Gas Turbine Ceramic Bushing Reduces Thermal Gradients
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ceramic matrix composite (CMC) airfoils in gas turbine engines face challenges due to their susceptibility to thermal distress from thermal gradients and stresses, which can be exacerbated by cooling methods intended to maximize durability, as they have lower thermal conductivity and strength compared to superalloys.
Innovation Solution
Incorporating a thermal insulation bushing, which can be metallic or ceramic, with a cylindrical or polygonal tube extending between flanges that bear against the ceramic body, creating a gap to minimize convective cooling and reduce thermal gradients by acting as a convection, insulation, and conductance barrier, thereby maintaining a warmer temperature in critical regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling methods are applied to maximize durability of CMC airfoils, then the durability is improved, but thermal gradients and thermal stresses are exacerbated due to lower thermal conductivity of CMC materials
Solution Approach 1:
The patent applies local quality by implementing a thermal insulation bushing at specific critical locations within the CMC airfoil structure where thermal gradients are most problematic. This localized insulation approach allows different regions of the airfoil to have different thermal characteristics - the insulated region maintains warmer temperatures to reduce thermal gradients, while other regions can be cooled as needed. This resolves the contradiction by providing durability improvement through targeted cooling while preventing excessive thermal gradients through localized insulation.
Solution Approach 2:
The thermal insulation bushing acts as an intermediary element between the cooling system and the CMC airfoil structure. It mediates the thermal interaction by controlling heat transfer in specific regions, allowing the cooling system to function effectively while preventing harmful thermal gradients. The bushing material properties and geometric configuration are designed to optimize this mediating function, enabling the system to achieve both durability and acceptable thermal gradient levels.
2Reliability
If thermal insulation bushing is introduced to reduce thermal gradients, then thermal distress is mitigated, but device complexity increases
Solution Approach 1:
The thermal insulation solution is segmented into discrete bushing components that can be independently manufactured, installed, and replaced. Rather than redesigning the entire airfoil structure, the problem is addressed by adding separate, modular insulation elements at specific locations. This segmentation approach limits the increase in device complexity to only the necessary insulated regions, while the rest of the airfoil structure remains unchanged.
Solution Approach 2:
The thermal insulation bushing is nested within the existing CMC airfoil structure, fitting into pre-defined spaces or cavities. This nesting approach allows the insulation element to be integrated into the existing design without requiring major structural modifications. The bushing is contained within the airfoil's internal geometry, minimizing the increase in overall device complexity while still providing the necessary thermal management functionality.
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 thermal insulation bushing effectively reduces thermal gradients across the flange, enhancing the durability of ceramic matrix composite airfoils by maintaining a warmer temperature in localized regions, thus mitigating thermal distress and improving the longevity of CMC components.
Implementation Method 1
a thermal insulation bushing, which can be metallic or ceramic, with a cylindrical or polygonal tube extending between flanges that bear against the ceramic body, creating a gap to minimize convective cooling and reduce thermal gradients by acting as a convection, insulation, and conductance barrier
Implementation Method 2
creating a gap to minimize convective cooling
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A gas turbine engine (20) article (60) includes a ceramic body (62) that defines a flange (70), first and second cooling passages (72, 74) partitioned from each other by the flange (70), a through-hole (76) in the flange (70) that connects the first and second cooling passages (72, 74), and a thermal insulation bushing (78) that lines the through-hole (76).