Static Dissipative Coating for Gas Turbine Fan Blades

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Solution Overview

Problem

As gas turbine fan blades increase in size, they accumulate static electric charges due to air movement, which conventional conductive materials struggle to dissipate effectively, especially when not grounded, leading to potential electrical issues and inefficiencies.

Innovation Solution

A fan blade with a metallic body coated in a static dissipative material containing carbon black, combined with a conductive leading edge sheath and non-conductive pads for grounding, facilitates the dissipation of static charges while preventing galvanic action.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fan blade size is increased to improve thrust and efficiency, then more static electric charge is accumulated due to larger surface area exposed to air movement, but conventional conductive materials become less effective at dissipating the charge

Engineering Contradiction:

Improvethrust and efficiencyVSAvoidstatic charge dissipation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the electrical conductivity parameter of the coating material from highly conductive (conventional) to statically dissipative (controlled conductivity). This allows the coating to slowly dissipate static charge over time rather than immediately conducting it, preventing charge buildup on larger fan blades while maintaining material compatibility with aluminum alloys.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite coating materials consisting of polymeric resin combined with metal particles (such as aluminum, zinc, or magnesium). This composite structure provides both the protective coating function and the static dissipative properties needed for large aluminum fan blades, combining benefits of both polymer and metal materials.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If aluminum alloy is used instead of titanium to reduce fan blade weight, then weight is reduced, but the blade loses electrical conductivity and ability to ground static charge

Engineering Contradiction:

Improvefan blade weightVSAvoidelectrical grounding capability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent extracts the electrical conductivity function from the base aluminum alloy material by adding a separate conductive coating layer. This allows the aluminum alloy to maintain its weight advantage while the coating layer provides the necessary static charge dissipation capability that pure aluminum lacks.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The conductive coating acts as an intermediary layer between the non-conductive aluminum alloy blade and the grounding system. This intermediate coating enables electrical charge transfer without requiring the base material itself to be conductive, thus preserving the weight benefits of aluminum while restoring grounding capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If conductive metal coating is applied to aluminum fan blade, then static charge can be conducted, but galvanic corrosion occurs between dissimilar metals

Engineering Contradiction:

Improvestatic charge dissipationVSAvoidresistance to galvanic corrosion

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent uses sacrificial metal particles (zinc or magnesium) in the coating that are more anodic than aluminum. These particles act as disposable corrosion protection elements that corrode preferentially, protecting the aluminum substrate and other metal particles in the coating from galvanic corrosion while maintaining static dissipative properties.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the potential harm of galvanic corrosion into a benefit by using sacrificial anode particles (zinc or magnesium) that deliberately corrode first. This controlled galvanic action protects the structural aluminum and maintains coating integrity, turning what would be a harmful corrosion mechanism into a protective corrosion protection system.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 manages static charge dissipation on larger fan blades, enhancing operational safety and efficiency by preventing electrical buildup and ensuring galvanic isolation.

Implementation Method 1

A static dissipative coating material is disposed on the body outer surface and on the root... facilitates the dissipation of static charges

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The static dissipative coating includes a paracrystalline material which includes carbon black

Methodology Applied

Scientific EffectParacrystalline structure:

Data Source

PatentEP3018289B1Fan blade with static dissipative coating

Publication Date: 2018.01.03 UNITED TECH CORP

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AI summary

A fan blade (100) for use in a gas turbine engine, includes a metallic fan blade body (102), including a fan blade body leading edge (108) and body outer surface (102), extending radially outward from a root (106), and a static dissipative coating material (112) disposed on the body outer surface (102).