Gas Turbine Stator Vane Seal Spacer Design
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Solution Overview
Problem
Gas turbine engine stator vanes experience air leakage due to grommet deformation, leading to retention system relaxation and requiring frequent field maintenance to tighten the retention system.
Innovation Solution
A seal spacer comprising a circumferential body with a plastomeric support portion and an elastomeric seal portion is used to create a seal between the engine casing wall and the stator vane head, reducing system relaxation by minimizing elastomer compression set and providing fretting protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grommet is used to seal between the vane and case, then sealing is provided, but the grommet deforms causing retention system relaxation
Solution Approach 1:
The seal spacer is divided into two distinct functional portions: a elastomeric seal portion for sealing and a plastomeric support portion for structural support. This segmentation allows each portion to perform its specific function optimally without the elastomeric material bearing structural loads that would cause deformation and relaxation.
Solution Approach 2:
Different portions of the seal spacer have different material properties tailored to their specific functions: the elastomeric seal portion provides flexibility and sealing, while the plastomeric support portion provides rigidity and load-bearing capability. This local differentiation of material qualities prevents the sealing material from deforming under structural loads.
2Reliability
If the grommet is compressed to seal the gap, then sealing is achieved, but compression set occurs requiring field maintenance
Solution Approach 1:
By separating the sealing function from the support function, the elastomeric seal portion is only subjected to minimal compression for sealing without the additional stress of supporting the vane assembly. This reduces compression set and extends the service life before maintenance is required.
Solution Approach 2:
The plastomeric support portion acts as an intermediary between the vane assembly and the case, bearing the structural loads and preventing direct compression of the elastomeric seal portion. This mediator protects the sealing material from excessive compression that would lead to permanent deformation and frequent maintenance.
3Device complexity
If a single elastomeric grommet is used for both sealing and support, then device complexity is reduced, but the elastomer undergoes excessive compression set
Solution Approach 1:
The seal spacer is segmented into two portions with distinct functions, which increases structural complexity but dramatically improves reliability by preventing excessive compression set. The elastomeric seal portion maintains seal integrity because it is not subjected to the full structural loads that would cause deformation.
Solution Approach 2:
The seal spacer uses a composite structure combining two different polymer materials: an elastomeric material for sealing and a plastomeric material for support. This composite approach leverages the advantages of both materials - the flexibility and sealing capability of elastomers and the rigidity and load-bearing capacity of plastomers - to achieve both device simplicity and high reliability.
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 seal spacer effectively reduces air leakage and minimizes the need for frequent maintenance by maintaining a consistent seal between the casing wall and the stator vane head, preventing system relaxation and ensuring proper vane loading.
Implementation Method 1
the grommet may deform, causing retention system relaxation due to elastomer compression set
Implementation Method 2
a plastomeric support portion and an elastomeric seal portion is used to create a seal between the engine casing wall and the stator vane head
Data Source
AI summary
A seal spacer for a gas turbine engine to provide sealing between a casing wall and a stator vane of the engine. The seal spacer comprises a circumferential body having a slot defined therethrough and configured to receive the stator vane therein. The circumferential body is configured to be disposed between and space apart the engine casing wall from a head of the stator vane when the vane is inserted in the slot and the vane is inserted in the opening in the casing wall. The circumferential body includes a support positioned to be engage and provide a gap between the casing wall and the head when the seal spacer is installed therebetween, and an elastomeric seal portion positioned to engage and compressingly provide sealing the casing wall and the head when the seal spacer is installed therebetween to seal the gap.