CMC Turbine Ring Sectors With Rigid Tab Mounting

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Solution Overview

Problem

The existing resilient mounting of ceramic matrix composite (CMC) turbine ring sectors in gas turbine aeroengines is incompatible with finishing machining, causes undesirable vibratory phenomena, and affects gas flow sealing due to radial clearance and differential expansion between CMC and metal structures.

Innovation Solution

A turbine ring assembly with CMC ring sectors having π-shaped sections and tabs engaged without radial clearance, where one tab is secured by a U-shaped hook and the other by a fitted clip, with axial engagement and a sealing gasket for effective thermal decoupling and sealing, and using a fiber preform made by three-dimensional weaving and chemical vapor infiltration for enhanced mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If resilient mounting with radial clearance is used to accommodate differential expansion, then thermal expansion compatibility is improved, but machining precision deteriorates and harmful vibrations are generated

Engineering Contradiction:

Improvethermal expansion compatibilityVSAvoidmachining precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent changes the mounting parameter from resilient with clearance to rigid without clearance, eliminating the radial clearance that causes machining issues while maintaining thermal expansion compatibility through the precise fit and thermal design of the CMC ring sector assembly

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The use of ceramic matrix composite (CMC) material for the ring sectors provides inherent thermal stability and low thermal conductivity, enabling the rigid mounting without clearance to accommodate thermal expansion differences between the CMC and metal support structure

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If resilient mounting is used to accommodate differential expansion, then thermal expansion compatibility is improved, but harmful factors increase due to vibratory phenomena

Engineering Contradiction:

Improvethermal expansion compatibilityVSAvoidvibratory phenomena

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the mounting parameter from resilient with clearance to rigid without clearance, eliminating the radial clearance that causes harmful vibrations while maintaining thermal expansion compatibility through the precise fit and thermal design of the CMC ring sector assembly

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent eliminates the resilient mounting component entirely, replacing it with a direct rigid connection that achieves both thermal expansion compatibility and vibration reduction, simplifying the structure and removing the source of harmful vibratory phenomena

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Adaptability or versatility

If tabs are engaged with radial clearance in housings, then thermal expansion accommodation is improved, but sealing performance deteriorates

Engineering Contradiction:

Improvethermal expansion accommodationVSAvoidsealing performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the engagement parameter from radial clearance to no radial clearance, creating a tight fit between the tabs and housings that ensures effective sealing of the gas flow passage while accommodating thermal expansion through the thermal properties of the CMC material and the precise dimensional design

Inventive Principle:

Principle #35Parameter changes

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 provides improved compatibility with machining, reduces vibratory issues, enhances sealing, and accommodates thermal expansion differences, resulting in a more efficient and stable turbine ring assembly with improved mechanical properties and reduced emissions.

Implementation Method 1

CMC materials are known for their good mechanical properties, which make them suitable for constituting structural elements, and for their capacity to conserve those properties at high temperatures

Methodology Applied

Scientific EffectThermal stability:

Implementation Method 2

using a fiber preform made by three-dimensional weaving and chemical vapor infiltration for enhanced mechanical properties

Methodology Applied

Scientific EffectChemical vapor infiltration: Chemical Vapour Deposition

Implementation Method 3

the resilient mounting presents several drawbacks. Thus, such resilient mounting is poorly compatible with the finishing machining that is conventionally performed after initial mounting of the ring sectors

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9080463B2Turbine ring assembly

Publication Date: 2015.07.14 GERAKL

AI summary

A turbine ring assembly includes a ring support structure and a plurality of ring sectors, each including a single piece of ceramic matrix composite material. Each ring sector includes a first portion forming an annular base with an inside face defining an inside face of the turbine ring and an outside face from which there extends two tab-forming portions including ends that are engaged in housings in the ring support structure. The ring sectors present a section that is substantially π-shaped and the ends of the tabs are held without radial clearance by the ring support structure. The tabs can have a free length in meridian section that is not less than three times their mean width.