Gas Turbine Combustion Chamber Segment Fastening
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Solution Overview
Problem
Conventional annular combustion chambers comprising segments face challenges in withstanding ultimate load situations such as compressor surge or combustion chamber flameout, as welding segments together negates the advantages of modular design.
Innovation Solution
A combustion chamber design featuring upstream and downstream ring structures with circumferentially arranged segments, where each segment has integral frame and wall structures, with radially extending holes for secure fastening and thermal expansion accommodation, allowing for removability and differential thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If combustion chamber segments are welded together to withstand ultimate load situations, then the strength and reliability are improved, but the advantages of modular design (ease of repair and replacement) are lost
Solution Approach 1:
The combustion chamber is divided into multiple segments that are removably secured to the upstream ring structure, allowing individual segments to be accessed, removed, and replaced without affecting the entire combustion chamber assembly
Solution Approach 2:
The fastening system transitions from permanent welding to removable fasteners, enabling the combustion chamber segments to be dynamically assembled and disassembled for maintenance while maintaining structural integrity during operation
2Device complexity
If combustion chamber segments are made as integral frame and wall structures, then the manufacturing complexity is reduced, but the ability to accommodate differential thermal expansion is limited
Solution Approach 1:
The frame structure includes locally differentiated features with holes of varying characteristics (circular holes for positioning, slotted holes for thermal expansion accommodation) at different locations to address specific functional requirements
Solution Approach 2:
The frame structure incorporates holes designed to accommodate differential thermal expansion between the combustion chamber segments and the upstream ring structure, allowing the segments to expand and contract freely during operation
3Adaptability or versatility
If multiple types of holes are provided in the frame structure for different purposes, then the functionality is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The hole pattern in the frame structure serves multiple functions simultaneously: circular holes provide circumferential positioning, slotted holes accommodate thermal expansion, and all holes work together with the upstream ring structure to secure and position the combustion chamber segment
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 design effectively manages high radial loads during extreme conditions, allows for differential thermal expansion without inducing stress, and enables easy replacement or repair of segments, maintaining structural integrity and operational efficiency.
Implementation Method 1
to allow relative circumferential thermal expansion between the combustion chamber segment and the upstream ring structure
Data Source
Figure 1
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AI summary
A gas turbine engine combustion chamber (15) comprises upstream and downstream ring structures (43, 54, 56) and a plurality of circumferentially arranged combustion chamber segments (58, 60). Each segment (58, 60) extends the full length of the combustion chamber (15) and each segment (58, 60) is secured to the upstream ring structure (43) and is mounted on the downstream ring structure (54, 56). The upstream end of each combustion chamber segment (58, 60) comprises a surface having a plurality of circumferentially spaced radially extending holes (118) and the upstream ring structure (43A, 43B) having a plurality of circumferentially spaced holes (116A, 116B) extending radially through a portion abutting the surface of the upstream end of each combustion chamber segment (58, 60). Each combustion chamber segment (58, 60) being removably secured to the upstream ring structure (43A, 43B) by a plurality of fasteners (120) locatable in the holes (118) in the combustion chamber segment (58, 60) and corresponding holes (116A, 116B) in the upstream ring structure (43A, 43B).