Turbine Disk Platforms With Air Gaps for Thermal Isolation
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Solution Overview
Problem
Gas turbine engines face challenges in designing rotor wheels that can effectively resist the radial movement of hot combustion products towards metallic disks, leading to overheating, as traditional designs struggle to manage thermal transfer and manufacturing complexities with integrated platforms.
Innovation Solution
A turbine wheel design featuring a disk with radially extending lugs and platforms made of ceramic matrix composite materials, where the platform is coupled to the disk lug with a T-shaped configuration and an air gap to minimize thermal transfer, and secured using braze layers or diffusion bonds, allowing for independent platforms that resist hot gas movement and reduce thermal conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the platform is made from metallic materials and directly coupled to the disk, then the structural strength is improved, but thermal transfer from hot gases to the disk increases causing overheating
Solution Approach 1:
The platform is segmented into multiple sections with transverse partitions creating longitudinal passages. This segmentation allows cooling air to flow through the platform structure, providing internal cooling pathways that reduce thermal transfer to the disk while maintaining structural integrity through the distributed partition design
Solution Approach 2:
Cooling air acts as an intermediary substance that absorbs heat from the hot gases before it reaches the disk. The cooling air flows through the longitudinal passages in the platform, creating a thermal barrier that protects the metallic disk from direct thermal exposure while allowing the platform to maintain its load-bearing function
2Temperature
If the platform is made from ceramic matrix composite materials, then thermal resistance is improved, but the ease of manufacture with metallic materials deteriorates
Solution Approach 1:
The platform uses ceramic matrix composite materials that combine the high-temperature resistance of ceramics with the toughness and ductility of composite structures. This allows the platform to withstand direct exposure to hot gases without excessive thermal transfer to the disk, while the composite nature provides manufacturing flexibility and damage tolerance that bridges the gap between ceramic and metallic manufacturing characteristics
3Temperature
If the outer wall is spaced apart from the disk lug to define an air gap, then thermal transfer is minimized, but the structural support strength deteriorates
Solution Approach 1:
The platform is segmented into multiple sections with transverse partitions that create longitudinal passages. This segmentation allows the platform to achieve thermal isolation through the air gaps created by spacing, while the distributed partition structure provides multiple load paths that maintain structural support capability despite the radial spacing from the disk lug
Solution Approach 2:
The platform structure acts as a flexible thermal barrier that can be spaced from the disk lug to create insulating air gaps. The platform's composite construction and partition design allow it to maintain structural integrity and support loads while positioned radially outward from the disk lug, effectively decoupling thermal conduction from structural support functions
4Device complexity
If integrated platforms are used with blades, then device complexity is reduced, but manufacturing precision requirements increase due to thermal management challenges
Solution Approach 1:
The platform is segmented into multiple sections with transverse partitions rather than being a single integrated component. This segmentation simplifies manufacturing by allowing each section to be fabricated and assembled separately, reducing the precision requirements for monolithic construction while still achieving the thermal management goals through the distributed partition design
Solution Approach 2:
The cooling passages and air gap configurations are designed and prepared in advance during the manufacturing process. The transverse partitions and longitudinal passages are formed beforehand, allowing cooling air flow paths to be established before final assembly. This preliminary preparation of thermal management features reduces the precision requirements during final assembly operations
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 effectively prevents hot gas radial movement towards the disk, minimizing thermal transfer and enhancing the durability of the turbine wheel by using ceramic matrix composite materials and strategic air gaps, while simplifying manufacturing by separating platforms from blades.
Implementation Method 1
The outer wall may be spaced apart radially from the disk lug to define an air gap between the outer wall and the disk lug to minimize thermal transfer between the platform and the disk
Implementation Method 2
the blades may be made from ceramic matrix composite materials that are able to interact with the hot combustion products
Data Source
AI summary
A disk assembly for use in a turbine of a gas turbine engine. The disk assembly includes a disk and a plurality of platforms coupled with the disk. The disk includes a plurality of radially extending disk lugs that define slots for receiving airfoils. The platforms are coupled to the disk lugs between neighboring blades to block radially inward movement of hot gasses toward the disk.