Angled Cooling Holes in Turbine Shroud Assemblies for CMC Protection

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Solution Overview

Problem

Ceramic matrix composite components in gas turbine engine shrouds face challenges due to thermal expansion and material properties when coupled with traditional cooling methods, leading to localized high thermal gradients and potential material degradation.

Innovation Solution

A turbine shroud assembly design incorporating a ceramic matrix composite blade track segment coupled with a metallic carrier segment, featuring angled impingement passageways that diffuse cooling air to avoid localized thermal gradients, using a mount system with retainers to secure the segments and a cooling air plenum to distribute cooling air effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional cooling methods are used with ceramic matrix composite components, then cooling is provided, but localized high thermal gradients and material degradation occur

Engineering Contradiction:

Improvethermal gradient distributionVSAvoidmaterial degradation

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The cooling holes are angled at specific angles (e.g., 30-60 degrees relative to the normal of the shroud inner surface) to direct cooling air to specific locations where thermal gradients are most severe. This localized targeting of cooling air addresses the thermal management needs of different regions of the ceramic matrix composite blade track segment with differentiated cooling intensities, preventing both localized overheating and material degradation.

Inventive Principle:

Principle #3Local quality

2Temperature

If ceramic matrix composite materials are used in high temperature zones, then temperature resistance is improved, but thermal expansion and material property challenges arise

Engineering Contradiction:

Improvetemperature resistanceVSAvoidthermal expansion stability

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The shroud assembly combines ceramic matrix composite materials for the blade track segment (which provides high temperature resistance) with metallic materials for the carrier segment (which provides structural support and different thermal expansion characteristics). This composite structure allows each material to be used where its properties are most beneficial, while the interface design accommodates thermal expansion differences between the two material types.

Inventive Principle:

Principle #40Composite materials

3Use of energy by moving object

If cooling air is directed straight through the shroud, then cooling efficiency is improved, but localized high thermal gradients are created

Engineering Contradiction:

Improvecooling efficiencyVSAvoidlocalized thermal gradient

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

Instead of directing cooling air perpendicular to the shroud inner surface (single-dimensional approach), the cooling holes are angled to introduce a circumferential component to the cooling air flow. This two-dimensional flow pattern distributes cooling air across a wider area of the shroud inner surface, reducing concentrated thermal gradients while maintaining overall cooling efficiency.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 design effectively mitigates localized thermal gradients, enhancing the durability and longevity of the shroud assembly by evenly distributing cooling air, thus protecting the ceramic matrix composite components from excessive heat.

Implementation Method 1

The plurality of impingement passageways may extend radially through the outer wall of the carrier segment and may be angled circumferentially relative to the axis so as to allow the cooling air to move circumferentially into an open space of the chamber and diffuse before contacting the shroud wall

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

allow the cooling air to move circumferentially into an open space of the chamber and diffuse before contacting the shroud wall to avoid localized high thermal gradient areas on the shroud wall of the blade track segment

Methodology Applied

Scientific EffectThermal diffusion: Diffusion

Data Source

PatentUS12421862B2Turbine shroud assembly with angled cooling holes

Publication Date: 2025.09.23 ROLLS ROYCE CORP

AI summary

An assembly adapted for use in a gas turbine engine includes a blade track segment, a carrier segment, and a retainer. The blade track segment defines a portion of a gas path of the gas turbine engine. The carrier segment supports the blade track segment to locate the blade track segment radially outward of the axis. The retainer couples the blade track segment to the carrier segment. The carrier segment may include a plurality of impingement passageways to conduct cooling air to the blade track segment.