Turbomachine Sealing Ring Thermal Plate Integrity
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Solution Overview
Problem
Turbomachine turbine sealing rings face issues with crack initiation and detachment due to high temperature gradients and material expansion differences, leading to reduced mechanical integrity and potential detachment of thermal protection plates.
Innovation Solution
The turbomachine sealing ring design incorporates an annular thermal protection plate with a flat tab inserted into a through-slot in the support sector, enhancing mechanical integrity by brazing both the tab and plate to the support, which limits accidental detachment and stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thermal protection plate is brazed to the support sector, then the mechanical integrity is improved, but crack initiation occurs at the circumferential ends due to temperature gradients and material expansion differences
Solution Approach 1:
The patent extracts the problematic circumferential ends of the plate sector by inserting them into through-slots in the support sector. This removes the plate material from the high-stress circumferential regions where crack initiation occurs, thereby maintaining mechanical integrity while preventing crack propagation.
Solution Approach 2:
The patent applies local quality by concentrating the brazed connection in specific regions rather than along the entire circumferential perimeter. The through-slots create localized brazing zones that avoid the high-stress circumferential ends, providing strength where needed while preventing cracks in critical areas.
2Strength
If the plate sector is brazed along the entire circumferential extent, then the mechanical attachment is strengthened, but stress concentration occurs at the circumferential ends leading to detachment
Solution Approach 1:
The plate sector's circumferential ends are extracted from the brazed joint by inserting them into through-slots in the support sector. This eliminates stress concentration at the circumferential ends while maintaining adequate attachment strength through the remaining brazed areas.
Solution Approach 2:
The through-slots are pre-formed in the support sector to receive the plate sector ends before brazing. This preliminary structural arrangement prevents stress concentration from developing during operation, as the plate ends are already positioned in low-stress regions.
3Temperature
If the plate sector is made continuous across the circumferential extent, then the thermal protection coverage is improved, but the coefficient of expansion difference causes high stresses at the ends
Solution Approach 1:
The patent segments the plate sector by inserting its circumferential ends into through-slots in the support sector. This segmentation allows the plate to maintain thermal protection coverage while creating discrete brazing zones that accommodate thermal expansion differences, reducing thermal stress concentration.
Solution Approach 2:
The patent applies local quality by providing thermal protection through the plate sector while creating localized discontinuities at the circumferential ends. These ends are inserted into through-slots where they can accommodate thermal expansion without generating high stresses, while the rest of the plate maintains continuous thermal protection.
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 improves the mechanical integrity of the thermal protection plate, reducing the risk of detachment and stress concentration, while allowing independent movement of components and concentrating the brazed area in a less stressful, cooler region, thus enhancing the overall performance and lifespan of the turbomachine sealing ring.
Implementation Method 1
each plate sector comprising a flat tab pressed against a face of the corresponding support sector and fixed to this face by brazing
Implementation Method 2
the tab is inserted into a through-slot in the support sector in order to improve its integrity in operation
Implementation Method 3
This coating is for example of the honeycomb type and is intended to rub against outer annular lips on the blades of the wheel to form a labyrinth seal
Implementation Method 4
During operation, the casing of the turbine is exposed to very high temperatures that can affect its life. To limit the impact of these temperatures on the casing, it is known to protect it with heat shields
Data Source
AI summary
A turbomachine sealing ring has an axis of revolution and includes an annular support, an annular coating made of abradable material which is carried by the support, and an annular thermal protection plate which is carried by the support. The ring is divided into sectors and has a plurality of ring sectors disposed circumferentially next to one another about the axis. Each ring sector has a support sector, a coating sector, and a plate sector. Each plate sector ling includes a flat tab that is pressed against a face of the corresponding support sector and is fixed to this face by brazing. The tab is inserted into a through-slot in the support sector in order to improve its integrity in operation.