CMC Liner Attachment Assembly for Gas Turbine Combustor
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Solution Overview
Problem
Existing gas turbine engines face challenges in robustly and efficiently attaching ceramic matrix composite (CMC) liners to metallic bulkheads due to the brittleness of ceramic materials, which cannot withstand traditional bolt/screw type fasteners, and in radially retaining liner panels while allowing them to thermally expand axially.
Innovation Solution
A combustor liner panel attachment assembly using a radial support with a T-head bolt and a spring element, where the spring element is operatively coupled to a stationary structure, and a protrusion feature extends radially from the liner to be retained within a recessed segment of the spring element, allowing axial retention and thermal growth without the need for threading through the CMC material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional bolt/screw type fasteners are used to attach CMC liners to metallic bulkheads, then the attachment strength is improved, but the CMC liner cracks due to inability to withstand torqueing
Solution Approach 1:
The patent replaces traditional threaded fastener systems with a friction-grip bolt system. The bolt applies clamping force through a nut against a friction surface, eliminating the need for threads in the CMC liner. This substitution of the mechanical connection method prevents cracking while maintaining attachment strength.
Solution Approach 2:
The patent introduces a friction surface as an intermediary element between the bolt/nut assembly and the CMC liner. This friction surface provides the necessary mechanical interface for clamping force transmission without requiring threads in the brittle CMC material, thus protecting the liner from torque-induced cracking.
2Stability of the object's composition
If the liner panel is radially retained to prevent movement, then the positional stability is improved, but the liner panel cannot axially grow due to thermal expansion
Solution Approach 1:
The patent segments the retention function into two independent directions: radial retention through the friction-grip bolt system and axial growth through the unthreaded design. This segmentation allows the liner to be constrained radially while remaining free to expand axially in response to thermal conditions.
Solution Approach 2:
The patent changes the mechanical parameters of the fastening system by eliminating threads and using friction-based clamping. This parameter change allows the liner to maintain radial position stability while accommodating axial thermal expansion, as the friction grip provides radial constraint without axial restriction.
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 solution effectively secures the CMC liners to the bulkhead, preventing cracking and delamination due to thermal expansion, while allowing axial growth, thus enhancing the durability and reliability of the combustor assembly.
Implementation Method 1
the spring element having a recessed segment. The assembly also includes a protrusion feature extending radially outwardly from the first liner, the protrusion feature disposed within the recessed segment of the spring element to axially retain the first liner
Implementation Method 2
a radial support having a shoulder in contact with a radially inner surface of each of the first liner and the second liner to radially retain the first liner and the second liner, the radial support allowing the first liner and the second liner to thermally grow axially
Data Source
AI summary
A combustor liner panel attachment assembly. The assembly includes a first liner extending from a first end to a second end, and circumferentially to partially define a combustion zone. The assembly also includes a second liner disposed circumferentially adjacent to the first liner. The assembly further includes a radial support having a shoulder in contact with a radially inner surface of each of the first liner and the second liner to radially retain the first liner and the second liner, the radial support allowing the first liner and the second liner to thermally grow axially.