CMC Turbine Ring Assembly Mounting on Cross-Member
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Solution Overview
Problem
Aeronautical gas turbine engines face inefficiencies and increased costs due to the use of metallic turbine ring assemblies, which require cooling and deformation under high temperatures, leading to performance issues and complex integration challenges with ceramic matrix composite (CMC) materials.
Innovation Solution
A turbine ring assembly composed of ceramic matrix composite material ring sectors with a simplified ring support structure that eliminates the need for a metal ring support casing, using separate parts for mounting and incorporating an air diffuser and fastening means to directly attach to the turbine casing, reducing weight and cost while compensating for manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal turbine ring assembly is used, then the structural strength is sufficient, but cooling is required which reduces engine performance and increases complexity
Solution Approach 1:
The patent applies composite materials by using a ceramic matrix composite (CMC) turbine ring instead of traditional metal. The CMC ring comprises ceramic fibers embedded in a ceramic matrix, providing both high-temperature resistance and structural strength. This eliminates the need for complex cooling systems while maintaining the required mechanical properties at elevated temperatures.
2Loss of energy
If CMC ring sectors are used, then cooling requirements are reduced, but the number of parts increases and integration becomes more complex
Solution Approach 1:
The patent merges multiple functions into the CMC ring structure itself. The ring sectors include integrated mounting features such as axial bores for retention pins and surfaces for abradable coating, eliminating the need for separate metal support casings and reducing the total number of parts. This integration simplifies assembly while maintaining the low cooling requirements of CMC material.
3Weight of moving object
If CMC ring sectors are used, then density is reduced, but shrink-fitting cannot be applied and thermal expansion behavior differs from metal
Solution Approach 1:
The patent addresses the different thermal expansion behavior of CMC compared to metal by designing the retention system to accommodate CMC's lower thermal expansion coefficient. The retention pins fit into axial bores of the CMC ring sectors, and the assembly allows for the specific thermal expansion characteristics of ceramic materials rather than attempting to apply metal-based shrink-fitting methods.
4Reliability
If a ring support casing is used to hold CMC ring sectors, then the integration is achieved, but weight and cost increase and machining operations are complex
Solution Approach 1:
The patent extracts and eliminates the metal ring support casing from the traditional turbine ring assembly. Instead of using a separate metal casing to hold the CMC ring sectors, the design allows the CMC sectors to be directly retained on the turbine shaft through integrated retention features, removing unnecessary weight and simplifying the structure.
Data Source
AI summary
A turbine ring assembly extending about an axis, includes a plurality of ring sectors made of ceramic matrix composite material forming a turbine ring and a ring support structure held by a turbine casing, each ring sector including a base from which an upstream lug and a downstream lug spaced axially from each other extend radially outwardly, the ring support structure including a spacer having a clamp against which the downstream lug of the ring sectors is held, a first upstream flange against which the upstream lug of the ring sectors is held, and upstream of the first upstream flange, a second upstream flange for absorbing forces against which the first upstream flange is held.