Turbine Blade Leading Edge Repair Using Segmented Weld-Free Insert
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Solution Overview
Problem
Current methods for repairing turbine blades, especially those affected by heavy water droplet erosion or corrosion, fail to effectively address the leading edge nearest the shroud without causing heat damage, deformation, and increased brittleness, often requiring costly replacements or heat-damaging welds.
Innovation Solution
A method involving the removal of eroded portions to create a cutout portion along the leading or trailing edge, with an insert welded only at a distance from the shroud or platform, forming a weld-free region to prevent thermal damage and using a hardened material for added protection, which extends beyond the original edge for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If welding is used to attach a replacement leading edge to the airfoil near the shroud, then the leading edge erosion is repaired, but the shroud material becomes brittle and deformed due to high temperatures
Solution Approach 1:
The leading edge replacement is divided into two distinct regions: a weld region where the insert is attached to the airfoil, and a weld-free region extending to the shroud. This segmentation allows welding to be performed only in the lower portion where it is needed for structural attachment, while protecting the shroud material from thermal damage that would cause brittleness and deformation.
Solution Approach 2:
The insert is designed with different functional zones: a lower portion that is welded to the airfoil for structural attachment, and an upper portion that extends into the weld-free region near the shroud without welding. This local differentiation allows the weld region to provide structural repair while the weld-free region preserves the original shroud material characteristics and avoids heat-induced degradation.
2Ease of repair
If the entire shroud is replaced to address the leading edge nearest the shroud, then the leading edge erosion is repaired, but material and machining costs increase
Solution Approach 1:
Instead of replacing the entire shroud assembly, only the eroded leading edge portion is removed and replaced with a separate insert. The healthy shroud material is extracted and preserved, while only the damaged section is addressed through welding an insert to the airfoil body, significantly reducing material consumption and cost.
Solution Approach 2:
The original shroud material that is not affected by erosion is recovered and retained in place, while only the eroded leading edge section is discarded and replaced. This selective replacement approach avoids the waste of functional shroud material and reduces the quantity of new materials required for repair.
3Strength
If conventional welding methods are used to repair the leading edge near the shroud, then structural integrity is restored, but heat-induced deformations and material brittleness occur
Solution Approach 1:
The insert is designed with a predetermined weld-free region that extends to the shroud before welding is performed. This preliminary design configuration ensures that the shroud area is protected from thermal exposure before the welding process begins, preventing heat-induced deformations and material brittleness while still allowing welding in the lower region to restore structural integrity.
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 approach allows for a cost-effective repair that maintains original material characteristics, reduces heat-induced deformations, and extends the operating lifetime of the blade by preventing undesirable heat damage and material brittleness, while providing erosion resistance without the need for replacing the entire shroud or platform.
Implementation Method 1
an insert welded to the cutout portion at a weld region
Data Source
AI summary
The disclosure provides a turbine blade. A turbine blade includes a shroud at a tip of the blade and an airfoil having a leading edge extending between the shroud and a root of the blade; a cutout portion extending at least along the leading edge of the airfoil nearest the shroud; an insert welded to the cutout portion at a weld region; and a weld-free region located between the insert and the cutout portion nearest the shroud.