Gas Turbine Stator Platform Groove Sealing Design
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Solution Overview
Problem
Gas turbine engines face inefficiencies due to air leaks between compressor section components, particularly between stator vanes, despite the use of knife edge seals, necessitating a solution to reduce compressed air loss.
Innovation Solution
A stator assembly design featuring a platform with a groove and bridge portion that includes a crack between vanes, allowing for relative movement while minimizing the gap size, formed using electro-discharge machining to enhance sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If knife edge seals are used to prevent compressed air leakage, then sealing efficiency is improved, but air leakage still occurs between vanes
Solution Approach 1:
The platform is segmented into multiple sections: a radially inner side with a groove, a radially outer side, and bridge portions connecting them. This segmentation allows the platform to accommodate relative movement between vanes while maintaining sealing effectiveness, addressing the limitation of conventional knife edge seals that cannot prevent leakage between vanes.
Solution Approach 2:
Different regions of the platform have different properties: the groove region allows for movement accommodation, the bridge portions provide structural connection, and the radially outer side maintains continuity for sealing. This local differentiation enables the platform to simultaneously handle both sealing and relative movement requirements.
2Reliability
If the platform groove extends deeper into the platform thickness, then sealing capability is improved, but structural strength is reduced
Solution Approach 1:
The platform groove extends only partially through the platform thickness (5%-20% as specified), which is sufficient to accommodate the necessary relative movement and maintain sealing capability, while avoiding excessive depth that would compromise structural strength. This partial action achieves the minimum required effectiveness without over-engineering.
3Strength
If the bridge portion is made thicker to increase structural strength, then crack propagation is prevented, but manufacturing precision and sealing are compromised
Solution Approach 1:
Crack initiation sites are intentionally created in the bridge portions during manufacturing, and the bridge thickness is carefully controlled to allow cracks to propagate in a predetermined manner. This preliminary action ensures that cracks develop in controlled locations that maintain sealing effectiveness while accommodating operational loads, rather than allowing uncontrolled crack formation.
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 design effectively reduces air leakage between vanes, improving the overall efficiency of the gas turbine engine by allowing for minimal circumferential gap and promoting crack propagation to accommodate operational loads.
Implementation Method 1
formed using electro-discharge machining to enhance sealing efficiency
Data Source
AI summary
A stator assembly includes a platform located on a radially inner end of a plurality of vanes that connects a first vane to a second vane. There is a platform groove on a radially inner side of the platform between the first vane and the second vane.