Ceramic Tile Shielding for Metal Fastener Thermal Protection

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Solution Overview

Problem

Metal fasteners used to secure ceramic matrix composite (CMC) tiles in gas turbine combustors lose strength and can melt at high operating temperatures, undermining the high-temperature capability of CMCs.

Innovation Solution

The use of metallic fasteners shielded from heat by adjacent ceramic tiles, with preformed apertures and dimples to allow expansion and contraction, and strategically positioned to maintain a uniform distance for even heat distribution, reducing thermal gradients and the need for cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal fasteners are used to secure CMC tiles to the metallic shell, then the tiles can be firmly attached, but the fasteners lose strength and may melt at CMC operating temperatures

Engineering Contradiction:

Improvefastener strengthVSAvoidoperating temperature

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

A ceramic intermediary component is introduced between the metal fastener and the CMC tile. This ceramic intermediary can withstand the high temperatures that would otherwise damage the metal fastener, allowing the fastener to securely attach the tile without being directly exposed to extreme thermal conditions

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional direct mechanical fastening with a thermal field management approach. By using ceramic intermediaries and strategically positioned cooling channels, the system manages thermal fields to protect mechanical components, substituting pure mechanical attachment with a combined thermal-mechanical solution

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the metallic shell and fasteners are cooled to maintain their strength, then the fasteners can withstand high temperatures, but the high temperature capability of CMCs is undermined

Engineering Contradiction:

Improvefastener reliabilityVSAvoidtemperature uniformity

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

Cooling channels are strategically positioned only in specific locations where metal components require thermal protection, rather than cooling the entire combustor structure. This localized cooling approach maintains temperature uniformity in the CMC regions while providing necessary thermal management only where metal fasteners and shell are present

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The combustor structure is segmented into distinct thermal zones: regions with CMC tiles that operate at high temperatures and regions with metal fasteners that require cooling. This segmentation allows different thermal conditions in different parts of the system, enabling both CMC high-temperature capability and metal fastener reliability

Inventive Principle:

Principle #1Segmentation

3Productivity

If CMC tiles are used to withstand high temperatures, then operating efficiency is increased, but the tiles need to be secured with metal fasteners that cannot withstand those temperatures

Engineering Contradiction:

Improveoperating efficiencyVSAvoidfastener strength at temperature

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system employs a composite structure combining metal fasteners, ceramic intermediaries, and CMC tiles. Each material is used where its properties are most advantageous: metal for mechanical strength at lower temperatures, ceramic for high-temperature interface, and CMC for high-temperature structural integrity

Inventive Principle:

Principle #40Composite 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

Extends the lifespan of fasteners, reduces thermal gradients, and eliminates the need for cooling, enhancing the high-temperature capability of CMCs and reducing NOx emissions by maintaining temperature uniformity.

Implementation Method 1

portions of adjacent ceramic tiles coupled to the metallic shell shield the metallic fasteners from heat generated in the combustion chamber

Methodology Applied

Scientific EffectThermal shielding: Thermal Insulation

Implementation Method 2

preformed apertures in the ceramic tile are sized to locate the ceramic tile while also allowing for expansion/contraction of the ceramic tile as the ceramic tile is heated/cooled during use of the combustor

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

The ceramic liner includes a plurality of ceramic tiles coupled to the metallic shell and arranged to shield the metallic shell from heat generated in the combustion chamber

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS11274829B2Shell and tiled liner arrangement for a combustor

Publication Date: 2022.03.15 ROLLS ROYCE CORP

AI summary

A combustor adapted for use in a gas turbine engine is disclosed. The combustor includes a metallic shell forming a cavity and a ceramic liner arranged in the cavity of the metallic shell. The ceramic liner defines a combustion chamber in which fuel is burned during operation of a gas turbine engine. The ceramic liner includes a plurality of ceramic tiles mounted to the metallic shell and arranged to shield the metallic shell from heat generated in the combustion chamber.