Torsional Flexing Blade Lock Ring for Gas Turbine Impact Absorption

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Solution Overview

Problem

Existing blade retention systems in gas turbine engines face challenges in securely locking rotor blades against axial movement due to foreign object strikes, leading to potential rotor integrity issues and increased rotational mass from locking mechanisms.

Innovation Solution

A hub assembly with a lock ring and anti-rotation ring design, featuring trapezoidal mounts and circular ring mounts with tabs and axial flanges, allows for torsional flexibility to absorb impact, preventing shear and minimizing weight by allowing deflection, thus retaining the blade root within the hub.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rigid locking mechanisms are used to secure rotor blades against axial movement, then blade retention reliability is improved, but the device complexity and rotational mass increase

Engineering Contradiction:

Improveblade retention reliabilityVSAvoidlocking mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a flexible lock ring with circumferential flexibility that can deflect and flex during foreign object strikes. This flexible structure replaces rigid locking mechanisms, maintaining blade retention reliability while reducing device complexity and rotational mass. The lock ring's ability to flex allows it to absorb impact forces without requiring additional complex locking components.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the mechanical properties of the locking mechanism by using a lock ring with controlled flexibility. The circumferential flexibility parameter allows the lock ring to deform under impact loads, transforming the rigid locking approach into a flexible retention system that maintains reliability with reduced complexity.

Inventive Principle:

Principle #35Parameter changes

2Strength

If heavy locking mechanisms are used to prevent rotor blade movement during foreign object strikes, then rotor integrity is improved, but the rotational mass and energy consumption increase

Engineering Contradiction:

Improverotor integrityVSAvoidrotational mass

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The flexible lock ring serves as a lightweight alternative to heavy rigid locking mechanisms. Its circumferential flexibility enables it to maintain rotor integrity during foreign object strikes by absorbing impact forces through deformation, thereby protecting the rotor without requiring excessive mass.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The lock ring is designed with inherent flexibility that acts as a cushion against foreign object strikes. This pre-designed flexibility allows the structure to absorb impact energy before it can damage the rotor, providing protective cushioning without the need for heavy-duty locking components.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If non-flexible locking structures are used to secure blades, then locking reliability is improved, but the ability to absorb impact energy deteriorates

Engineering Contradiction:

Improvelocking reliabilityVSAvoidimpact energy absorption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The lock ring's circumferential flexibility enables it to absorb impact energy through elastic deformation while maintaining its locking function. The flexible structure can deflect during foreign object strikes and then return to its original position, preserving locking reliability while capturing impact energy that would otherwise be lost or transmitted to the rotor.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent converts the harmful impact energy from foreign object strikes into beneficial elastic deformation of the lock ring. The flexibility that might seem to compromise locking strength actually enables energy absorption, transforming the harmful strike force into a protective mechanism that safeguards the rotor while maintaining retention reliability.

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 retains rotor blades during foreign object strikes by distributing impact force along the circumference, preventing shear and reducing the weight of locking mechanisms, enhancing rotor integrity and efficiency.

Implementation Method 1

desirably, the lock ring will be allowed to flex behind the outer diameter tabs of the hub such that the impact of a foreign object strike will be shared along a circumference of the lock ring

Methodology Applied

Scientific EffectTorsional flexing: Elasticity

Data Source

PatentEP2526262B1Torsional flexing energy absorbing blade lock

Publication Date: 2015.06.03 UNITED TECH CORP

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AI summary

A lock for constraining blades in a hub includes a flexible ring (15) for constraining the blades from moving axially in the hub, a finger (125) attached to the hub (10) for preventing the ring from rotating relative to the hub and whereby the ring flexes about at least a partial circumference thereof if urged axially by the blades (35).