Turbine Ring Assembly Cooling via Air Passage Orifices
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Solution Overview
Problem
Existing turbine ring assemblies for turbomachines face challenges in reducing mechanical stresses on metal parts in contact with ceramic matrix composite (CMC) ring sectors, particularly due to exposure to hot flows.
Innovation Solution
The proposed turbine ring assembly incorporates ring sectors made of CMC material with first and second attachment tabs, an annular metal support with flanges, and a first annular metal shroud with air passage orifices to facilitate cooling of metal elements exposed to hot flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CMC ring sectors are used to reduce cooling flow requirements, then turbomachine performance is improved, but metal attachment elements are more exposed to hot flow and subjected to significant mechanical stresses
Solution Approach 1:
The annular support is segmented into multiple radial struts distributed around the circumference, each strut independently supporting the CMC ring sectors. This segmentation distributes the mechanical loads and thermal stresses across multiple discrete elements rather than concentrating them, allowing each strut to be optimized for its specific loading conditions while maintaining overall structural integrity.
Solution Approach 2:
The attachment system uses composite construction combining metal struts with ceramic or thermal barrier coating layers. This composite approach allows the metal portion to provide mechanical strength while the ceramic coating provides thermal protection, reducing the thermal exposure and mechanical stress on the metal attachment elements while maintaining the benefits of CMC ring sectors.
2Reliability
If all metal parts are cooled to withstand hot flows, then structural integrity is maintained, but cooling flow requirements increase and engine performance decreases
Solution Approach 1:
Cooling is applied locally only to the specific metal regions that require it, such as the inner surfaces of the annular support and attachment elements exposed to hot gas flow. The cooling system uses localized cooling channels and impingement cooling zones targeted at high-temperature areas, while allowing other metal portions to operate at higher temperatures without active cooling, thereby reducing overall cooling flow requirements.
Solution Approach 2:
Thermal barrier coatings and ceramic layers are introduced as intermediary materials between the metal attachment elements and the hot gas flow. These intermediate layers provide thermal protection to the metal components, reducing the heat transfer to the metal and allowing it to operate at higher temperatures with reduced or no active cooling, thus maintaining structural integrity while minimizing cooling flow requirements.
3Strength
If metal attachment elements are used to assemble CMC ring sectors, then structural support is provided, but the metal parts are subjected to significant mechanical stresses from hot flow exposure
Solution Approach 1:
The annular support is segmented into multiple radial struts distributed around the circumference, each strut independently supporting the CMC ring sectors. This segmentation distributes the mechanical loads and thermal stresses across multiple discrete elements rather than concentrating them, allowing each strut to be optimized for its specific loading conditions while maintaining overall structural integrity.
Solution Approach 2:
The attachment system uses composite construction combining metal struts with ceramic or thermal barrier coating layers. This composite approach allows the metal portion to provide mechanical strength while the ceramic coating provides thermal protection, reducing the thermal exposure and mechanical stress on the metal attachment elements while maintaining the benefits of CMC ring sectors.
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 configuration effectively cools the metal elements of the ring assembly, reducing mechanical stresses and improving turbomachine performance by minimizing cooling flow requirements and reducing weight.
Implementation Method 1
a first annular metal shroud arranged upstream of the turbine ring and of the first flange, said first shroud comprising an inner periphery in axial abutment toward downstream against the first attachment tab and an outer periphery attached to the first flange
Implementation Method 2
these air passage orifices being configured to provide an air outlet from said cavity
Data Source
AI summary
A turbine ring assembly having ring segments made of ceramic matrix composite material and each having first and second attachment tabs and a cavity for the circulation of air flow, a metal support having a first bracket and a second bracket bearing axially upstream against the second tab, a first metal flange arranged upstream of the first bracket and having an inner periphery bearing axially downstream against the first tab and an outer periphery fastened to the first bracket, and air passage orifices formed in the inner periphery of the first flange and/or in the second bracket, the orifices configured to ensure that the air flow passes from the cavity to the outside of the assembly.