Gas Turbine Stator Vane Hook Section Stress Relief
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Solution Overview
Problem
The existing vane arrangements in gas turbines experience heat stress and air leakage issues due to the formation of recessed parts intended to relax stress, which can lead to increased cooling air flow and degraded performance.
Innovation Solution
A vane arrangement with recessed parts in the hook section that reduce stiffness, allowing deformation with heating while maintaining a continuous sealing surface, thereby limiting air leakage and relaxing heat stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a recessed part is formed in the hook section to reduce stress, then heat stress is relaxed, but air leakage increases through the recessed part
Solution Approach 1:
A seal member is introduced as an intermediary element between the recessed part of the hook section and the surrounding structure. The seal member fills the recessed part and prevents air leakage while allowing the hook section to maintain its stress-relieving geometry. This mediator resolves the contradiction by enabling both stress relaxation and leakage prevention simultaneously.
Solution Approach 2:
The hook section is designed with a recessed part that creates local variation in stiffness - the recessed area has lower stiffness to accommodate thermal deformation, while the surrounding areas maintain sufficient stiffness for structural support. When combined with the seal member, this local quality change allows stress relaxation without compromising sealing performance.
2Stability of the object's composition
If the hook protrudes to a large extent in the radial direction to restrict shroud deformation, then shroud stability is improved, but heat stress on the shroud increases
Solution Approach 1:
The hook section's geometric parameters are changed by introducing a recessed part that reduces its stiffness. This parameter change allows the hook to deform more easily under thermal stress, reducing the stress transmitted to the shroud while maintaining sufficient radial protrusion to restrict excessive shroud deformation. The recessed part effectively tunes the mechanical properties of the hook to balance stability and stress reduction.
3Stress or pressure
If the sealing surface is split by the recessed part in the circumferential direction, then stress concentration is reduced, but air leakage increases
Solution Approach 1:
The seal member serves as an intermediary that bridges the gap created by the recessed part in the sealing surface. It maintains circumferential continuity of the sealing function while allowing the underlying hook section to have the stress-relieving recessed geometry. This resolves the contradiction by decoupling the sealing function from the structural geometry.
Solution Approach 2:
The sealing system is segmented into two functional components: the hook section structure with its recessed part for stress management, and the separate seal member for maintaining sealing continuity. This segmentation allows each component to optimize its function independently - the hook section reduces stress concentration while the seal member prevents air leakage.
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 solution effectively reduces heat stress and air leakage, improving the performance and reliability of gas turbines by allowing the hook section to deform without splitting the sealing surface.
Implementation Method 1
allowing deformation with heating
Data Source
Figure 1
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AI summary
A vane (18) has an airfoil section (19) that extends in a radial direction and an outer shroud (20) that is disposed on the radially outward side of the airfoil section (19), and is supported inside a casing by means of a vane support member (24). The outer shroud (20) has a shroud body (31), radial protrusions (36, 37), and a hook section (32) including the radial protrusions (36, 37) and engaging parts (39, 40). A recessed part (50), which is recessed in an axial direction or in the radial direction, is provided in at least a part of the circumference of the hook section (32). The engaging part (39) has a sealing surface that continues along the entire circumference thereof, the sealing surface coming into contact with the vane support member (24) in the radial direction.