Ceramic Matrix Composite Blade Track with Clip Shim Thermal Expansion

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Solution Overview

Problem

Turbine shroud components in gas turbine engines experience differential thermal expansion due to varying coefficients of thermal expansion, leading to misalignment and operational issues when traditional coupling methods are used.

Innovation Solution

A turbine shroud assembly comprising a metallic carrier assembly, a ceramic matrix composite blade track segment, and a retainer with a clip shim that provides a spring force to clamp the blade track segment onto a chordal seal, allowing for axial movement and accommodating thermal expansion differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional coupling methods are used to attach blade track segment to carrier assembly, then structural integrity is maintained, but thermal expansion differences cause misalignment and operational issues

Engineering Contradiction:

Improveoperational reliabilityVSAvoidalignment precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The retainer is designed with flexible arms that can dynamically adjust their position to accommodate thermal expansion and contraction of the blade track segment. This dynamic capability allows the coupling mechanism to maintain proper alignment throughout temperature cycles, resolving the contradiction between structural integrity and alignment precision under thermal stress.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The coupling mechanism incorporates elements with different coefficients of thermal expansion to match the blade track segment and carrier assembly materials. By selecting materials and designs that account for thermal parameter changes, the system maintains alignment precision despite temperature variations, while still providing secure structural coupling.

Inventive Principle:

Principle #35Parameter changes

2Strength

If rigid coupling is used between components, then structural strength is improved, but differential thermal expansion causes misalignment

Engineering Contradiction:

Improvestructural strengthVSAvoidthermal accommodation

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The retainer is divided into multiple segments including a body portion and flexible arms that can move independently. This segmentation allows different parts of the coupling mechanism to respond differently to thermal expansion, maintaining overall structural strength while accommodating dimensional changes in the blade track segment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The retainer incorporates flexible arms with reduced cross-sectional areas that act as compliant elements. These flexible portions can bend and deform to accommodate thermal expansion differences between the blade track segment and carrier assembly, providing thermal accommodation while maintaining secure coupling through the rigid body portions.

Inventive Principle:

Principle #30Flexible shells and thin films

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 effectively manages thermal expansion, ensuring proper alignment and sealing of the turbine shroud assembly, enhancing the operational reliability and efficiency of gas turbine engines by preventing misalignment and maintaining structural integrity under high-temperature conditions.

Implementation Method 1

a retainer with a clip shim that provides a spring force to clamp the blade track segment onto a chordal seal, allowing for axial movement and accommodating thermal expansion differences

Methodology Applied

Scientific EffectSpring force: Spring

Implementation Method 2

Some shrouds positioned in the turbine may be exposed to high temperatures from products of the combustion reaction in the combustor. Such shrouds sometimes include components made from materials that have different coefficients of thermal expansion. Due to the differing coefficients of thermal expansion, the components of some turbine shrouds expand at different rates when exposed to combustion products

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11840936B1Ceramic matrix composite blade track segment with pin-locating shim kit

Publication Date: 2023.12.12 ROLLS ROYCE CORP

AI summary

A turbine shroud assembly includes a carrier assembly, a blade track segment, a retainer, and a clip shim. The carrier assembly is arranged circumferentially at least partway around an axis. The blade track segment is supported by the carrier assembly to locate the blade track segment radially outward of the axis and define a portion of a gas path of the turbine shroud assembly. The retainer extends into the carrier assembly and the blade track segment. The clip shim is located between the carrier assembly and the blade track and configured to urge the blade track segment axially toward the carrier assembly.