Variable Vane Shroud Asymmetric Segments Leakage
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Solution Overview
Problem
In gas turbine engines, the existing shroud designs for supporting variable vanes create leakage paths due to aligned circumferential edges between circumferential segments, leading to efficiency losses in air flow over vanes and blades.
Innovation Solution
A shroud design with first and second axial halves comprising circumferentially spaced segments, where the edges between adjacent segments on one half are circumferentially offset from those on the other half, eliminating direct leakage paths across the shroud's axial width, and including alignment and securement structures for securing the halves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the shroud is divided into multiple circumferential segments to accommodate thermal challenges and assembly requirements, then the ease of manufacture and adaptability improve, but leakage paths are created at the aligned circumferential edges between segments
Solution Approach 1:
The patent applies asymmetry by deliberately misaligning the circumferential edges of segments between the first and second axial halves. The edges on the first half are positioned at different circumferential locations than the edges on the second half, creating an asymmetric configuration that blocks leakage paths while preserving the segmented structure's manufacturing advantages.
Solution Approach 2:
The patent resolves the leakage issue by transitioning from a two-dimensional alignment problem to a three-dimensional solution. By offsetting edges in the circumferential dimension across different axial halves, the design creates a multi-dimensional configuration where segments are staggered both axially and circumferentially, eliminating direct leakage paths through the shroud.
2Ease of operation
If circumferential segments are aligned between axial halves, then assembly and alignment are simplified, but direct leakage paths exist across the shroud's axial width
Solution Approach 1:
The patent deliberately introduces asymmetry in the circumferential positioning of segment edges between axial halves. This asymmetric arrangement prevents direct alignment of edges across the axial width, blocking leakage paths while maintaining manageable assembly procedures through the use of alignment and securement structures.
3Adaptability or versatility
If more circumferential segments are used to address thermal challenges, then thermal management and adaptability improve, but the number of edges and potential leakage paths increases
Solution Approach 1:
The patent employs segmentation by dividing the shroud into multiple circumferential segments within each axial half, allowing independent thermal expansion and contraction. This segmentation provides thermal management flexibility and adaptability while the staggered configuration manages the complexity of multiple edges.
Solution Approach 2:
The patent reduces the effective complexity of multiple edges by utilizing the third dimension (axial direction) to stagger segment positions. Instead of having all edges aligned in a single circumferential plane, the design distributes edges across different axial and circumferential positions, transforming a potentially complex two-dimensional alignment issue into a more manageable three-dimensional configuration.
Data Source
AI summary
A shroud supports one of an inner and an outer trunnion on a variable vane. The shroud is provided by a first and a second axial half. Each of the axial halves is provided by a plurality of circumferentially spaced segments. Circumferential edges are defined on each of the plurality of circumferentially spaced segments. Edges between adjacent ones of the circumferentially spaced segments on the first half are circumferentially offset from the edges on adjacent ones of circumferentially spaced segments of the second half, such that no direct leakage path exists across an axial width of the shroud.