Turbine Ring Assembly CMC Thermal Expansion
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Solution Overview
Problem
Turbine ring assemblies using ceramic matrix composite (CMC) materials face mechanical stresses and embrittlement due to hot expansion of metal attachment parts, leading to vibration and sealing issues, and existing solutions fail to effectively accommodate varying axial lengths of CMC ring sectors.
Innovation Solution
A turbine ring assembly design featuring a semi-sectored annular flange with relief ports and inter-sector seals, which accommodates different axial lengths and reduces mechanical stresses through deterministic sector positioning and improved sealing, while allowing deformation under temperature and pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal attachment parts are used to assemble CMC ring sectors, then the assembly is mechanically strong, but the metal parts undergo thermal expansion leading to mechanical stress and embrittlement of CMC sectors
Solution Approach 1:
The patent changes the material parameter of the attachment parts from metal to CMC material, which has a lower coefficient of thermal expansion. This parameter change resolves the thermal expansion mismatch problem while maintaining mechanical strength through proper material selection and design.
Solution Approach 2:
The patent uses composite CMC material for both the ring sectors and attachment parts, creating a homogeneous material system that eliminates differential thermal expansion issues between dissimilar materials (metal and CMC).
2Productivity
If CMC material is used for turbine ring sectors, then cooling requirements are reduced and performance increases, but manufacturing precision and assembly complexity increase due to varying axial lengths
Solution Approach 1:
The patent segments the annular flange into multiple radial sectors that correspond to the CMC ring sectors. Each flange sector can be independently manufactured to accommodate the axial length variations of corresponding ring sectors, eliminating the need for high precision across the entire ring assembly.
Solution Approach 2:
The patent applies local quality by allowing each radial sector of the annular flange to have different axial dimensions tailored to the specific requirements of each CMC ring sector. This localized adaptation resolves the manufacturing precision issue without compromising overall assembly quality.
3Stability of the object's composition
If rigid fixing is used to hold ring sectors in position, then vibration is reduced, but the ability to accommodate thermal deformation is limited
Solution Approach 1:
The patent introduces dynamic characteristics by making the attachment system adjustable rather than rigidly fixed. The attachment parts can be positioned and secured at different axial locations, allowing the system to adapt to thermal deformation while maintaining stability during operation.
Solution Approach 2:
The patent changes the attachment parameter from fixed to adjustable, enabling the attachment parts to be positioned at optimal locations that accommodate thermal expansion and deformation while maintaining secure holding and vibration reduction.
4Measurement precision
If multiple attachment parts are used per ring sector, then positioning precision improves, but assembly complexity and time increase
Solution Approach 1:
The patent makes each attachment part multi-functional by designing it to simultaneously provide positioning, securing, and alignment functions. This universal design reduces the number of separate components needed while maintaining high positioning precision.
Solution Approach 2:
The patent merges multiple functions into single attachment parts, combining positioning features, securing mechanisms, and alignment capabilities into integrated components. This reduces assembly complexity while maintaining precision through functional integration.
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 design maintains each ring sector in a deterministic position, reduces mechanical stresses, improves sealing, and simplifies assembly by accommodating varying axial lengths, thereby enhancing the structural integrity and performance of the turbine ring assembly.
Implementation Method 1
these sectors have different widths, as these widths are affected by manufacturing tolerances
Implementation Method 2
allowing the ring to deform under the effects of temperature increases and pressure variations
Implementation Method 3
improving the seal between the non-stream sector and the stream sector, specifically the seal of the cavity located at the radially upper part of the ring
Implementation Method 4
reduces mechanical stresses through deterministic sector positioning and improved sealing
Data Source
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AI summary
Disclosed is a turbine shroud assembly comprising shroud segments (10) forming a turbine shroud (1) and a shroud support structure (3), each shroud segment (10) having, along a sectional plane defined by an axial direction (DA) and a radial direction (DR) of the shroud (1), a part forming an annular base (12) with, in the radial direction (DR), an inner face (12a) and an outer face (12b) from which first and second projections (14, 16) protrude, said structure (3) comprising a shell (31) from which first and second radial clamps (32, 36) project, between which the first and second projections (14, 16) are maintained. The assembly comprises an annular flange (33) having a first portion (333) and a second portion (334) that is removably secured to the first radial clamp (32).