Variable Guide Vane Bushing Assembly for Vibration and Wear Damping
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Solution Overview
Problem
Variable guide vane assemblies in gas turbine engines face issues with vibrations and premature wear due to loose fits between bushings and casings, leading to increased energy losses and potential costly replacements of expensive components.
Innovation Solution
Incorporation of resilient members, such as elastomeric O-rings or C-seals, between the bushings and casings to dampen vibrations and reduce wear by minimizing contact between bushings and peripheral walls, allowing for thermal growth accommodation and tolerance stack-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If loose fits are used between bushings and casings, then ease of assembly and tolerance accommodation are improved, but vibrations and premature wear increase
Solution Approach 1:
A resilient member (such as a rubber or elastomeric ring) is introduced as an intermediary element between the bushing and the casing. This resilient member acts as a mediator that absorbs vibrations and reduces wear while still allowing for tolerance stack-up and thermal growth. The resilient member deforms elastically to accommodate dimensional variations while maintaining a stable connection that prevents excessive movement and wear.
2Reliability
If tight fits are used between bushings and casings, then vibration and wear are reduced, but thermal growth accommodation and tolerance stack-up are compromised
Solution Approach 1:
The resilient member changes its physical parameters (shape, volume, stiffness) in response to thermal growth and tolerance variations. As temperature increases and components expand, the resilient member deforms elastically to accommodate these dimensional changes without creating excessive stress or binding. This allows the assembly to maintain reliable vibration and wear resistance while adapting to thermal and manufacturing variations.
3Reliability
If resilient members are added to dampen vibrations, then reliability is improved, but device complexity increases
Solution Approach 1:
The resilient member is implemented as a flexible ring or O-ring that can be easily installed within the bushing-casing interface. This flexible element provides vibration damping through its elastic properties while maintaining a simple ring geometry that requires minimal assembly steps. The flexible shell design allows the component to be pressed into place and automatically conform to the interface geometry, avoiding complex assembly procedures.
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 reduces vibrations, minimizes wear, and extends the operational range of the compressor section by maintaining a stable fit over a wider thermal range, potentially reducing the need for costly replacements of expensive components.
Implementation Method 1
resilient members disposed radially between surfaces of the first casing and the bushings relative to the spanwise axes, the resilient members in abutment against both of the surfaces of the first casing and the bushings
Implementation Method 2
resilient members... allowing for thermal growth accommodation and tolerance stack-up
Implementation Method 3
minimizes wear by minimizing contact between bushings and peripheral walls
Implementation Method 4
allowing for thermal growth accommodation and tolerance stack-up
Data Source
AI summary
A gas turbine engine, has: an annular gaspath extending around a central axis, the annular gaspath defined between a first casing and a second casing, the first casing defining pockets; and a variable guide vane assembly having: variable guide vanes circumferentially distributed around the central axis, the variable guide vanes having airfoils extending into the annular gaspath and extending between first and second pivot members at respective first and second ends of the airfoils, the variable guide vanes rotatable about respective spanwise axes, bushings received within the pockets of the first casing, the first pivot members of the variable guide vanes rollingly engaged to the bushings, and resilient members disposed radially between surfaces of the first casing and the bushings relative to the spanwise axes, the resilient members in abutment against both of the surfaces of the first casing and the bushings.