Blade Outer Air Seal Cooling via Pressure Wall Metering
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Solution Overview
Problem
In gas turbine engines, blade outer air seals (BOAS) face reduced cooling efficiency and shortened lifespan due to seal failures between the BOAS and adjacent vanes, leading to pressure drops that compromise the desired fluid pressure on the radially outward surface.
Innovation Solution
A seal assembly with a pressure wall coupled to the engine case via fluid sealing engagements, featuring a first plenum and a second plenum connected through a metering orifice, maintains desired air pressure on the BOAS even in the event of a leak between the BOAS and downstream vane, ensuring continuous cooling by restricting fluid communication to the metering orifice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal failure occurs between the BOAS and adjacent vane, then the BOAS loses cooling efficiency and useful life is reduced, but the seal assembly complexity increases with additional sealing mechanisms
Solution Approach 1:
The seal assembly is divided into multiple independent sealing interfaces: a first fluid sealing engagement between the pressure wall and engine case, and a second fluid sealing engagement between the pressure wall and downstream vane. This segmentation isolates seal failures to specific locations, preventing complete cooling system failure and maintaining reliability without requiring overly complex integrated sealing mechanisms.
Solution Approach 2:
The pressure wall acts as an intermediary component that couples to both the engine case and downstream vane through separate fluid sealing engagements. This intermediary structure provides stable mounting points and distributes sealing requirements across multiple controlled interfaces, reducing overall assembly complexity while maintaining seal reliability.
2Temperature
If fluid communication is unrestricted between plenums, then pressure drops quickly across the BOAS reducing cooling effect, but restricting flow through a metering orifice increases pressure buildup upstream
Solution Approach 1:
The metering orifice precisely controls the flow parameters between plenums, maintaining an optimal balance between pressure differential and cooling airflow. By adjusting the orifice dimensions, the system achieves sufficient pressure buildup upstream to drive cooling flow through the BOAS while preventing excessive pressure drops that would reduce cooling effectiveness.
Solution Approach 2:
The system uses pneumatic principles with the metering orifice to regulate air flow between plenums. The orifice creates a controlled pressure differential that drives cooling air through the BOAS, utilizing gas flow dynamics to maintain both adequate pressure upstream for cooling drive and sufficient flow rate to sustain the cooling effect.
3Stress or pressure
If the pressure wall is securely coupled to the engine case and downstream vane, then the BOAS maintains desired pressure, but the manufacturing precision requirements increase for the fluid sealing engagements
Solution Approach 1:
The fluid sealing engagements are segmented into separate, standardized interfaces between the pressure wall and each mounting surface (engine case and downstream vane). This segmentation allows each sealing interface to be designed and manufactured independently with controlled precision requirements, making the overall assembly more manufacturable while maintaining pressure maintenance capability.
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 effectively maintains the cooling effect on the BOAS and adjacent vanes by limiting pressure drops across the BOAS, even with seal leaks, thereby extending their useful life and maintaining operational efficiency.
Implementation Method 1
a metering orifice configured to maintain a desired pressure differential across the BOAS
Implementation Method 2
a fluid sealing engagement between the pressure wall and the engine case
Data Source
Figure 1
Figure 2
AI summary
A seal assembly of a gas turbine engine includes a blade outer air seal (112), a downstream vane (114), and a pressure wall (102). The blade outer air seal (112) includes a radially outer surface (115) and the downstream vane (114) is coupled to the blade outer air seal (112) via a fluid sealing engagement (134). The pressure wall (102) is coupled to the blade outer air seal (112) and defines a metering orifice (142). The metering orifice (142) of the pressure wall (102) is configured to meter air flow from a first plenum (122) upstream of the pressure wall (102) to a second plenum (123) downstream of the pressure wall (102). At least a preponderance of the radially outer surface (115) of the blade outer air seal (112) at least partially defines the first plenum (122) and the fluid sealing engagement (134) at least partially defines the second plenum (123).