Gas Turbine Shroud Seal Mounting for Heat Conduction

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Solution Overview

Problem

The existing seal mounting arrangements in gas turbine engines hinder conduction heat transfer between circumferentially adjacent shroud segments, leading to premature deterioration of the thin material underneath seal receiving slots due to inadequate cooling.

Innovation Solution

A seal mounting arrangement where radially facing seals are positioned on the outer surface of the shroud segments without seal receiving slots, allowing for continuous conduction heat transfer from the inner gas path surface to the outer back surface, and incorporating axially spaced-apart legs with plenums for cooling air reception, which enhances heat dissipation and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If seal receiving slots are provided in the shroud segments for mounting strip seals, then sealing between adjacent shroud segments is achieved, but conduction heat transfer through the platform is interrupted and the thin material underneath the slots becomes hotter and deteriorates prematurely

Engineering Contradiction:

Improvesealing effectivenessVSAvoidtemperature of platform material under seal region

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The invention extracts the seal receiving slots from the platform and relocates the seal mounting function to the circumferential ends of the shroud segments. This removes the harmful interruption of heat conduction paths while preserving the sealing function through radially facing seals mounted at the segment ends.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The radially facing seals act as intermediaries that provide sealing between adjacent segments without requiring slots in the platform. By positioning these seals at the circumferential ends with radially facing surfaces, the invention mediates between the need for sealing and the need for continuous heat conduction through the platform.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If traditional strip seals are mounted in slots within the platform, then sealing is provided, but the thin lip of material underneath the slot remains hotter and is subject to premature deterioration

Engineering Contradiction:

Improveseal functionVSAvoidservice life of platform material

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The seal mounting function is extracted from the platform body and relocated to the circumferential ends of the segments. This eliminates the creation of thin material lips that are prone to thermal deterioration while maintaining the sealing function through radially facing seals positioned at the segment ends.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of mounting seals within the platform thickness (creating thin lips), the invention inverts the approach by mounting radially facing seals at the circumferential ends with their sealing surfaces facing radially inward. This reverses the geometry to eliminate the thin lip problem while preserving sealing effectiveness.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If seal receiving slots are introduced to prevent leakage, then sealing is improved, but heat conduction path is interrupted requiring additional cooling methods and thermal barrier coatings

Engineering Contradiction:

Improveleakage preventionVSAvoidcooling system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The seal receiving slots are extracted from the platform design and replaced with radially facing seals mounted at the circumferential ends. This elimination of slots preserves continuous heat conduction paths through the platform, avoiding the need for additional cooling methods and thermal barrier coatings while maintaining leakage prevention.

Inventive Principle:

Principle #2Taking out (Extraction)

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 solution facilitates uniform heat diffusion and improved durability by eliminating seal receiving slots, reducing the need for additional cooling methods and thermal barrier coatings, thereby extending the lifespan of the shroud platform material.

Implementation Method 1

providing for a continuous conduction heat transfer path underneath the radially facing seals through the platform from the radially inner gas path surface to the radially outer back surface

Methodology Applied

Scientific EffectConduction heat transfer: Conduction (thermal)

Implementation Method 2

axially spaced-apart front and rear legs defining with said back side of the platform a plenum for receiving cooling air

Methodology Applied

Scientific EffectConvection cooling: Convection

Data Source

PatentUS8684680B2Sealing and cooling at the joint between shroud segments

Publication Date: 2014.04.01 PRATT & WHITNEY CANADA CORP

AI summary

A gas turbine engine shroud includes a plurality of shroud segments disposed circumferentially one adjacent to another to form a full, circumferentially segmented ring about the rotor. The radial seal between each pair of adjacent shroud segments is positioned on the back side of the shroud platform. Cooling underneath the radial seals may be done by conduction heath transfer through the platform of the shroud segments.