Ceramic Turbomachine Shroud with Relief Slots

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Ceramic turbomachine shrouds face challenges in distributing stress effectively due to their brittleness and flaw sensitivity, particularly under extreme operational temperatures, which can lead to uneven stress concentration and potential failure.

Innovation Solution

The introduction of positioning and relief slots in an annular shroud made of ceramic materials, where positioning slots receive support fingers to limit radial movement and relief slots are designed to facilitate stress concentration in higher strength areas, allowing for controlled thermal expansion and reduced machining precision requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If ceramic materials are used for the shroud, then tighter tip clearances and improved efficiency are achieved, but the brittleness and flaw sensitivity of ceramic materials lead to uneven stress concentration and potential failure

Engineering Contradiction:

ImproveefficiencyVSAvoidstress distribution

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The shroud is segmented by introducing positioning slots and relief slots that divide the continuous ceramic structure into sections. These slots allow the shroud to flex and distribute thermal stresses more evenly across the structure, preventing stress concentration in single areas while maintaining the overall integrity and efficiency of the ceramic component

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design changes the physical parameters of the shroud by incorporating slots that alter its mechanical properties. The positioning slots and relief slots create controlled flexibility in the otherwise rigid ceramic structure, allowing it to accommodate thermal expansion and contraction while maintaining tighter tip clearances for improved efficiency

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If positioning slots are added to limit radial movement, then radial positioning is improved, but the complexity of the shroud design increases

Engineering Contradiction:

Improveradial positioningVSAvoidshroud design

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The positioning slots are integrated directly into the shroud structure as segmented features rather than adding separate positioning components. This segmentation approach achieves precise radial positioning through the slot-finger interface while keeping the overall design within the existing shroud geometry, minimizing additional complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The positioning slots serve as an intermediary mechanism between the shroud and the clamp ring fingers. These slots provide a controlled interface that allows precise radial positioning through the interaction with fingers, achieving manufacturing precision without requiring complex machining or additional positioning components

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If relief slots are introduced to distribute stress, then reliability is improved, but the structural integrity of the shroud may be compromised

Engineering Contradiction:

Improvestress distributionVSAvoidstructural integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The relief slots are strategically positioned in areas where stress concentration is most likely to occur, creating local quality changes in the stress distribution pattern. The slots are designed with specific geometries and locations that target high-stress regions while preserving the structural integrity of the overall shroud structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The relief slots convert the potentially harmful effect of stress concentration into a beneficial stress distribution pattern. By intentionally introducing controlled discontinuities at strategic locations, the design channels thermal stresses through predetermined paths that prevent catastrophic failure while maintaining structural integrity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This design effectively distributes stress within the shroud, peaking it in higher strength areas and reducing the risk of failure, while minimizing the need for precise machining, thereby enhancing the durability and efficiency of the turbomachine.

Implementation Method 1

relief slots are designed to facilitate stress concentration in higher strength areas

Methodology Applied

Scientific EffectStress concentration: Fracture Mechanics

Implementation Method 2

positioning slots receive support fingers to limit radial movement of the annular shroud

Methodology Applied

Scientific EffectMechanical constraint: Mechanical Force

Data Source

PatentUS8684689B2Turbomachine shroud

Publication Date: 2014.04.01 HAMILTON SUNDSTRAND CORP

AI summary

An example turbomachine shroud assembly includes an annular shroud configured to receive a rotating component. A radially outer surface of the annular shroud establishes positioning slots and relief slots. The positioning slots are configured to receive a support finger that limits radial movement of the annular shroud. The relief slots are different than the positioning slots.