CMC Blade Outer Air Seal with Transverse Hook Mounting
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Solution Overview
Problem
Existing turbine blade outer air seal technologies face challenges in efficiently mounting ceramic matrix composite (CMC) materials due to thermal and pressure stresses, which limit part life and require extensive machining, and often occupy excessive radial space for mounting.
Innovation Solution
A turbine section with a CMC blade outer air seal assembly featuring a double box arrangement of hooks and passages, allowing for direct mounting to a support structure with reduced machining and minimal radial space, utilizing wear liners and film cooling holes, and constructed from cobalt or CMC materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CMC materials are used for blade outer air seal, then heat resistance and durability are improved, but mounting complexity and machining costs increase due to thermal and pressure stresses
Solution Approach 1:
The air seal assembly is divided into modular segments that can be independently mounted. Each segment includes its own support structure with integrated hooks, allowing the CMC air seal to be installed in sections rather than as a single complex piece, thereby reducing overall mounting complexity while maintaining reliability
Solution Approach 2:
A metallic carrier segment acts as an intermediary between the CMC air seal and the turbine structure. This carrier absorbs and manages thermal and pressure stresses, protecting the CMC material from direct stress exposure and simplifying the mounting process by providing a pre-stressed interface
2Manufacturing precision
If extensive machining is performed on CMC air seal, then precise fit and structural integrity are improved, but manufacturing time and costs increase
Solution Approach 1:
The support structure and carrier segments are pre-fitted with hooks and mounting features before the CMC air seal is installed. This preliminary preparation allows the CMC component to be mounted with minimal machining, as the receiving structures are already configured to accept the air seal in its near-final form, reducing both machining time and costs while maintaining precision
Solution Approach 2:
The design transitions from requiring tight tolerance machining of CMC material to using a modular system where fit precision is achieved through standardized interface parameters. The carrier segments and support structures use controlled clearance fits and thermal expansion compensation, eliminating the need for extensive precision machining of the CMC component itself
3Strength
If traditional mounting structures are used, then structural support is provided, but excessive radial space is occupied
Solution Approach 1:
The support structure is nested within the existing turbine assembly geometry. Hooks are positioned to engage with existing structural features, and the carrier segments are configured to fit within the available radial envelope, providing full structural support while minimizing radial space occupation through space-efficient nesting
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 enables efficient, cost-effective, and stress-distributed mounting of CMC blade outer air seals with reduced failure risk and machining costs, while maintaining structural integrity and flexibility.
Implementation Method 1
a wear liner is arranged between the first and second hooks and the segment
Implementation Method 2
a wear liner is arranged between the first and second hooks and the segment
Implementation Method 3
a film cooling hole extends through the base portion
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A blade outer air seal includes a base portion (124) that extends between a first circumferential side (C1) and a second circumferential side (C2) and from a first axial side (Al) to a second axial side (A2). A first wall (120) is axially spaced from a second wall (122). The first and second walls extend from the base portion (124). The second wall (122) has at least one wall window (132) configured to engage with a support structure. An outer wall (126) is radially spaced from the base portion (124) between the first and second walls (120, 122). The outer wall (124) has at least one outer wall window (130, 131) configured to engage with the support structure.