Electroformed Rubstrip with Insulating Layer for Gas Turbine Blade Wear
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Solution Overview
Problem
Components in gas turbine engines, particularly airfoils of blades and vanes, experience wear and damage due to centrifugal forces, leading to aerodynamic inefficiencies and structural compromises, with rubbing between blades and rotors causing further issues.
Innovation Solution
A groove in a disk with a blade retention system, featuring a rub strip and insulating material to minimize damage from galvanic forces and wear, and an electroformed die with a non-conductive strip to facilitate easy removal and reduce rubbing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a blade is retained within a disk using a groove and interference fit, then the blade is securely held in place, but rubbing damage occurs between the blade and disk due to centrifugal forces
Solution Approach 1:
A rub strip is introduced as an intermediary component between the blade and the disk. This rub strip makes contact with the disk instead of the blade, absorbing the rubbing forces and preventing direct damage to the blade while maintaining secure retention through the groove and interference fit mechanism
2Reliability
If dissimilar materials are used for the blade and disk, then wear resistance is improved, but galvanic corrosion occurs due to galvanic forces during rubbing
Solution Approach 1:
An insulating material is introduced as an intermediary between the blade and the rub strip. This insulating layer prevents direct electrical contact between dissimilar materials, blocking galvanic corrosion while allowing the wear-resistant dissimilar material combination to function effectively
Solution Approach 2:
The insulating material is designed as a sacrificial component that can be easily replaced. If degradation occurs, the insulating layer can be removed and replaced without affecting the permanent blade or disk, providing economic protection against galvanic corrosion
3Manufacturing precision
If a complex electroforming process is used to create the rub strip, then the rub strip conforms precisely to the blade root contour, but manufacturing complexity increases
Solution Approach 1:
A die is created that contains a precise copy of the blade root contour. This die is then used in the electroforming process to create the rub strip with the exact required shape. The die acts as a template that transfers the complex geometry without requiring complex tooling or multi-step manufacturing processes
4Strength
If the rub strip is made of a conductive material, then wear resistance is improved, but galvanic forces increase during rubbing with dissimilar materials
Solution Approach 1:
The insulating material serves as an intermediary layer between the conductive rub strip and the blade. This allows the rub strip to maintain its conductive properties for wear resistance while the insulating layer prevents direct galvanic interaction with the dissimilar blade material
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 wear and damage to blades and disks, maintaining aerodynamic efficiency and structural integrity by minimizing rubbing and galvanic reactions, while allowing for efficient assembly and disassembly.
Implementation Method 1
an insulating material is place between the rub strip and the blade for minimizing damaging responses of the blade to galvanic forces created by rubbing of the first material and the second material
Implementation Method 2
a die has an electroforming body having a shape conforming to a portion of a shape of a root of a blade
Data Source
AI summary
A disk made of a first material has a groove in which a blade made of a second material is retained. A strip is placed between the blade and the disk to minimize rubbing damage to the blade and the disk and an insulating material is place between the rub strip and the blade for minimizing damaging responses of the blade to galvanic forces created by rubbing of the first material and the second material.