Hydrostatic Face Seal with Integrated Backup for Gas Turbines

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Solution Overview

Problem

Labyrinth seals in gas turbine engines deteriorate over time due to thermal and mechanical growths, assembly tolerances, and engine loads, leading to increased parasitic losses and thermodynamic cycle losses.

Innovation Solution

Integration of hydrostatic face seals with backup seals, where the backup seal maintains at least a portion of the pressure differential established by the hydrostatic seal in case of failure, using a stator and rotor assembly configuration with a carrier, seal face, and seal runner, and a labyrinth-type backup seal with honeycomb lands and knife edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If labyrinth seals are used in gas turbine engines, then initial sealing performance is achieved, but reliability deteriorates over time due to thermal and mechanical growths, assembly tolerances, and engine loads

Engineering Contradiction:

Improveseal reliabilityVSAvoidseal service life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The backup seal is pre-installed in the seal assembly, positioned to automatically engage when the primary labyrinth seal fails. This preliminary preparation ensures that no additional action is needed at the moment of failure, immediately maintaining the pressure differential and preventing catastrophic engine damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The backup seal serves as a pre-positioned protective measure that cushions against the harmful effects of primary seal failure. By having the backup seal ready in advance, the system prevents the adverse consequences of gas leakage and maintains operational integrity during extended service intervals.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Loss of energy

If seals are used to maintain pressure differentials, then parasitic losses are reduced, but manufacturing precision requirements increase due to assembly tolerances

Engineering Contradiction:

Improveparasitic lossesVSAvoidassembly tolerances

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The invention transitions from relying solely on precise geometric tolerances of the labyrinth seal to a system where the backup seal provides a more tolerant sealing mechanism. The backup seal's design allows for greater assembly tolerance while maintaining effective pressure differential, thereby reducing parasitic losses without requiring ultra-precise manufacturing.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If backup seals are integrated with hydrostatic seals, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improveseal system reliabilityVSAvoidseal assembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The backup seal is integrated into the same carrier structure as the primary hydrostatic seal, combining multiple sealing functions into a single unified assembly. This merging approach maintains reliability through redundancy while avoiding the complexity of separate, independent seal systems. The compact integration ensures that the backup seal adds minimal structural complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The seal assembly is designed to perform multiple functions: the primary hydrostatic seal provides high-performance sealing during normal operation, while the integrated backup seal provides emergency sealing capability. This multi-functionality ensures that a single assembly can handle both routine and failure conditions, improving reliability without proportionally increasing complexity.

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

The solution effectively maintains pressure differentials in gas turbine engines, reducing parasitic losses and thermodynamic cycle losses by switching to the backup seal when the primary hydrostatic seal fails, ensuring continuous operation and minimizing damage from unintended contact.

Implementation Method 1

a hydrostatic seal having a seal face and a seal runner; interaction of the seal face and the seal runner maintains a pressure differential within the gas turbine engine

Methodology Applied

Scientific EffectHydrostatic pressure balancing: Hydraulic Press

Implementation Method 2

the back-up seal maintains at least a portion of a pressure differential established by the first seal prior to the failure

Methodology Applied

Scientific EffectLabyrinth seal resistance: Friction

Data Source

PatentUS8105021B2Gas turbine engine systems involving hydrostatic face seals with integrated back-up seals

Publication Date: 2012.01.31 RTX CORP

AI summary

Gas turbine engine systems involving hydrostatic face seals with integrated back-up seals are provided. In this regard, a representative seal assembly for a gas turbine engine includes: a stator assembly and a rotor assembly configured to operatively engage each other to form a first seal and a second seal; the first seal being provided by a hydrostatic seal having a seal face and a seal runner; and the second seal being provided by a back-up seal such that responsive to a failure of the first seal, the back-up seal maintains at least a portion of a pressure differential established by the first seal prior to the failure.