CMC Vane Baffle for Gas Turbine Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Implementing ceramic matrix composite (CMC) materials in gas turbine engine airfoils is challenging due to unique requirements for high temperature resistance and efficient cooling, particularly in designs where leading edges need effective cooling without intermixing of cooling air streams.
Innovation Solution
A vane design for gas turbine engines featuring a ceramic airfoil section with a support spar and baffle system, where the baffle is formed of sheet metal and mounted on spring members, isolating cooling air streams to provide efficient impingement cooling to the leading edge while maintaining separate passages for different air pressures, enhancing cooling efficiency and thermal shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used in airfoils for high temperature resistance, then temperature capability is improved, but cooling efficiency and thermal management become more challenging
Solution Approach 1:
The cooling system is segmented into distinct zones: a plenum space for receiving cooling air and a separate impingement cooling zone for directing cooled air to the leading edge. This segmentation allows independent optimization of each zone's thermal management strategy.
Solution Approach 2:
Different cooling strategies are applied to different regions of the airfoil. The leading edge receives high-velocity impingement cooling through holes in the baffle, while other regions utilize conventional plenum cooling, allowing localized optimization based on thermal requirements.
2Temperature
If cooling air streams are combined for thermal management, then cooling coverage is improved, but cooling efficiency decreases due to air stream intermixing
Solution Approach 1:
The baffle divides the internal cavity into separate regions, preventing intermixing of different cooling air streams. Fresh cooling air is directed through the baffle to the leading edge while maintaining separation from other thermal zones.
Solution Approach 2:
The baffle acts as an intermediary structure that mediates between the plenum space and the leading edge cooling zone. It receives cooling air and selectively directs it through impingement holes to the leading edge while maintaining flow separation.
3Stability of the object's composition
If a rigid baffle structure is used for thermal shielding, then structural stability is improved, but thermal expansion differences cause stress and reliability issues
Solution Approach 1:
The baffle is mounted on spring members that allow dynamic adjustment and movement. This dynamic mounting accommodates differential thermal expansion between the CMC airfoil and metal baffle, preventing stress buildup while maintaining structural stability.
Solution Approach 2:
The spring-mounted baffle explicitly accounts for thermal expansion differences between materials. The spring mechanism allows the baffle to expand and contract independently, accommodating thermal mismatch between the CMC airfoil structure and metal baffle components.
4Productivity
If multiple cooling passages are created for different air pressures, then cooling efficiency is improved, but device complexity increases
Solution Approach 1:
The baffle serves multiple functions simultaneously: it acts as a thermal shield, a flow divider, a structural support, and a mounting platform for spring members. This multi-functionality reduces overall system complexity despite the presence of multiple cooling passages.
Solution Approach 2:
The baffle combines several cooling functions into a single integrated component. It houses impingement holes for high-pressure cooling while also serving as a divider for lower-pressure plenum cooling, merging multiple cooling strategies into one structure.
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 cools the leading edge of turbine vanes by isolating and directing different air pressures through separate passages, improving cooling efficiency and thermal management, and accommodating thermal expansion differences, thus enhancing the operational lifespan of CMC airfoils.
Implementation Method 1
the plenum space conveys second, different pressurized air that discharges through the impingement holes onto the airfoil wall
Implementation Method 2
the baffle is mounted on a spring member
Data Source
Figure 1~2
Figure 3
AI summary
A vane (60) includes a ceramic airfoil section (62) that has an airfoil wall (63) defining a leading edge (62A), a trailing edge (62b), a pressure side (62c), and a suction side (62d). The ceramic airfoil section (62) has an internal cavity (68). A support spar extends through the internal cavity (68) for supporting the ceramic airfoil section (62). The support spar is spaced from the airfoil wall (63) such that there is a gap (74) there between. The support spar has an internal through-passage (72a) that is fluidly isolated from the gap (74) in the ceramic airfoil section (62). A baffle (76) is disposed in the gap (74) and is spaced apart from the airfoil wall (63) and the support spar so as to divide the gap (74) into a plenum space (74a) between the support spar and the baffle (76) and an impingement space (74b) between the baffle (76) and the airfoil wall (63). The baffle (76) has impingement holes (78) directed toward the airfoil wall (63) that connect the plenum space (74a) and the impingement space (74b).