Blade Outer Air Seal with Partial Restriction for Cooling Distribution
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Solution Overview
Problem
Existing blade outer air seal (BOAS) configurations face challenges in evenly distributing cooling air across the seal, leading to excessive flow in some areas and insufficient flow in others due to pressure gradients, which affects the cooling efficiency.
Innovation Solution
The BOAS configuration is reengineered by dividing the chamber into separate upstream and downstream regions with a partial restriction, using a channel in the baffle plate to create a pressure difference and optimizing the distribution and size of holes to maintain desired pressures and minimize air requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cooling air is fed into a single plenum chamber, then the structure is simple, but the air distribution becomes uneven due to pressure gradients causing excessive flow in some areas and insufficient flow in others
Solution Approach 1:
The single plenum chamber is divided into multiple separate chambers (first plenum chamber and second plenum chamber) that are spatially distributed along the flow direction. Each chamber serves a specific region (inlet region and outlet region respectively), which eliminates the pressure gradient problem in a single large chamber and ensures uniform air distribution to different areas of the blade outer air seal.
2Reliability
If the number of cooling outlets is increased to improve cooling coverage, then the cooling effectiveness improves, but the air consumption increases
Solution Approach 1:
Different regions of the blade outer air seal are provided with different numbers and distributions of cooling outlets based on their specific cooling requirements. The inlet region and outlet region have differentiated outlet configurations, allowing optimized cooling effectiveness in each zone while minimizing overall air consumption by matching supply to actual local needs.
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
This approach ensures effective cooling by maintaining pressures above the highest pressure outlets in each region, reducing air consumption and preventing rubbing issues, while allowing for efficient impingement cooling without altering the wax pattern or increasing costs.
Implementation Method 1
The cooling air may pass through passageways in the seal body and exit outlet ports in the inboard or inner diameter (ID) side of the body (e.g. to film cool the ID face)
Implementation Method 2
Air may also exit along the circumferential ends (matefaces) of the BOAS so as to be vented into the adjacent inter-segment region (e.g., to help cool feather seal segments sealing the adjacent BOAS segments)
Implementation Method 3
At least one of the base portion and cover plate comprises a protruding portion protruding into the cavity to form a partial restriction separating forward and aft cavity portions
Data Source
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AI summary
A turbine engine blade outer air seal segment (20) has a body (22) having a base portion (50). The base portion (50) has a transversely concave ID face (32), a forward end (24), an aft end (26), and first and second circumferential edges (28, 30). The body (22) has at least one mounting hook (42). At least one cover plate (60) is secured to the body (22) to define at least one cavity (92). The cover plate (60) has a plurality of feed holes (64). A plurality of outlet holes (70) extend through the base portion (50) to the ID face (32). At least one of the base portion (50) and cover plate (60) comprises a protruding portion (130) protruding into the cavity (92) to form a partial restriction (124) separating forward and aft cavity portions (120, 122).