Segmented Inner Shroud Thermal Expansion Sealing
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Solution Overview
Problem
The existing seal between segmented inner shroud segments in turbine engines is complex, heavy, and prone to leaks due to angular gaps, which complicates aerodynamics and maintenance, and does not efficiently reduce clearances during operation.
Innovation Solution
A coaxial assembly with a segmented inner shroud and an outer shroud connected by an annular row of blades, featuring a cooling circuit that heats the outer shroud to reduce circumferential clearances between segments, using composite materials and shape memory blades to deform and seal the gaps automatically under mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sealing structures (platforms of bladed boxes) are used to close angular gaps between segments, then leakage is reduced, but device complexity and weight increase
Solution Approach 1:
The patent removes the complex traditional sealing structures (platforms of bladed boxes) and extracts only the essential sealing function, achieving leakage prevention through thermal expansion of the segmented inner shroud itself rather than additional sealing components
Solution Approach 2:
The segmented inner shroud performs self-sealing through its own thermal expansion during engine operation. The segments automatically close the angular gaps due to differential thermal expansion between the inner shroud and outer housing, eliminating the need for external sealing mechanisms
2Reliability
If traditional sealing structures are used to close angular gaps, then leakage is reduced, but weight increases
Solution Approach 1:
The patent eliminates heavy traditional sealing structures and retains only the essential sealing function through the thermal expansion mechanism of the segmented inner shroud, significantly reducing the weight of the compressor assembly
Solution Approach 2:
The patent changes the physical state and dimensions of the inner shroud segments through thermal expansion. During engine operation, the segments expand radially outward to close the angular gaps, achieving sealing without adding weight through material quantity increases
3Ease of manufacture
If segmented inner shroud with angular gaps is used, then manufacturing and assembly are simplified, but aerodynamic performance deteriorates due to leaks
Solution Approach 1:
The patent dynamically changes the dimensional parameters of the segmented inner shroud through thermal expansion. During engine operation, the segments expand to close angular gaps, eliminating leaks and restoring full aerodynamic efficiency while preserving the manufacturing advantages of segmented construction
Solution Approach 2:
The patent introduces dynamic adaptation to the segmented inner shroud structure. The segments transition from an open configuration during assembly/manufacturing to a closed configuration during operation through thermal expansion, optimizing both manufacturing ease and aerodynamic performance at different stages
4Reliability
If traditional sealing platforms are added to close gaps, then leakage is reduced, but maintenance difficulty increases
Solution Approach 1:
The patent removes complex traditional sealing platforms that are difficult to maintain and inspect. The simplified segmented inner shroud design with thermal expansion sealing provides direct visual and physical access to sealing surfaces, greatly improving maintenance accessibility
Solution Approach 2:
The thermal expansion sealing mechanism is inherently self-diagnosing and self-adjusting. During operation, the automatic closing of angular gaps through thermal expansion provides visible indication of proper sealing function, eliminating the need for complex maintenance procedures required by traditional sealing platforms
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 simplifies the seal, reduces leaks, enhances aerodynamic performance, and optimizes output by automatically closing clearances under increased power, improving reliability and maintenance ease while maintaining lightness and economic production.
Implementation Method 1
a cooling circuit for the drive, wherein the circuit is configured to heat up at least the outer shroud during the operation of the turbine engine such as to circumferentially reduce the circumferential clearances between the segments
Implementation Method 2
using composite materials and shape memory blades to deform and seal the gaps automatically under mechanical stress
Data Source
AI summary
An assembly for a turbojet, wherein the assembly includes an outer shroud and an inner shroud that are concentric, wherein the inner shroud is segmented and includes circumferential clearances between the segments thereof. The assembly additionally includes an annular row of stator vanes connecting the inner shroud to the outer shroud, a drive with a reduction ratio that is intended to be coupled to a fan, and a circuit for cooling and for lubricating the drive. The circuit is configured to heat up at least the outer shroud during the operation of the turbine engine such as to circumferentially reduce the circumferential clearances between the segments.