transom. This combination allows the flaps to be installed as part of a single structural assembly, reducing the number of separate welding or attachment operations required compared to traditional separate flap installations.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If monitoring devices are deployed using davits or ramps, then deployment capability is achieved, but hull performance is compromised

Engineering Contradiction:

Improvedeployment capabilityVSAvoidhull performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The hollow interior of the integrated bulb-flap structure serves as a stowage space for monitoring devices, eliminating the need for separate deployment structures like davits or ramps. This maintains the hull's original hydrodynamic performance while providing monitoring capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Adaptability or versatility

If a hollow bulb structure is created for stowage space, then monitoring device storage is enabled, but structural complexity increases

Engineering Contradiction:

Improvestowage capabilityVSAvoidstructural complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The hollow interior of the bulb structure provides stowage space for monitoring devices, while the same structure simultaneously reduces wave resistance and works with the flaps to control flow separation. This multi-functionality justifies the structural complexity by eliminating the need for separate stowage compartments.

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 integrated stern bulb and flap system enhances power efficiency by reducing wave resistance and fuel consumption, particularly at high speeds, and enables efficient deployment and recovery of monitoring devices without compromising vessel performance.

Implementation Method 1

Both stern flaps and stern end bulbs interact with the hull to produce a wave system that reduces the total wave resistance

Methodology Applied

Scientific EffectWave resistance reduction:

Implementation Method 2

the stern flap also reduces after-body resistance

Methodology Applied

Scientific EffectHydrodynamic interaction:

Data Source

PatentUS9180933B1Integrated stern bulb and flap

Publication Date: 2015.11.10 THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY

AI summary

The invention is directed to an integrated stern bulb and flap for a water vessel, more particularly, a bulb having a main body section and a forebody section, the bulb positioned between first and second flap portions. The integrated stern bulb and flap provides improved power efficiency by reducing resistance at high speeds. The bulb of the integrated stern bulb and flap may be hollow, the interior being stowage space adding to the payload of the water vessel.