Blade Outer Air Seal Attachment Block Impingement Cooling
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Solution Overview
Problem
Gas turbine engines face inefficiencies due to leakage of combustion products across turbine blades, which existing blade outer air seals (BOAS) fail to adequately address, leading to reduced engine performance.
Innovation Solution
A blade outer air seal assembly with circumferentially spaced attachment blocks and axial seals, featuring cooling air passage through circumferential gaps and impingement cooling holes, ensures effective sealing and cooling of the turbine blades by directing cooling air radially inwardly and utilizing C-shaped or feather seals to minimize leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If blade outer air seals are spaced radially outwardly of turbine blade tips, then combustion product leakage is minimized, but sealing effectiveness deteriorates due to inadequate cooling and heat management
Solution Approach 1:
The air seal is divided into multiple segments or blocks arranged circumferentially, with gaps between them. This segmentation allows cooling air to pass through the gaps and impinge on the seal surfaces, providing effective cooling while maintaining sealing functionality. Each segment can be independently cooled, improving overall seal reliability without compromising leakage prevention.
Solution Approach 2:
Cooling air is directed through passages and holes in the attachment blocks to impinge on the seal surfaces. This pneumatic cooling system manages heat at the seal interface, preventing thermal degradation that would compromise sealing effectiveness. The controlled airflow through the segmented structure provides both cooling and enhanced sealing contact.
2Temperature
If cooling air is directed through impingement cooling holes at the attachment block, then cooling effectiveness is improved, but device complexity increases due to additional cooling passages and holes
Solution Approach 1:
The attachment block structure serves multiple functions: it provides mechanical support for the seal, contains cooling passages for thermal management, and directs cooling air through impingement holes. By integrating these functions into a single component, the design achieves effective cooling without proportionally increasing overall device complexity. The cooling passages are embedded within the existing structural geometry.
Solution Approach 2:
The cooling function is merged with the structural attachment block rather than being a separate system. The attachment block incorporates both structural support features and cooling passages/holes, combining mechanical and thermal management functions. This integration reduces the number of separate components while achieving effective cooling of the seal interface.
3Use of energy by moving object
If circumferential gaps are provided between adjacent blade outer air seals, then cooling air flow is improved, but sealing continuity deteriorates
Solution Approach 1:
Cooling air acts as an intermediary substance that flows through the circumferential gaps between seal segments. The gaps allow cooling air to pass and impinge on seal surfaces, providing thermal management. The cooling air itself mediates between the need for gap-induced cooling flow and the need to prevent combustion product leakage, as the cooled seals maintain better contact and sealing effectiveness despite the gaps.
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 significantly reduces leakage and enhances the efficiency of gas turbine engines by effectively guiding combustion products across turbine blades, improving engine performance through targeted cooling and sealing mechanisms.
Implementation Method 1
Cooling air after being directed at the central web of the blade outer air seal
Implementation Method 2
cooling air after being directed at the central web of the blade outer air seal, passes radially inwardly through circumferential gaps between adjacent ones of the blade outer air seals
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A gas turbine engine (20) includes a compressor section (24) and a turbine section (28). The turbine section (28) includes at least one turbine rotor having a radially extending turbine blade (102). The turbine section (28) is rotatable about an axis of rotation (A). A blade outer air seal (104) is positioned radially outwardly of a radially outer tip of the at least one turbine blade (102). The blade outer air seal (104) has axially spaced forward and aft portions (106, 108) and a central web (99) between the axially spaced portions (106, 108). An attachment block (110, 136) is supported on structure within the engine (20). The attachment block (110, 136) mounts the blade outer air seal (104). A passage (118) extends into a central chamber (131) within the attachment block (110, 136), and communicates with cooling holes (120) through a radially inner face of the attachment block (110, 136) to direct cooling air at the central web (99) of the blade outer air seal (104).