CMC Rotor Disk Non-Linear Bore Stress Balance
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Solution Overview
Problem
The challenge lies in manufacturing turbine rotor modules with ceramic matrix composite (CMC) materials, as traditional methods for fastening rotor disks together using bolts and tie rods are not effective, and existing solutions do not adequately address the structural integrity and stress balance in CMC materials under high-temperature, oxidizing gas flow environments.
Innovation Solution
A CMC composite component for gas turbine engines comprising a CMC airfoil and forward and aft CMC platform segments, integrated with a hybrid rotor disk assembly that utilizes a combination of metal alloys and CMC materials, featuring a non-linear bore and airfoil pin design to balance hoop stresses and prevent airfoil roll, while using fasteners and seals to assemble and secure the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metal alloy rotor disks are fastened together using bolts and tie rods, then the structural integrity is maintained under high stress, but the method is not effective when applied to ceramic matrix composite (CMC) materials
Solution Approach 1:
The rotor disk is divided into multiple CMC disks that can be assembled together using interlocking features and retaining rings, eliminating the need for traditional bolts and tie rods. Each disk segment includes integration features that directly connect to adjacent disks, creating a unified structure without external fasteners.
Solution Approach 2:
The connection method transitions from mechanical fastening (bolts and tie rods) to a integrated interlocking system using retaining rings and complementary geometric features. This parameter change in the connection mechanism enables compatibility with CMC materials while maintaining structural integrity under high stress conditions.
2Reliability
If rotor disks are manufactured as single integral pieces, then structural integrity is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The rotor disk is segmented into multiple manufacturable sections that can be produced separately using additive manufacturing or other fabrication processes, then assembled together using integration features. This segmentation reduces manufacturing complexity while maintaining the structural integrity of the complete assembly.
Solution Approach 2:
Multiple separately manufactured CMC disk sections are merged into a unified rotor disk assembly through interlocking integration features and retaining rings. The merging process creates an integral-appearing structure with improved manufacturing feasibility and reduced overall complexity.
3Weight of moving object
If CMC materials are used for rotor disks, then weight is reduced and high-temperature performance is improved, but the challenge of assembling and securing blades to CMC disks arises
Solution Approach 1:
The CMC disk is designed with localized integration features such as firtree slots, platform surfaces, and retaining ring grooves at specific locations where blade attachment is required. These local quality enhancements provide appropriate mechanical interfaces for blade assembly while maintaining the overall weight and high-temperature performance advantages of CMC materials.
Solution Approach 2:
Retaining rings and platform structures serve as intermediary elements between the CMC disk and the blades. These intermediaries provide the necessary mechanical attachment interfaces, making blade assembly to CMC disks as effective as traditional metal alloy disks while preserving the benefits of CMC material usage.
4Adaptability or versatility
If multiple rotor disks are assembled together, then the turbine module functionality is achieved, but ensuring stress balance and preventing airfoil roll becomes challenging
Solution Approach 1:
The integration features including firtree slots and platform geometries are designed with asymmetric characteristics that naturally resist airfoil roll and maintain proper orientation. The asymmetric geometry creates mechanical constraints that prevent unwanted rotation while allowing the assembled turbine module to function properly under operational stresses.
Solution Approach 2:
The integration features are designed with built-in stress-balancing characteristics that counteract centrifugal and aerodynamic forces before they can cause airfoil roll or misalignment. The preliminary design of these features includes geometric constraints and mechanical interlocks that proactively maintain stress balance and airfoil stability during turbine operation.
Data Source
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AI summary
A ceramic matrix composite (CMC) airfoil (66C) for a gas turbine engine (20) includes a CMC root section (66Cr) which extends to form a CMC airfoil section (66C), the CMC root section (66Cr) defines a bore (66CrB) along a non-linear axis (C). A corresponding rotor disk assembly (64C) is also provided.