Turbomachine Rotor Disc Axial Blade Retention

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Solution Overview

Problem

In low-pressure turbine rotor discs of turbomachines, the downstream retaining rings and mobile rings face significant mechanical and thermal stresses, leading to gas leaks and complex, costly replacement processes.

Innovation Solution

The rotor disc design incorporates downstream radial walls with integrated ventilation channels, eliminating the need for downstream retaining rings and simplifying blade assembly, while the ventilation channels ensure effective cooling and reduce air flow leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If downstream retaining rings are used to axially secure blades, then blade retention is achieved, but device complexity and susceptibility to mechanical/thermal stresses increase

Engineering Contradiction:

Improveblade retentionVSAvoidassembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the blade retention function directly into the rotor disc structure by forming axial blocking surfaces on the radial walls of the recesses. This integration eliminates the need for separate downstream retaining rings and movable rings, reducing the number of components while maintaining effective blade retention through the disc's own structural features.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and eliminates the downstream retaining ring and movable ring components from the assembly. By removing these separate parts and integrating their retention function directly into the rotor disc's recess structure, the design simplifies the overall assembly and reduces susceptibility to mechanical and thermal stresses that affect separate retaining components.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If downstream retaining rings and movable rings are used, then blade axial locking is achieved, but the lifespan is reduced due to mechanical and thermal stresses

Engineering Contradiction:

Improveblade axial lockingVSAvoidretaining ring lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The retention function is merged into the rotor disc structure itself through axial blocking surfaces formed on the radial walls of recesses. This integration means the retention structure experiences the same thermal and mechanical conditions as the disc, eliminating stress concentration at interfaces between separate components and thereby extending the operational lifespan of the retention system.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If through-holes are used for recesses, then blade assembly is simplified, but gas leaks occur due to axial retaining rings

Engineering Contradiction:

Improveblade assemblyVSAvoidgas leaks

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent transitions from using separate axial retaining rings (one-dimensional solution) to forming axial blocking surfaces directly on the radial walls of recesses (two-dimensional integration). This dimensional change allows the retention function to be built into the disc structure, preventing gas leaks while maintaining ease of blade assembly through the same recess structure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Reliability

If multiple retaining components are used, then blade retention is ensured, but weight increases

Engineering Contradiction:

Improveblade retentionVSAvoidrotor weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines multiple separate retaining components (downstream retaining ring, movable ring, upstream retaining ring) into a single integrated rotor disc structure with axial blocking surfaces. This merging eliminates the need for multiple separate parts, reducing the overall weight of the rotor assembly while maintaining reliable blade retention through the integrated blocking surfaces.

Inventive Principle:

Principle #5Merging (Combining)

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

This design reduces the complexity and cost of assembly, minimizes weight, and enhances turbomachine efficiency by controlling cooling flow and reducing leakage, thereby improving overall performance.

Implementation Method 1

each downstream radial wall comprising a ventilation channel for the cell, comprising an inlet orifice which opens into the cell and an outlet orifice which opens onto a downstream surface of the disc

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentEP3847339B1Rotor disc with axial retention of the blades, assembly of a disc and a ring, and turbomachine

Publication Date: 2022.12.28 SAFRAN AIRCRAFT ENGINES SAS

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AI summary

The invention relates to a rotor disc (36) for a turbomachine (10), the disc (36) extending circumferentially about an axis (A) and having a plurality of cells (60) configured to receive the roots of blades (58), each cell (60) having a downstream radial wall (64) configured to axially lock the blade root (58) in the cell (60), each downstream radial wall (64) comprising a ventilation channel (66) for the cell (60) having an inlet orifice (68), which opens into the cell (60), and an outlet orifice (70), which opens onto a downstream surface of the disc (36). The invention also relates to an assembly for a turbomachine, comprising such a disc (36) and an upstream retaining ring, and to a turbomachine comprising such an assembly.