Fan Blade Diode Grounding for Static Charge Dissipation
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Solution Overview
Problem
As gas turbine fan blades have increased in size and weight, the use of non-conductive materials like aluminum coated with polyurethane and fabric pads for insulation has resulted in a loss of electrical grounding, leading to static charge accumulation and potential galvanic corrosion due to the inability to dissipate charges effectively.
Innovation Solution
A diode is positioned between the aluminum fan blade and the titanium lock ring, allowing static charge dissipation from the blade to the rotor while preventing reverse flow to prevent galvanic corrosion, utilizing a diode as an electronic check valve to manage electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-conductive materials (aluminum with polyurethane coating and fabric pads) are used for fan blade insulation, then insulation quality is improved, but electrical grounding is lost leading to static charge accumulation
Solution Approach 1:
A diode is introduced as an intermediary component between the non-conductive fan blade and the conductive rotor hub. The diode allows static charge to dissipate from the blade to the hub while blocking reverse current flow, thus maintaining insulation quality while enabling controlled electrical discharge to prevent charge accumulation.
Solution Approach 2:
The electrical conductivity parameter of the grounding path is made directional through the diode. The system transitions from a purely insulating configuration to one with controlled conductive pathways, allowing charge dissipation in one direction while maintaining insulation in the reverse direction.
2Object-affected harmful factors
If conductive metal fan blades are used, then electrical grounding is maintained, but weight increases and insulation protection is reduced
Solution Approach 1:
The system uses a composite structure combining non-conductive materials (aluminum blade with polyurethane coating and fabric pads) for weight reduction and insulation, with a diode-based grounding element that provides selective electrical connectivity. This composite approach allows the blade to benefit from both insulation and controlled grounding.
Solution Approach 2:
The diode serves as an intermediary that reconciles the conflict between non-conductive blade materials and the need for electrical grounding. It enables charge dissipation without requiring the entire blade structure to be conductive, thus maintaining weight reduction while restoring grounding capability.
3Object-affected harmful factors
If direct electrical connection is made between aluminum fan blade and titanium rotor hub, then static charge dissipates, but galvanic corrosion occurs
Solution Approach 1:
The diode acts as an intermediary that permits electron flow in one direction (from aluminum blade to titanium hub) for charge dissipation while blocking reverse flow. This unidirectional conductivity prevents the bidirectional electron exchange that causes galvanic corrosion, while still allowing static charge to dissipate effectively.
Solution Approach 2:
The electrical conductivity parameter is made asymmetric through the diode, allowing charge dissipation while preventing the reverse current flow that would cause galvanic corrosion. This parameter modification resolves the contradiction by enabling one-way charge transfer.
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 diode-based grounding system effectively dissipates static charges from the fan blade to the rotor, preventing galvanic corrosion and ensuring safe electrical discharge without compromising the non-conductive coating's insulation properties.
Implementation Method 1
A diode is positioned between the aluminum fan blade and the titanium lock ring, allowing static charge dissipation from the blade to the rotor while preventing reverse flow
Data Source
Figure 1A
Figure 1B~2
AI summary
A rotor has a rotor body with at least one slot receiving a blade. The blade has an outer surface, at least at some areas, formed of a first material and having an airfoil extending from a dovetail. The dovetail is received in the slot. A diode is in contact with a portion of the dovetail formed of a second material that is more electrically conductive than the first material. The diode is in contact with a rotating element that rotates with the rotor. The rotating element is formed of a third material. The first material is less electrically conductive than the third material. The diode and the rotating element together form a ground path from the portion of the dovetail into the rotor. An engine and a fan blade are also disclosed.