Deformable Blade Spacer for Windmilling Blade Retention

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Solution Overview

Problem

Existing spacers in gas turbine engines face challenges in providing sufficient force to secure blades during windmilling conditions without causing installation/removal difficulties and risking damage to the spacer or neighboring hardware.

Innovation Solution

A deformable spacer with a compressible sleeve and movable endplates or tabs that exert a customizable force on the blade root, using materials like elastomeric and metallic components, allowing for easy installation and removal by adjusting the compression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spacer exerts high force on the blade to keep it in place during windmilling conditions, then blade security is improved, but installation and removal become difficult and damage risk increases

Engineering Contradiction:

Improveblade securityVSAvoidinstallation and removal ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The spacer transitions from a rigid component to a deformable one that changes its mechanical properties based on operational conditions. During installation, the spacer is soft and compliant, allowing easy compression and installation. During windmilling operation, it becomes rigid and exerts sufficient force to secure the blade. This dynamic property change resolves the contradiction between ease of installation and blade security.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The spacer's material properties are changed based on operational phase. The elastomeric material allows the spacer to be compressed during installation (soft state) and then expands to exert securing force during operation (rigid state). This parameter change enables the spacer to provide high blade security during windmilling while maintaining ease of installation and removal.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If a spacer exerts high force on the blade to prevent windmilling, then blade position stability is improved, but the spacer and neighboring hardware are at risk of damage

Engineering Contradiction:

Improveblade position stabilityVSAvoiddamage risk

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The elastomeric material of the spacer allows it to dynamically adjust its stiffness parameter. During installation and removal, the spacer remains soft to minimize damage risk to hardware. During windmilling conditions, the spacer becomes rigid to provide sufficient blade position stability. This parameter change resolves the contradiction between stability and damage risk.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The deformable nature of the elastomeric spacer provides inherent cushioning during installation and removal operations. The material absorbs impact forces and prevents excessive stress from being transmitted to the blade root and hub, thereby reducing damage risk beforehand while still providing necessary stability during operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Force

If a rigid spacer is used to secure the blade, then blade retention force is improved, but installation and removal become difficult

Engineering Contradiction:

Improveblade retention forceVSAvoidinstallation ease

Core Design Contradiction:

ForceVSEase of manufacture

Solution Approach 1:

The spacer's mechanical properties are changed based on operational phase. The elastomeric material allows the spacer to be compressed during installation (soft state) and then expands to exert securing force during operation (rigid state). This parameter change enables the spacer to provide high blade security during windmilling while maintaining ease of installation and removal.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Inventive Principle:

Principle #15Dynamics

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 spacer effectively secures blades without overloading, reducing installation/removal stress, and minimizing damage risks while maintaining blade position during windmilling.

Implementation Method 1

A deformable spacer situated between the rotor hub and the blade root in the slot

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

Moving at least one of the first, second, and third end plates towards another of the first, second, and third endplates compresses at least one of the first and second segments of the sleeve such that the spacer exerts a force on the blade

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS12448898B2Blade spacer

Publication Date: 2025.10.21 RTX CORP

AI summary

A fan includes a rotor hub comprising a slot and a blade comprising an airfoil extending from a blade root in a first direction. The blade root is configured to be received in the slot. The fan also includes a deformable spacer situated between the rotor hub and the blade root in the slot, a first blade lock situated at a first side of the slot, and a second blade lock situated at a second side of the slot opposite the first side. At least one of the first and second blade locks includes a tab configured to extend between the blade root and the rotor hub and to compress the spacer such that the spacer exerts a force on the blade in the first direction. A method of assembling a fan and another example fan are also disclosed.