Composite Compressor Casing with Perforated Metallic Ring

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Solution Overview

Problem

Existing methods for applying abradable materials in axial turbomachine compressors face challenges with retention on composite supports due to thermal expansion differences and lack of mechanical strength, particularly when using plasma spraying, which can lead to interface fragility and inadequate sealing.

Innovation Solution

A composite shell with a metallic ring having thermal expansion characteristics matched to the composite support, where the ring is perforated for improved bonding and degassing, and an abradable layer is applied via plasma spraying, providing mechanical strength and protection against mechanical stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If abradable material is applied directly to composite support via plasma spraying, then manufacturing efficiency is improved, but retention and mechanical strength deteriorate due to thermal expansion differences

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidretention of abradable layer

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

A metallic ring is introduced as an intermediary layer between the composite support and the abradable material. This ring serves as a mediator that resolves the thermal expansion mismatch issue, allowing plasma spraying to be used effectively while ensuring proper retention of the abradable layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution employs a composite structure combining metallic ring with composite support. This multi-material approach leverages the advantages of each material: the metallic ring provides thermal expansion compatibility and bonding surface, while the composite support provides structural integrity and weight benefits.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If abradable material is applied to composite support, then mass is reduced, but interface fragility increases due to thermal expansion differences

Engineering Contradiction:

Improvemass of compressorVSAvoidinterface durability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The metallic ring acts as a protective intermediary that shields the composite support from direct thermal and mechanical stresses. This intermediary layer prevents interface fragility while maintaining the weight benefits of the composite structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution changes the thermal and mechanical parameters at the interface by introducing the metallic ring. This alters the thermal expansion characteristics and stress distribution, thereby improving interface durability without sacrificing the mass reduction benefits.

Inventive Principle:

Principle #35Parameter changes

3Strength

If perforations are added to metallic ring, then bonding and degassing are improved, but device complexity increases

Engineering Contradiction:

Improvebonding strengthVSAvoidring structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The metallic ring is designed with a porous structure featuring numerous perforations. This porosity enables improved bonding of the abradable material and facilitates degassing during the plasma spraying process, while the regular pattern of perforations keeps the manufacturing process relatively simple.

Inventive Principle:

Principle #31Porous materials

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 enhances the mechanical strength and durability of the abradable layer, ensures effective sealing, and allows for efficient manufacturing with reduced mass, while maintaining gas-tightness and efficiency in turbomachines.

Implementation Method 1

A composite shell with a metallic ring having thermal expansion characteristics matched to the composite support

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

an abradable layer is applied via plasma spraying

Methodology Applied

Scientific EffectPlasma spraying: Plasma Spray

Data Source

PatentUS9840925B2Axial turbomachine compressor outer casing

Publication Date: 2017.12.12 SAFRAN AERO BOOSTERS SA

AI summary

The invention relates to a casing, particularly of an axial turbomachine compressor. This casing comprises a support of cylindrical overall shape made of composite material, a metal ring fitted by bonding to the internal surface of the support, and a layer of abradable material fitted by plasma spray onto the internal surface of the metal ring. The metal ring is preferably made of stainless steel and is preferably perforated. The perforation allows better keying of the adhesive and allows the degassing thereof. The external surface of the metal ring is preferably sandblasted prior to bonding. Its internal surface is also preferably sandblasted prior to the plasma spraying of the abradable material.