Inner Ferrule Seal Cavity for Turbomachine Vibration

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Solution Overview

Problem

Existing turbomachine compressor seals, particularly those between the inner shroud and intermediate casing, face challenges due to vibrations, leading to deformation and potential leaks, as they fail to maintain contact pressure and nominal position.

Innovation Solution

An axial turbomachine compressor stator with an internal shroud featuring a cavity to house the seal, where the seal is compressed by inserts and shoulders, providing enhanced sealing and rigidity, and potentially made from composite materials to manage vibrations and deformations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a circular seal is used between the inner ferrule and intermediate housing, then sealing is provided, but the seal deforms radially and axially under vibrations, reducing sealing capacity

Engineering Contradiction:
Improvesealing capacityVSAvoidseal position
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent uses a flexible membrane element that can deform elastically under vibration loads while maintaining sealing contact. The membrane's flexibility allows it to absorb radial and axial vibrations without losing sealing capacity, resolving the contradiction between maintaining seal position stability and accommodating vibration-induced deformations.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The seal system transitions from a static rigid seal to a dynamic flexible membrane that can adapt its shape in response to vibrations. The membrane dynamically adjusts its position and contact pressure during operation, maintaining reliable sealing despite continuous vibrational deformations of the inner ferrule.

Inventive Principle:
Principle #15Dynamics

2Reliability

If a circular seal is used between the inner ferrule and intermediate housing, then sealing is provided, but the seal detaches from the housing, resulting in leaks

Engineering Contradiction:
Improvesealing capacityVSAvoidcontact pressure
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The flexible membrane maintains continuous contact with the housing surface through its elasticity, preventing detachment. The membrane's ability to conform to surface irregularities and maintain contact pressure under vibration ensures reliable sealing without leakage.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The membrane's elastic properties provide a cushioning effect that absorbs vibration energy before it can cause seal detachment. This pre-compliance approach allows the seal to withstand vibration loads without losing contact pressure or detaching from the housing.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Stability of the object's composition

If the seal is made rigid to maintain position, then nominal position is maintained, but the seal cannot accommodate vibrations, reducing sealing effectiveness

Engineering Contradiction:
Improveseal positionVSAvoidsealing capacity
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The flexible membrane provides the ideal balance between position stability and vibration accommodation. While the membrane can deform under vibration, it maintains its overall position and sealing function, unlike rigid seals that either maintain position but fail under vibration or are flexible but lose position control.

Inventive Principle:
Principle #30Flexible shells and thin films

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 the seal against the casing, reduces radial and axial deformations, and improves the structural rigidity of the inner shroud, ensuring reliable sealing and reduced leakage under operational vibrations.

Implementation Method 1

the seal is compressed by inserts and shoulders, providing enhanced sealing

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

potentially made from composite materials to manage vibrations and deformations

Methodology Applied
Scientific EffectVibration damping: Damping

Data Source

PatentEP2886802B1Gasket of the inner ferrule of the last stage of an axial turbomachine compressor
Publication Date: 2019.04.10 SAFRAN AERO BOOSTERS SA
  • EP2886802B1 patent drawingFigure 1~2
  • EP2886802B1 patent drawingFigure 3

AI summary

The invention relates to a downstream compressor stator for an axial turbomachine. The stator comprises an annular row of radially extending blades (26) and an inner ring (30) disposed at the inner ends of the blades (26). The inner ring (30) has a circular seal (36) made of elastomer or silicone, which is positioned at one of the upstream or downstream edges of said ring (30) so as to provide a seal with a sealing surface (44) of the intermediate casing (34) of the turbomachine. The inner ring (30) includes a cavity (45) in which the seal (36) is housed. The cavity is formed entirely within the material of the ring and/or by means of one or more added elements (46). The invention makes it possible to improve sealing in the event of vibrations, while increasing the rigidity of the inner ring (30) without increasing its manufacturing cost. The invention also relates to an axial turbomachine.