Rotor Disk Hook Recess for Crack Prevention

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Solution Overview

Problem

Turbomachine rotor disks experience material damage and crack propagation due to tension and compression forces generated by sealing flange sectors, leading to shear plane formation and hook failure.

Innovation Solution

The rotor disk is equipped with circumferentially distributed hooks featuring a recess below the internal radius of curvature, which eliminates shear plane formation and crack generation by distributing forces and maintaining structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sealing flange sectors are installed on the rotor disk through axial hooks, then the blade roots are sealed in the slots, but opposing forces from flange sector expansion damage the hooks and create shear planes that generate cracks

Engineering Contradiction:

Improvesealing reliabilityVSAvoidhook strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A recess is introduced at the specific location where the second element of the hook joins the rotor disk, below the internal radius of curvature. This local structural modification redistributes the stress field in the critical zone, preventing shear plane formation and crack initiation while preserving the overall hook strength and sealing function.

Inventive Principle:

Principle #3Local quality

2Reliability

If the hooks are subjected to tension and compression forces from flange sector expansion, then the sealing function is maintained, but material damage accumulates and cracks propagate leading to hook failure

Engineering Contradiction:

Improvesealing functionVSAvoidhook service life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The recess is designed in advance to preemptively cushion and redistribute the cyclic tension and compression forces generated by flange sector expansion. By modifying the stress distribution before damage occurs, the recess prevents material fatigue accumulation and extends the service life of the hooks while maintaining sealing reliability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the hooks are designed with a recess below the internal radius of curvature, then shear plane formation and crack generation are eliminated, but the hook structure is modified

Engineering Contradiction:

Improvecrack resistanceVSAvoidhook geometry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The recess is localized to a specific region below the internal radius of curvature where stress concentration occurs, rather than modifying the entire hook structure. This targeted geometric modification eliminates shear plane formation and crack generation while minimizing the overall change to the hook design.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9689278B2Rotor disk including a plurality of hooks

Publication Date: 2017.06.27 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A rotor disk comprises a plurality of circumferentially distributed hooks, the set of hooks defining an annular groove adapted to cooperate with at least two flange sectors. At least one of the hooks comprises a second element through which a recess is formed which opens up at each of the transverse flanks of the second element and at the internal peripheral surface of the second element.