Variable Stator Vane Assemblies Axial Alignment
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Solution Overview
Problem
Conventional gas turbine engine compressor stator vane assemblies face misalignment issues during bolt replacement, leading to potential aerodynamic excitation and disc post cracking due to the lack of clear alignment indicators.
Innovation Solution
A variable stator vane assembly design featuring inclined engagement faces on the stator vane and corresponding projections on the lever arm, ensuring correct axial orientation and providing a visual indication of proper alignment through the use of off-center holes and retaining bolts, preventing incorrect mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bolt retention method is used for variable stator vanes, then assembly simplicity is maintained, but alignment precision deteriorates leading to misalignment during bolt replacement
Solution Approach 1:
The engagement face and projecting formation are designed to automatically self-align the lever arm with the stator vane during assembly. The inclined engagement face guides the projecting formation into the correct axial orientation, ensuring precise alignment without requiring external alignment tools or complex procedures during bolt replacement.
Solution Approach 2:
The engagement face is designed with an asymmetric inclined surface that only matches the corresponding projecting formation at a specific axial orientation. This asymmetric geometry prevents incorrect mounting by ensuring that the lever arm can only be fully mounted at the correct alignment, while any other orientation results in the lever arm being spaced upwardly and unable to mount.
2Reliability
If misalignment occurs during bolt replacement, then ease of repair is maintained, but reliability deteriorates due to aerodynamic excitation and disc post cracking
Solution Approach 1:
The alignment features automatically guide the lever arm into the correct position during bolt replacement, eliminating the need for complex alignment procedures or specialized tools. The self-aligning mechanism ensures that even during maintenance operations, the correct alignment is achieved without increasing repair complexity.
3Manufacturing precision
If inclined engagement faces are used to ensure alignment, then manufacturing precision is improved, but device complexity increases due to additional geometric features
Solution Approach 1:
The inclined engagement face creates an asymmetric geometric relationship between the lever arm and stator vane that only permits full mounting at the correct axial orientation. This asymmetric design provides precise alignment control through the geometry itself, rather than requiring additional alignment components or complex mechanisms.
Data Source
AI summary
A variable stator vane assembly 10 where two downwardly inclined engagement faces 30 are provided on the top of the stator vane upper stem 14, extending for part of the width thereof. A pair of projections 36 with inwardly inclined surfaces 38 are provided on the underside of the lever arm 16. The surfaces 38 are only engageable with the faces 30 in one axial alignment, and otherwise the lever arm 16 will be raised relative to the stator vane 12 to clearly indicate incorrect mounting thereon.