Turbine Blade Shim Interference Fit Rivet Assembly
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Solution Overview
Problem
In gas turbine engines, compressor blades can loosen and shift within their grooves, leading to increased wear, stress, and potential failure, while shims used to secure them can wear down and protrude into the fluid flow path, disrupting efficiency and causing damage.
Innovation Solution
A blade assembly that includes a shim secured to the blade using a rivet with an interference fit, which is then inserted into a T-shaped channel in the casing, reducing movement and wear by maintaining a consistent clearance and preventing shims from entering the fluid flow path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If shims are used to secure blades and reduce clearance, then blade movement is reduced, but shims wear down and protrude into the fluid flow path
Solution Approach 1:
The shim design incorporates tabs that extend radially outward beyond the blade base, utilizing the radial dimension to engage with the casing groove and prevent axial movement. This dimensional extension allows the shim to maintain blade stability without protruding into the fluid flow path, as the tabs are positioned in the radial clearance space rather than the axial flow path.
Solution Approach 2:
The shim acts as an intermediary component between the blade and the casing, providing a wear surface that protects the blade while maintaining precise positioning. The shim's tabs engage with the casing groove to prevent both blade and shim movement, eliminating the need for the shim to protrude into the flow path for stability.
2Reliability
If shim tabs are used to secure shims in position, then shims are retained in the groove, but tabs wear and loosen the shim from the casing
Solution Approach 1:
The shim material is selected with specific wear-resistant properties and mechanical parameters that exceed those of the blade material. The tab geometry is designed with optimized dimensions and material composition to resist wear from contact with the casing groove, extending the service life of the shim-tab assembly while maintaining reliable retention throughout the component's operational life.
3Stability of the object's composition
If clearance between blade bases is decreased to limit movement, then blade stability improves, but manufacturing precision requirements increase
Solution Approach 1:
The shim assembly with tabs automatically self-adjusts during installation and operation. The tabs engage with the casing groove to precisely position the shim, which in turn positions the blade with the correct clearance. This self-positioning mechanism eliminates the need for high-precision manual clearance control, as the mechanical engagement of the tabs with the groove provides automatic alignment and spacing.
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
This solution reduces blade movement and wear, maintains turbine efficiency, and decreases the frequency of shim and blade replacements by securely fastening shims within the casing, minimizing fluid disruption and component damage.
Implementation Method 1
a shim secured to the blade using a rivet with an interference fit
Data Source
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AI summary
A stator assembly (114) for a turbine engine (100) is provided, that includes a blade (130) with a base (146) including an end wall having at least one hole (220) defined therein and providing a shim (204) having at least one aperture (228) extending therethrough. The shim aperture is aligned with the end wall hole, and the shim is secured to the blade base (146) end wall using a fastener. The fastener is inserted through the shim aperture in an interference fit within the end wall hole. The blade and the shim are coupled to a turbine casing.