Compliant Shroud Clearance Control via Diffuser Air

Solution Overview

Problem

Conventional Active Clearance Control (ACC) systems for gas turbine engines require complex and weight-increasing components, result in efficiency penalties by extracting thermal control air, and suffer from lag times due to thermal mass response, which affects engine performance and efficiency.

Innovation Solution

A clearance control system featuring a hanger portion, a shroud portion, and a compliant member that defines an actuation chamber, allowing for radial movement of the shroud portion in response to pressure changes within the chamber, eliminating the need for external thermal control air and reducing lag times by directly using compressed air from the diffuser cavity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional ACC systems use thermal control air from bypass ducts to control casing diameter, then blade tip clearances can be adjusted, but engine weight increases and efficiency is reduced

Engineering Contradiction:

Improveblade tip clearance controlVSAvoidengine efficiency

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The system uses the engine's own compressed air from the diffuser cavity to actuate the clearance control mechanism, eliminating the need to extract thermal control air from the bypass duct. This self-service approach maintains bypass air availability for thrust while achieving clearance control.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The compressed air from the diffuser cavity, which was previously unused or partially used, is now utilized for dual purposes: maintaining the airfoil shape and actuating the clearance control mechanism. This multi-functionality eliminates the need for separate thermal control air extraction.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Manufacturing precision

If conventional ACC systems extract thermal control air from bypass ducts, then clearance control is achieved, but thrust is reduced

Engineering Contradiction:

Improveclearance controlVSAvoidthrust

Core Design Contradiction:

Manufacturing precisionVSPower

Solution Approach 1:

The system uses the engine's own compressed air from the diffuser cavity to actuate the clearance control mechanism, eliminating the need to extract thermal control air from the bypass duct. This self-service approach maintains bypass air availability for thrust while achieving clearance control.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If conventional ACC systems account for thermal masses and thermal expansion, then accurate clearance control is achieved, but response time is delayed

Engineering Contradiction:

Improveclearance control accuracyVSAvoidresponse time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The system replaces thermal-based clearance control with a pneumatic system using compressed air from the diffuser cavity. This substitution eliminates thermal mass inertia and enables instantaneous response to clearance adjustments without the lag times associated with thermal expansion and contraction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If conventional ACC systems use complex valves, panels, and ducts for thermal control air routing, then clearance control is achieved, but device complexity and weight increase

Engineering Contradiction:

Improveclearance controlVSAvoidduct system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the complex ducting, valves, and panels required for thermal control air routing. By using the existing diffuser cavity air supply, the system removes these unnecessary components while maintaining clearance control functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The compressed air from the diffuser cavity, which was previously unused or partially used, is now utilized for dual purposes: maintaining the airfoil shape and actuating the clearance control mechanism. This multi-functionality eliminates the need for separate thermal control air extraction.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enables precise and instantaneous adjustment of blade tip clearances, reducing engine weight, maintaining efficiency, and enhancing performance by eliminating the need for external thermal control air and complex duct systems, thus improving fuel burn and overall engine efficiency.

Implementation Method 1

The shroud portion is moveable along the radial direction in response to a pressure change within the actuation chamber

Methodology Applied

Scientific EffectPressure change: Pressure Increase

Implementation Method 2

a compliant member mechanically coupling the hanger portion with the shroud portion and defining an actuation chamber for receiving a fluid

Methodology Applied

Scientific EffectCompliance: Elasticity

Data Source

PatentUS10851712B2Clearance control device

Publication Date: 2020.12.01 GENERAL ELECTRIC CO

AI summary

A clearance control system includes one or more clearance control devices that include features for controlling the clearances between rotating and stationary components of an engine. In one exemplary aspect, a clearance control device utilizes a fluid to pressurize an actuation chamber defined by a compliant member of the clearance control device. The pressurization of the actuation chamber causes the actuation chamber to expand in a direction that changes the clearance between the stationary and rotating components of the engine.