Gas Turbine Blade Shroud Segment with Segmented Side Rails
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Solution Overview
Problem
Gas turbine blade shroud segments face premature failure due to mechanical stresses, misalignment, and hot gas ingestion caused by inadequate side rail geometry and cooling efficiency, leading to increased deformation and vibration.
Innovation Solution
The blade shroud segment features subdivided side rails with varying heights and widths, inclined fins, and fillets to optimize geometry, enhance stiffness, and improve cooling air flow, with openings for injecting cooling air and Z-shaped edges to minimize dead zones and mechanical loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the wall thickness of the platform is minimized to reduce mechanical stresses, then the mechanical stress resistance is improved, but the alignment precision between adjacent blade shroud segments deteriorates due to manufacturing and assembly tolerances and thermal-mechanical deformations
Solution Approach 1:
The side rail is divided into multiple sections (first side rail section, second side rail section, etc.) with different heights and widths. This segmentation allows each section to be optimized independently - thinner sections where alignment is less critical and thicker sections where structural support is needed, thus resolving the contradiction between minimizing stress and maintaining alignment precision.
Solution Approach 2:
The side rail features non-uniform thickness distribution with different sections having different heights and widths. This local quality variation provides enhanced stiffness and alignment stability in critical regions while maintaining overall thin wall thickness to reduce mechanical stresses, thereby resolving the contradiction between stress resistance and alignment precision.
2Stress or pressure
If the wall thickness of the platform is minimized to reduce mechanical stresses, then the mechanical stress resistance is improved, but the shroud lifetime deteriorates due to hot gas ingestion through mismatches
Solution Approach 1:
The side rail is segmented into multiple sections with varying dimensions, allowing critical regions prone to hot gas ingestion to have enhanced thickness for better sealing and alignment stability, while other regions maintain thin walls for stress reduction. This resolves the contradiction between stress resistance and shroud lifetime.
Solution Approach 2:
The side rail exhibits local quality variations with different heights and widths in different sections. This enables targeted reinforcement in areas where hot gas ingestion risk is highest, preventing premature failure and extending shroud lifetime while maintaining overall low mechanical stress through thin wall design.
3Stability of the object's composition
If the side rail geometry is optimized to improve stiffness and reduce deformation, then the structural stability is improved, but the device complexity increases due to varying heights and widths of side rail sections
Solution Approach 1:
The side rail is divided into discrete sections with different heights and widths, each serving specific structural functions. This segmentation achieves optimized stiffness and reduced deformation in critical areas while keeping the overall design manageable through modular sectioning, thus resolving the contradiction between structural stability and device complexity.
4Stability of the object's composition
If the side rail height and width are increased to improve stiffness, then the structural stability is improved, but the mass of the shroud segment increases
Solution Approach 1:
The side rail features local quality variations with different heights and widths in different sections. This allows stiffness enhancement only in critical regions where structural stability is most needed, while other regions maintain minimal thickness to reduce mass, thereby resolving the contradiction between structural stability and shroud mass.
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 design enhances the structural integrity and cooling efficiency of the shroud segment, reducing deformation, vibration, and hot gas ingestion, thereby extending the shroud's lifespan and maintaining mechanical performance under thermal and mechanical loads.
Implementation Method 1
the blade shroud is cooled by means of a cooling fluid (e.g. cooling air) passing through a cooling system within the platform of the shroud that is fluidly connected to the hollow interior of the blade airfoil
Implementation Method 2
The shroud lifetime is limited by the mechanical stresses caused by centrifugal forces
Data Source
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AI summary
A blade (10) for a gas turbine comprises an airfoil (11), which extends along a longitudinal axis (21) from a blade root (20) to a blade tip (12), and has a shroud segment (14) at said blade tip (12), which shroud segment (14) abuts with first and second edges against similar shroud segments of adjacent blades to make up a ring-like shroud, whereby said first and second edges are each provided with a respective side rail (18,19) on the upper side of said shroud segment (14). To optimize the mechanical and thermal properties of the shroud segment (14), each of said side rails is subdivided into sections (18,19) of different height and/or width.