Floating Wall Airfoil Sectors for Turbine Seal Integrity
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Solution Overview
Problem
Gas powered turbines face efficiency reductions due to rope seals being dislodged or lost due to extreme temperature changes, causing fluid leakage through axial joints in the flowpath element assemblies.
Innovation Solution
A floating wall assembly with clamp seals and sectorized design, where each sector includes a concave and convex strut connected via a clamp seal structure, maintaining a foil profile and using fasteners to ensure axial sealing, even under thermal expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rope seals are used along axial joints in flowpath element assemblies, then fluid leakage is prevented under normal conditions, but the seals become dislodged or lost due to thermal expansion and contraction during temperature transitions
Solution Approach 1:
The airfoil assembly is divided into multiple discrete sectors that can independently expand and contract thermally. Each sector is separated by expansion joints that allow relative movement, enabling the structure to accommodate thermal expansion without compromising seal integrity. This segmentation resolves the contradiction by allowing each segment to adapt to temperature changes while maintaining overall sealing through the expansion joint design.
Solution Approach 2:
The expansion joints are designed to change their physical parameters (gap size, orientation) in response to thermal expansion and contraction. During temperature transitions, the joints allow sectors to move relative to each other, maintaining seal contact despite dimensional changes. This parameter adaptation enables the sealing system to remain reliable across varying thermal conditions.
2Ease of manufacture
If flowpath element assemblies are designed as single rigid structures, then manufacturing and assembly are simplified, but thermal expansion causes misalignment and seal failure
Solution Approach 1:
The flowpath element assemblies are segmented into multiple airfoil sectors connected by expansion joints. This segmentation allows each sector to be manufactured and assembled independently, then connected through standardized joint interfaces. The modular approach maintains manufacturing simplicity while enabling thermal adaptation, as each sector can expand and contract independently without affecting the entire assembly.
Solution Approach 2:
The expansion joints introduce dynamic capability to the otherwise rigid flowpath structure. The joints allow controlled movement and adjustment between sectors in response to thermal conditions, transforming the static assembly into a dynamically adaptable system that maintains seal integrity during temperature transitions.
3Reliability
If expansion joints are added to accommodate thermal growth, then seal reliability is maintained during temperature changes, but device complexity increases
Solution Approach 1:
The airfoil assembly is segmented into discrete sectors with expansion joints between them. This segmentation approach manages complexity by localizing the thermal adaptation mechanism to specific joint regions rather than requiring complex mechanisms throughout the entire structure. Each joint is a relatively simple component that allows controlled movement, and the modular sector design enables standardized manufacturing and assembly.
Solution Approach 2:
The expansion joints serve as intermediary elements between adjacent airfoil sectors. These joints mediate the thermal expansion and contraction forces, allowing controlled movement while maintaining seal integrity. By placing the complexity locally at the joint interfaces rather than throughout the entire structure, the overall system complexity is managed effectively.
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 floating wall assembly effectively maintains a seal along the flowpath, preventing fluid leakage and reducing efficiency losses caused by thermal expansion, while accommodating different growth rates of components.
Implementation Method 1
the gasses passing through the flowpath in the turbine section are at extreme temperatures, and can be elevated from ambient temperatures to extreme temperatures, and vice versa, when the engine is initially starting up and when the engine is winding down. The extreme temperature changes result in expansion and contraction of the flowpath element assemblies.
Data Source
Figure 1
Figure 2~3A
Figure 3B
AI summary
A foil assembly for a gas powered turbine includes a plurality of floating wall sectors (210) arranged circumferentially about an axis defined by a flowpath. Each of the floating wall sectors (210) includes a first flowpath strut component (230), a second flowpath strut component (240), a floating wall panel (220) connected to the first flowpath strut component (230) by a first clamp seal at a first axial joint and connected to the second flowpath strut component (240) by a second clamp seal at a second axial joint, and a plurality of leading edge structures (170) fore of the plurality of floating wall sectors (210). Each of the leading edge structures (170) is configured to define a foil profile in conjunction with a first flowpath strut component (230) of a first floating wall sector and an adjacent flowpath strut component (240) of a second floating wall sector (210).