Ceramic Composite Turbine Ring Assembly with Enclosed Lugs
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Solution Overview
Problem
Existing turbine ring assemblies using ceramic matrix composite (CMC) materials still require significant cooling gas and are subject to mechanical stresses due to hot expansion and embrittlement, limiting engine performance and reliability.
Innovation Solution
The design incorporates CMC ring sectors with radially extending leg portions and attachment lugs that enclose the metal support structure's lugs, providing thermal decoupling and inclined portions to accommodate differential expansion, reducing mechanical stresses and cooling gas requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CMC ring sectors are used to reduce cooling requirements, then engine performance increases, but metallic attachment parts still require cooling and undergo thermal expansion causing mechanical stress
Solution Approach 1:
The invention divides the attachment structure into multiple segments: the CMC ring sector with its attachment lugs, the metallic ring support structure with attachment tabs, and an elastic damping element. This segmentation allows each component to handle stress differently - the CMC sector provides thermal barrier, the metal structure provides mechanical support, and the elastic element absorbs differential expansion stress, preventing stress concentration on the CMC sectors.
Solution Approach 2:
The elastic damping element is pre-installed between the CMC ring sector and the metallic ring support structure to cushion against future thermal expansion differences. This element anticipates the thermal stress problem by providing a compliant interface that absorbs expansion forces before they can damage the CMC sectors, thereby maintaining reliability while allowing the CMC structure to reduce cooling requirements.
2Strength
If metallic attachment parts are exposed to hot flow, then structural strength is maintained, but significant cooling gas is required and thermal expansion causes embrittlement
Solution Approach 1:
The invention nests the metallic attachment tabs within the protective enclosure of the CMC ring sector attachment lugs. The CMC lugs axially enclose the metal tabs, creating a nested structure where the thermally resistant CMC material shields the metallic components from direct hot flow exposure. This nesting arrangement allows the metal parts to maintain structural strength while significantly reducing their cooling gas requirements since they are thermally decoupled from the hot environment.
Solution Approach 2:
The CMC ring sector attachment lugs serve as an intermediary thermal barrier between the hot flow environment and the metallic attachment tabs. This intermediary structure allows the metal tabs to maintain their structural strength benefits while protecting them from direct thermal exposure, thereby reducing the quantity of cooling gas needed and preventing thermal expansion-induced embrittlement.
3Quantity of substance
If attachment lugs are housed between ring sector lugs for thermal protection, then cooling gas requirements are reduced, but space for thermal expansion is restricted
Solution Approach 1:
The invention introduces dynamic compliance to the attachment system through the elastic damping element. Instead of a rigid fixed-position attachment that would create stress during thermal expansion, the elastic element allows the metallic attachment tabs to move dynamically within the enclosed space. This dynamic adjustment capability enables the system to maintain the thermal protection benefits of housing the tabs between CMC lugs while accommodating thermal expansion through controlled movement, thereby managing mechanical stress.
Solution Approach 2:
The elastic damping element changes the mechanical parameters of the attachment system by introducing compliance and stress absorption capabilities. This parameter change allows the system to transition from a rigid, stress-prone configuration to a compliant one that can accommodate thermal expansion within the confined space, thus reducing mechanical stress while maintaining the thermal protection and reduced cooling gas requirements.
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 reduces the need for cooling gas, minimizes mechanical stresses on CMC sectors, and enhances engine performance by maintaining structural integrity and efficiency.
Implementation Method 1
The CMC ring sector thus provides thermal decoupling between the inner face of the turbine ring and the attachment lugs it encloses
Implementation Method 2
The implementation of such inclined sections advantageously allows the ring sector tabs to slide on the ring support structure's mounting tabs in the event of differential expansion
Data Source
Figure 1~2
Figure 3~5
Figure 4
AI summary
The invention concerns a turbine ring assembly comprising a plurality of ring sectors (1) made from ceramic matrix composite material and a ring support structure (2), each ring sector (1) having a part forming an annular base (5) with an inner face (6) defining the inner face of the turbine ring and an outer face (8) from which at least two parts forming lugs (9a; 9b) extend, the ring support structure (2) comprising at least two attachment lugs (11a; 11b) extending radially, the lugs (9a; 9b) of each ring sector (1) gripping the attachment lugs (11a; 11b) of the ring support structure (2) at least at the inner radial ends (14a; 14b) of said attachment lugs (11a; 11b).