Gas Turbine Blade Tip Reconditioning Without Brazed Closures
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Solution Overview
Problem
The tip region of gas turbine blades experiences high stresses and inefficient cooling due to damaged brazed closing elements, which are prone to thermo-mechanical fatigue and oxidation, leading to reduced blade performance and high reconditioning failure rates in existing methods.
Innovation Solution
A method involving the removal and rebuilding of portions of the rim, tip wall, and outer wall using electrical discharge machining and additive manufacturing techniques, followed by arc welding to eliminate the need for brazed closing elements, thereby enhancing the structural integrity and cooling efficiency of the blade tip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If brazed closing elements are used to close casting openings and service openings in the blade tip, then the blade can be manufactured with internal cooling paths, but the closing elements are heavily damaged by thermo-mechanical fatigue and oxidation leading to high reconditioning failure rates
Solution Approach 1:
The invention extracts and removes the problematic brazed closing elements from the blade tip structure. By eliminating these vulnerable components that are prone to thermo-mechanical fatigue and oxidation, the solution addresses the reliability issue while maintaining the functionality of closing the openings through alternative means during reconditioning operations.
Solution Approach 2:
The invention changes the operational parameters and approach by using electrical discharge machining (ECM) and additive manufacturing techniques instead of traditional mechanical removal and brazing methods. This parameter change enables direct rebuilding of the tip structure without relying on vulnerable brazed closing elements, thereby improving reliability while maintaining manufacturing capability.
2Ease of repair
If existing reconditioning methods are used to replace damaged closing elements, then the blade can be restored, but the process has high fall-out rate and is not reliable
Solution Approach 1:
The invention replaces traditional mechanical reconditioning methods with electrical discharge machining (ECM) and additive manufacturing technologies. This substitution eliminates the need for mechanical removal of damaged elements and subsequent brazing operations, thereby reducing the fall-out rate and improving the reliability of the reconditioning process while maintaining restoration capability.
Solution Approach 2:
The invention performs preliminary removal of the rim portion before rebuilding the tip structure. This preliminary action creates optimal conditions for the subsequent additive manufacturing process, ensuring proper integration of the rebuilt structure with the existing blade tip and improving overall reconditioning reliability.
3Loss of energy
If the tip region is designed with squealer tip to reduce leakage, then the gap between tip and casing is reduced, but the tip region is still subjected to high stresses and the closing elements are heavily consumed
Solution Approach 1:
The invention changes the material and structural parameters of the tip region by using additive manufacturing to create a rebuilt structure with optimized properties. This enables the maintenance of the squealer tip geometry for leakage reduction while improving the structural integrity and stress resistance of the tip region through advanced manufacturing techniques.
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 method provides a reliable, rapid, and cost-effective reconditioning process that extends the lifespan of gas turbine blades by improving thermal resistance and maintaining efficient cooling, reducing the risk of catastrophic failures and reconditioning failures.
Implementation Method 1
removing at least one first portion of the rim in the proximity of the first casting opening and the first service opening; removing at least one first portion of the tip wall comprising the at least one first casting opening
Implementation Method 2
rebuilding the at least one first portion of the outer wall removed without the at least one first service opening; rebuilding the at least one first portion of the tip wall removed without the at least one first casting opening
Implementation Method 3
followed by arc welding to eliminate the need for brazed closing elements
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method for reconditioning a blade (15) of a gas turbine plant (1); the blade (15) comprising an airfoil (18) extending along a span wise direction (S) from a base (21) to a tip (22); the airfoil (18) comprising an outer wall (23) defining a leading edge (27), a trailing edge (28), a pressure side (24) and a suction side (25); the airfoil (18) enclosing at least one cooling duct (36) extending along the span wise direction (S) and fed, in use, with a cooling fluid; the tip (22) being provided with a tip wall (32) and with a rim (29) following, at least in part, the tip cross sectional profile; the tip wall (32) being provided with at least one first casting opening (42) and the outer wall (23) being provided with at least one first service opening (44) arranged close to the respective first casting opening (42); the first casting opening (42) and the first service opening (44) being closed with a first closing element (43) ; the method comprising the step of • removing at least one first portion of the rim (29) in the proximity of the first casting opening (42) and the first service opening (44); • removing at least one first portion (51a, 51b) of the tip wall (32) comprising the at least one first casting opening (42) and at least one portion (50a, 50b) of the outer wall (23) comprising the at least one first service opening (44); • rebuilding the at least one first portion (50a, 50b) of the outer wall (23) removed without the at least one first service opening (44); • rebuilding the at least one first portion (51a, 51b) of the tip wall (32) removed without the at least one first casting opening (42); • rebuilding the at least one first portion of the rim (29) removed.