Ceramic Matrix Composite Blade Track with Metallic Carrier Cooling
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Solution Overview
Problem
Turbine shrouds in gas turbine engines face challenges due to differing coefficients of thermal expansion in materials, leading to misalignment and potential overheating issues during operation.
Innovation Solution
A turbine shroud assembly comprising a ceramic matrix composite blade track segment and a metallic carrier segment with a cooling chamber and impingement passageways to direct cooling air towards the blade track segment, preventing heat transfer and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metallic materials are used in turbine shrouds, then structural strength is maintained, but thermal expansion differences cause misalignment and overheating during operation
Solution Approach 1:
The blade track segment is constructed from ceramic matrix composite materials that combine ceramic fibers with a matrix material, providing both high-temperature resistance and controlled thermal expansion properties. This composite structure allows the blade track to maintain structural integrity while experiencing different thermal expansion characteristics compared to traditional metallic shrouds, thereby preventing misalignment and overheating issues.
2Stability of the object's composition
If ceramic matrix composite materials are used in the blade track, then thermal expansion management is improved, but heat transfer to the carrier segment increases
Solution Approach 1:
A carrier segment is introduced as an intermediary component between the ceramic blade track and the metallic shroud structure. This carrier segment absorbs and isolates thermal energy, preventing direct heat transfer from the ceramic blade track to the metallic components. The carrier acts as a thermal buffer, maintaining the stability of the ceramic composite while protecting the metallic structure from excessive heat.
Solution Approach 2:
The heat transfer pathway is extracted and separated from the primary structural connection. By introducing the carrier segment as a distinct intermediate component, the thermal energy is diverted and managed separately from the mechanical load path, allowing the ceramic blade track to maintain its thermal expansion stability without directly transferring heat to the metallic shroud.
3Temperature
If cooling air is directed at the blade track segment, then temperature control is improved, but device complexity increases
Solution Approach 1:
The cooling system is designed to utilize the existing gas path airflow within the turbine engine. Cooling air is drawn from the compressor outlet and directed through the turbine stages, where it naturally flows across the blade track segment and carrier segment. This self-service approach uses the engine's own operational airflow for cooling purposes, eliminating the need for separate cooling fans or complex external cooling systems.
Solution Approach 2:
The gas path airflow serves multiple functions simultaneously: it drives the turbine blades to generate power, cools the ceramic blade track segment, and cools the carrier segment. By designing the cooling passages to align with the natural gas flow path, the same airflow performs both work extraction and thermal management functions, reducing overall system complexity.
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 effectively manages thermal expansion and reduces heat transfer, enhancing the durability and performance of turbine shroud components by maintaining optimal temperature and structural alignment.
Implementation Method 1
The impingement passageways may be in fluid communication with the cooling chamber such that cooling air conducted into the cooling chamber is directed toward the blade track segment to cool the blade track segment during operation of the gas turbine engine
Data Source
AI summary
A turbine shroud assembly for use with a gas turbine engine includes a blade track assembly and a carrier assembly. The blade track assembly includes a blade track segment made of ceramic matrix composite materials and arranged to define a portion of a path of the turbine shroud assembly. The carrier assembly includes a carrier segment made of metallic materials that supports the blade track segment to locate the blade track segment radially outward of the axis.