Ceramic-Matrix Composite Turbine Blade Root Design

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Solution Overview

Problem

The coupling of ceramic-matrix composite blades with metallic disks in gas turbine engines poses design challenges due to heat resistance and centrifugal forces, requiring effective attachment methods that maintain blade positioning during rotation.

Innovation Solution

A turbine wheel design featuring a dovetail slot in the disk and a root with a stem and root casing made of ceramic-matrix materials, where the root core includes woven ceramic fibers or infiltrated foam, and a cooling channel within the blade to manage heat and centrifugal forces, ensuring secure attachment and efficient cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If ceramic-matrix composite blades are coupled with metallic disks, then heat resistance is improved, but attachment reliability deteriorates due to centrifugal forces

Engineering Contradiction:

Improveheat resistanceVSAvoidattachment reliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The blade root is segmented into multiple functional components: a stem extending from the airfoil, a root core containing cooling channels, and a root casing that engages with the dovetail slot. This segmentation allows each component to be optimized for its specific function while collectively solving the attachment challenge under centrifugal forces

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The blade is constructed using ceramic-matrix composite materials that provide both heat resistance and mechanical strength. The composite structure allows the blade to withstand high temperatures from combustion products while maintaining the structural integrity needed to resist centrifugal forces during rotation

Inventive Principle:

Principle #40Composite materials

2Reliability

If a dovetail slot design is used for blade attachment, then blade retention is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveblade retentionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of trying to secure the blade from the front or top, the retention mechanism works from the rear by using centrifugal force to press the root casing against the dovetail slot walls. The design inverts the approach by using the rotational force itself as the retention mechanism rather than relying on mechanical fasteners or complex locking structures

Inventive Principle:

Principle #13The other way round (Inversion)

3Temperature

If cooling channels are added to manage heat, then thermal management is improved, but device complexity increases

Engineering Contradiction:

Improvethermal managementVSAvoiddevice complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The cooling channels are merged into the root core structure itself rather than being separate components. The root core serves dual purposes: providing structural support for the blade attachment and housing the cooling channels that manage thermal loads. This integration reduces overall device complexity while achieving effective thermal management

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10180071B2Composite blades for gas turbine engines

Publication Date: 2019.01.15 ROLLS ROYCE NORTH AMERICAN TECHNOLOGIES INC

AI summary

A turbine wheel for use in a gas turbine engine having a plurality of blades attached to a rotor disk. Each blade is formed as a composite structure including a number of plies of ceramic-containing material. The blades each include a root to fit within dovetail slots of the rotor disk to couple the blades to the rotor disk.