Axially Retractable Brush Seal for Gas Turbine Wear Reduction

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Solution Overview

Problem

Brush seals in gas turbine engines undergo significant wear due to transient events like startup and shutdown, leading to reduced leakage performance and efficiency, and existing radially retractable seal technologies face issues with large segment gaps and potential contamination.

Innovation Solution

An axially retractable brush seal system with a spring mechanism that positions the seal within a seal slot, allowing it to retract during transient events and engage with the rotating component when pressure differential is established, minimizing wear and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If brush seals are used to reduce air leakage through the gap between stator and rotor, then leakage performance is improved, but wear due to transient events increases

Engineering Contradiction:

Improveair leakageVSAvoidseal wear

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The brush seal system transitions from a static seal to a dynamic one that can change its radial position. The seal is equipped with a retraction mechanism allowing it to move radially inward during transient events and return to its sealing position during steady-state operation, thus adapting to changing operational conditions and reducing wear while maintaining leakage performance.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The seal system takes preliminary action by retracting the brush seal radially inward before or during transient events that cause wear. This preemptive retraction prevents the bristles from contacting the rotor surface during startup, shutdown, or other transient conditions, thereby preventing wear before it occurs.

Inventive Principle:

Principle #9Preliminary anti-action

2Reliability

If radially retractable brush seals are used to limit wear during transient events, then seal lifetime is improved, but segment gaps increase causing additional leakage

Engineering Contradiction:

Improveseal wear resistanceVSAvoidair leakage through segment gaps

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention changes the retraction direction from radial to axial. Instead of moving the seal radially inward (changing radius), the seal is designed to retract axially along the rotor surface. This axial retraction allows the seal to clear the rotor during transient events without creating radial segment gaps, thus preventing both wear and leakage.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention inverts the conventional retraction approach. Rather than retracting radially to avoid wear (which creates leakage gaps), the seal is designed to retract axially parallel to the rotor surface. This inverted approach allows the seal to protect against wear while maintaining radial contact and preventing leakage through the use of axial movement instead of radial movement.

Inventive Principle:

Principle #13The other way round (Inversion)

3Loss of energy

If brush seal clearance is reduced to improve leakage performance, then sealing effectiveness is improved, but wear during transient events increases

Engineering Contradiction:

Improveair leakage through clearanceVSAvoidtransient wear

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The harmful contact between bristles and rotor during transient events is extracted or removed by retracting the seal radially inward. This separates the seal from the rotor surface during wear-causing conditions, eliminating the harmful interaction while preserving the tight clearance configuration for normal operation.

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

The axially retractable brush seal system reduces seal clearances and clearance variations, enhancing the seal's predictability, reliability, and lifetime while maintaining performance and reducing wear during steady-state operations.

Implementation Method 1

a spring positioned axially between the upper flange of seal and the seal slot such that the seal is forced into a retracted position with respect to the rotating component

Methodology Applied

Scientific EffectSpring force: Spring

Implementation Method 2

developing a pressure differential across the brush seal such that the pressure differential forces the brush seal into an engaged position with respect to the rotating component

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentUS9121299B2Axially retractable brush seal system

Publication Date: 2015.09.01 GE INFRASTRUCTURE TECH LLC

AI summary

The present application provides an axially retractable seal system positioned within a seal slot of a stationary component and adjacent to a rotating component. The axially retractable seal system may include a seal with an upper flange positioned within the seal slot and one more bristles extending towards the rotating component and a spring positioned axially between the upper flange of seal and the seal slot such that the seal is forced into a retracted position.