Gas Turbine Guide Vane Cover Plate Dovetail Replacement
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Solution Overview
Problem
The existing methods for replacing cover plates in guide vanes of gas turbines are unreliable due to the lack of mechanical withholding after reconditioning, leading to potential brazing connection failures.
Innovation Solution
A guide vane design featuring a dovetail housing with angled sides (50-70°) for the inner platform, allowing for secure mechanical connection and easy replacement of the cover plate through milling cuts, followed by brazing for a reliable attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the cover plate is removed and reinserted into the housing, then the cover plate can be reconditioned and reused, but the mechanical withholding is lost and only brazing connection remains which is unreliable
Solution Approach 1:
The dovetail shape is pre-formed in the housing before cover plate installation. This preliminary geometric configuration ensures that when the cover plate is reinserted after reconditioning, the mechanical interlocking is automatically restored without requiring additional machining operations, thereby maintaining both ease of repair and connection reliability
Solution Approach 2:
The connection system is segmented into two independent components: the dovetail mechanical interlocking structure and the brazing connection. This segmentation allows the mechanical withholding function to be preserved through the dovetail geometry while the brazing provides additional thermal and structural bonding, ensuring reliability even after cover plate removal and reinstallation
2Ease of repair
If the L-shaped sides are milled to remove the cover plate, then the cover plate can be replaced, but the mechanical withholding structure is damaged and cannot withold the cover plate again
Solution Approach 1:
The dovetail housing geometry is pre-configured with sufficient material and structural integrity to accommodate cover plate removal and reinstallation without requiring additional milling operations. The preliminary design ensures that the mechanical strength is preserved through the inherent geometry of the dovetail shape rather than through aggressive material removal
Solution Approach 2:
Instead of treating the L-shaped sides as disposable material to be removed for cover plate replacement, the invention creates a durable, reusable dovetail structure that maintains its mechanical withholding capability throughout the service life of the guide vane, eliminating the need for repeated milling operations
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
Ensures a reliable connection between the inner platform and the cover plate post-reconditioning, maintaining mechanical withholding and preventing brazing connection failures.
Implementation Method 1
the dovetail housing (13) has sides tilted by an angle A being 50-70° with respect to an axis (14) parallel to the gas turbine axis (15)
Implementation Method 2
the cover plate is also connected (usually brazed) to the platform
Data Source
Figure 1~2
Figure 3~4
AI summary
The guide vane (1) of a gas turbine comprises a blade (2) having an outer platform (3) connectable to a guide vane carrier or gas turbine casing (4), and at the opposite end an inner platform (5) that carries a cover plate (7). The inner platform (5) has a dovetail housing (13) to which the cover plate (7) is connected. The method for replacing the cover plate (7) consists in separating the cover plate (7) from the inner platform (5) by cutting along the profile of the dovetail housing (13), then making the cover plate (7) to slide out of the dovetail housing (13), thus inserting a new or refurbished cover plate (7) into the dovetail housing (13).