Gas Turbine Blade Trailing-Edge Reconditioning With Pressure-Side Cutout
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Solution Overview
Problem
Existing methods for reconditioning gas turbine blades are time-consuming and costly, often altering the blade profile significantly or requiring extensive material removal and replacement, which is not flexible or efficient.
Innovation Solution
A method involving a cutout in the pressure-side wall along the trailing edge of the blade airfoil, allowing the trailing edge of the suction-side wall to remain unaltered, with the possibility of machining exposed parts from both sides and limited intervention in the cooling system, using electrical discharge machining and optionally inserting a throttling element and coating the surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the trailing edge is removed by EDM and replaced by filling material, then the damaged sections can be repaired, but the reconditioning process becomes very time-consuming and costly
Solution Approach 1:
The blade trailing edge is segmented into a pressure-side wall and a suction-side wall that can be independently processed. The cutout is introduced only into the pressure-side wall, allowing separate repair operations on each wall without requiring complete removal and replacement of the entire trailing edge assembly.
Solution Approach 2:
Instead of removing the entire trailing edge, only the damaged portion of the pressure-side wall is extracted via a cutout. This selective extraction minimizes material removal while providing access for repair operations on the suction-side wall, significantly reducing reconditioning time compared to complete trailing edge removal.
2Ease of repair
If the trailing edge is completely cut away on both suction side and pressure side, then damaged sections can be repaired, but the blade profile is significantly altered
Solution Approach 1:
The cutout is applied locally only to the pressure-side wall where it is most effective for access, while the suction-side wall trailing edge remains intact. This localized modification provides sufficient access for repair operations without significantly altering the overall blade profile, maintaining aerodynamic performance.
Solution Approach 2:
The reconditioning approach applies asymmetric treatment to the two walls: the pressure-side wall receives a cutout for access, while the suction-side wall trailing edge is preserved. This asymmetric strategy achieves repair accessibility while minimizing profile alteration, as the suction-side edge is more critical for aerodynamic performance.
3Shape
If the trailing edge is cut back during production, then a thin airfoil end is achieved, but the cooling system at the trailing edge is altered
Solution Approach 1:
Instead of completely removing the trailing edge or applying excessive material, a partial cutout of controlled depth (at most 15% of chord length) is introduced into the pressure-side wall. This partial action provides access for repair while deliberately limiting the extent of intervention to preserve cooling system integrity and maintain acceptable aerodynamic characteristics.
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 allows for simpler, more flexible reconditioning of gas turbine blades with minimal alteration to the blade profile, reducing costs and time, while maintaining the integrity of the cooling system and enabling deeper crack repairs.
Implementation Method 1
using electrical discharge machining
Data Source
Figure 1~1a
Figure 2
Figure 3
AI summary
The invention features a method for reconditioning a blade (10) of a gas turbine, which blade (10) comprises a blade airfoil (11), with a pressure side (14) and a suction side (15), which extends in the blade longitudinal direction between a platform (18) and a blade tip (17), has a leading edge (12) and a trailing edge (13), and is outwardly delimited by a pressure-side wall (14a) and a suction-side wall (15a) which converge at the trailing edge (13) of the blade airfoil (11), forming discharge openings (21) for cooling air which are arranged in a distributed manner along the trailing edge (13) between the walls (14a, 15a). A reconditioning with comparatively low cost is achieved by a cutout (20) being introduced into the pressure-side wall (14a) along the trailing edge (13), and starting from said trailing edge (13), in such a way that the trailing-side edge of the pressure-side wall (14a) is cut back compared with the trailing-side edge of the suction-side wall (15a).