CMC Turbine Ring Assembly Pin-and-Spring Retention
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Solution Overview
Problem
The integration of ceramic matrix composite (CMC) materials in turbine ring assemblies for turbomachines poses challenges due to differences in mechanical behavior and thermal expansion compared to metallic materials, leading to increased complexity, cost, and weight, as well as mechanical stresses and vibration issues.
Innovation Solution
A turbine ring assembly design featuring angular ring sectors made of CMC with a support structure that includes radial and axial pins, a radial spring, and a spacer to provide mechanical support and control positioning, eliminating bolted connections and reducing the number of metal parts, thereby minimizing mechanical stresses and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If CMC ring sectors are used to reduce cooling flow requirements and increase turbine temperature, then turbine performance is improved, but the mechanical behavior differences and thermal expansion characteristics lead to increased assembly complexity and weight
Solution Approach 1:
The turbine ring is divided into multiple CMC ring sectors that are assembled together to form the complete ring. This segmentation allows for easier integration of CMC material while managing the complexity through modular assembly, where each sector can be independently positioned and secured using the pin-and-spring mechanism described in the patent.
Solution Approach 2:
A metal ring support structure serves as an intermediary between the CMC ring sectors and the turbine casing. This intermediary component accommodates the different mechanical behavior and thermal expansion characteristics of CMC material, providing a compatible interface that simplifies the overall assembly process while enabling the performance benefits of CMC.
2Strength
If traditional metal ring support structures with shrink-fit assemblies are used, then structural integrity is maintained, but the mass of the turbomachine increases
Solution Approach 1:
The traditional shrink-fit assembly mechanism is replaced with a pin-and-spring retention system. Transverse pins pass through the CMC ring sectors and the metal ring support structure, while radial springs provide continuous contact and retention force. This substitution eliminates the need for heavy shrink-fit assemblies while maintaining structural integrity through the distributed pin support system.
3Manufacturing precision
If CMC ring sectors are integrated with multiple support parts and complex assembly operations, then positioning control is improved, but the cost and weight of the assembly increase
Solution Approach 1:
The metal ring support structure features localized functional zones: radial flanges for axial positioning, transverse pin holes for radial retention, and spring mounting points for continuous contact. This local quality approach provides precise positioning control at specific critical points rather than through complex overall structures, reducing both cost and weight while maintaining manufacturing precision.
4Reliability
If radial and axial support for CMC ring sectors is provided using traditional metal support techniques, then mechanical stability is ensured, but the number of metal parts increases leading to increased weight and cost
Solution Approach 1:
The radial and axial support functions are merged into a single integrated metal ring support structure. The radial flanges provide axial support while transverse pins passing through the structure provide radial retention. This merging eliminates the need for separate support components, reducing the number of metal parts while ensuring mechanical stability through the combined action of the flanges and pins.
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 reduces the mass and mechanical stresses on CMC ring sectors, simplifies assembly, and enhances sealing and ventilation robustness, while maintaining radial and axial support, thus improving the performance and reliability of turbomachines.
Implementation Method 1
a radial spring, each transverse pin passing through the upstream attachment lug and the downstream attachment lug of the ring sector and the ring support to keep the ring sector and the ring support secured to each other, and the radial spring being kept bearing against the ring sector on the one hand and against the ring support on the other hand
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a turbine ring assembly (2) extending around an axis (X-X), comprising a plurality of ring sectors (10) made of ceramic matrix composite material forming a turbine ring (4) and a ring support structure (6) held by a turbine casing, each ring sector (10) comprising a base (12) from which an upstream latching tab (16) and a downstream latching tab (14) extend radially outwards, spaced apart axially from one another, the assembly (2) further comprising: - a cross-member (20) mechanically connected to the ring support (6) and comprising a first radial flange (210) bearing against the upstream latching tabs (16) of the ring sectors (10), and - for each ring sector (10), at least two transverse pins (40) and a radial spring (70), each transverse pin (40) passing through the upstream latching tab (16) and the downstream latching tab (14) of the ring sector (10) and the ring support (6) in order to keep the ring sector (10) and the ring support (6) rigidly connected to one another, and the radial spring (70) being kept in abutment, in a radial direction (DR) orthogonal to the axial direction (X-X), against the ring sector (10) on the one hand and against the ring support (6) on the other hand in order to keep the ring sectors arranged in the same radial position, the ring support (6) further comprising a second radial flange (68) bearing against the downstream latching tabs (14) of the ring sectors (10), the upstream latching tab (16) and the downstream latching tab (14) of each ring sector (10) being arranged axially between the first radial flange (210) and the second radial flange (68) and said first radial flange (210) comprising a first portion (2103) and a second portion (2104) radially inward of the first portion (2103), the second portion (2104) having a first tab (2105) and a second tab (2106) spaced apart axially from one another and both rigidly connected to the first portion (2103), the first tab (2105) being axially upstream of the second tab (2106), and the second tab (2106) bearing against the upstream latching tab (16).