Gas Turbine Support Assembly Tip Clearance Control

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Solution Overview

Problem

Gas turbine engine efficiency is reduced due to leakage around turbine blades, which is exacerbated by differential radial growth between the blades and the blade outer air seal, leading to undesirable rubbing and clearance issues.

Innovation Solution

A support assembly featuring a circumferential ring of segments with cover plates and retention members, including bayonet attachments and tabs, to control radial growth and maintain optimal clearance between the blade and the blade outer air seal, utilizing a unitary control ring and radially outward supports to manage thermal expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the blade outer air seal is held radially outboard from the rotating blade, then leakage prevention is improved, but the tip clearance becomes difficult to control due to differential radial growth

Engineering Contradiction:

ImproveleakageVSAvoidtip clearance control

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The support assembly is divided into multiple segments (first supports, cover plates, retention members) that can independently accommodate radial growth while maintaining the overall structural integrity and tip clearance control

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design allows for controlled parameter changes in the radial position of the blade outer air seal relative to the blade, accommodating differential thermal expansion while maintaining optimal tip clearance through the segmented support structure

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If the tip clearance is reduced to prevent leakage, then energy efficiency is improved, but the blade may rub on the blade air outer seal which is undesirable

Engineering Contradiction:

ImproveleakageVSAvoidblade rubbing

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The support assembly incorporates dynamic elements that allow the blade outer air seal to move radially with thermal expansion, maintaining optimal tip clearance and preventing blade rubbing while minimizing leakage

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The support assembly acts as an intermediary between the blade and blade outer air seal, accommodating differential radial growth and maintaining proper clearance to prevent direct contact while controlling leakage

Inventive Principle:

Principle #24Intermediary (Mediator)

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 controls radial growth and maintains clearance between the blade and the blade outer air seal, enhancing gas turbine engine efficiency by preventing rubbing and leakage, thereby improving overall engine performance.

Implementation Method 1

the plurality of first supports and the plurality of cover plates control radial growth of the blade outer air seal relative to the blade

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3095966B1Support assembly for a gas turbine engine

Publication Date: 2018.10.03 UNITED TECH CORP

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AI summary

A support assembly (100) for a gas turbine engine (20) includes a control ring (106) that extends about a circumferential axis. A plurality of first supports (104) has a cavity (126) that receives the control ring (106). A plurality of cover plates (108) are attached to the first plurality of supports (104) and enclose the cavity (126).