Flow Path Flex Seal With Air Bifurcation for Thermal Growth
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Solution Overview
Problem
Gas turbine engines face challenges in effectively sealing interfaces between hot flowpath components and cooler frame structures due to significant thermal growth, leading to leakage and wear issues, especially in high-temperature environments, which affects thermal and propulsive efficiencies.
Innovation Solution
A gas turbine engine design incorporating a primary flow path with a cooling air flowpath and a flex seal featuring axial convolutions and bifurcation features to direct airflow, combined with a secondary seal, which reduces windage and ensures efficient sealing and cooling air distribution, even in limited packaging spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigidly attached flex seals are used to eliminate sliding contact and reduce wear, then reliability is improved, but device complexity increases and packaging space requirements increase
Solution Approach 1:
The seal is divided into multiple axial convolutions (typically 3-5) rather than using a single rigid seal element. This segmentation allows the seal to flex and accommodate thermal growth while maintaining sealing contact, reducing both wear and overall design complexity
Solution Approach 2:
The seal transitions from a rigid, static design to a dynamic, flexible design with axial convolutions that can expand and contract with thermal growth. This dynamic capability allows the seal to adapt to temperature changes without compromising sealing effectiveness or requiring excessive packaging space
2Stability of the object's composition
If rigid seal designs are used in high temperature environments, then structural stability is maintained, but material temperature capability is reduced due to stiffness requirements
Solution Approach 1:
The seal uses a flexible bellows structure with axial convolutions that can withstand high temperatures while maintaining structural stability. The flexible design allows thermal expansion without compromising the seal's integrity, enabling operation at temperatures exceeding what rigid materials could tolerate
3Temperature
If cooling air flowpaths are provided in areas with limited packaging space, then thermal management is improved, but seal design space is constrained
Solution Approach 1:
The flex seal with axial convolutions serves multiple functions simultaneously: it provides sealing to prevent leakage, accommodates thermal growth, and acts as a flow path for cooling air. This multi-functionality eliminates the need for separate cooling passages, maximizing thermal management efficiency within limited packaging space
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 solution enhances thermal management and reduces leakage by accommodating thermal growth while maintaining efficient airflow bifurcation, improving engine performance and efficiency.
Implementation Method 1
there may be significant thermal growth between the flowpath fairings and relatively cooler frame structure
Implementation Method 2
flex (aka bellows) seals
Implementation Method 3
the bifurcation feature being configured to direct a portion of an airflow through the first seal into a cooling air passage
Data Source
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AI summary
A gas turbine engine includes a primary flow path (206) fluidly connecting a compressor section, a combustor section and a turbine section. A cooling air flowpath (202) is positioned radially outward of the primary flowpath (206). A first seal (210) spans from an inner diameter (203) of the cooling air flowpath (202) to an outer diameter of the cooling air flowpath (202). The first seal (210) includes at least one axial convolution (212) and a plurality of pass through features (240,242,244,246,248). A second seal (220) and the first seal (210) are configured to direct a portion of an airflow through the first seal (210) into a cooling air passage (226) and to direct another portion of the airflow radially inward of the cooling air passage (226).