Gas Turbine Combustion Wall Cooling and Crack Prevention
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Solution Overview
Problem
The existing dual-wall structure combustion chamber design in gas turbine engines faces issues with coolant film discontinuities due to tile rows, leading to increased stress and potential cracking in the annular outer wall, exacerbated by heat conduction through rails and fasteners, which reduces the working life of the combustion chamber.
Innovation Solution
The design incorporates a configuration where the rail of each tile defines slots with the inner surface of the annular outer wall, with fasteners positioned upstream of the rail and apertures arranged upstream of the fasteners to direct coolant onto the tile lips, and grooves in the rail downstream of the fasteners to reduce heat conduction and stress, while maintaining effective cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If apertures are arranged in the annular outer wall to direct coolant onto the lips of tiles, then cooling effectiveness is improved, but the strength of the annular outer wall is reduced and cracks may initiate and propagate
Solution Approach 1:
The patent applies local quality by creating a circumferential region in the annular outer wall that is free from apertures, fasteners, and rails in specific zones. This local modification concentrates cooling apertures in safe regions while preserving wall integrity in vulnerable areas, resolving the contradiction between cooling effectiveness and structural strength.
2Stability of the object's composition
If rails are positioned close to the row of apertures to seal with the annular outer wall, then sealing effectiveness is improved, but heat conduction from tiles to the annular outer wall is increased, exacerbating stress
Solution Approach 1:
The patent segments the annular outer wall into distinct functional zones: a sealing region where rails contact the wall, and a protected circumferential region free from apertures and fasteners. This spatial segmentation allows the rails to provide sealing while the separated zone prevents heat conduction paths from reaching high-stress aperture areas, reducing thermal stress.
3Force
If fasteners are used to secure tiles to the annular outer wall, then mechanical attachment is improved, but heat conduction through fasteners increases stress in the annular outer wall
Solution Approach 1:
The patent extracts fasteners and rails from a circumferential region of the annular outer wall to create a fastener-free zone. This removal eliminates heat conduction paths through fasteners to the wall, reducing thermal stress while mechanical attachment is maintained in non-critical areas through alternative means.
4Area of stationary object
If multiple rows of tiles are used to form the annular inner wall, then coverage and cooling are improved, but discontinuities in the inner surface increase and affect coolant film continuity
Solution Approach 1:
The patent applies preliminary action by positioning lips at the downstream ends of tiles to extend axially toward upstream ends of adjacent tiles before the coolant flow reaches them. This pre-positioning creates a continuous surface that guides coolant flow smoothly across tile boundaries, maintaining film continuity despite the presence of multiple tile rows.
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 configuration enhances the mechanical integrity of the annular outer wall by reducing stress and preventing crack propagation, while preserving cooling effectiveness and extending the working life of the combustion chamber.
Implementation Method 1
The annular outer wall has one or more rows of apertures to direct coolant onto the outer surfaces of the lips at the downstream ends of the tiles
Implementation Method 2
the rails at the downstream ends of the tiles which are positioned close to the row of rows of apertures in the annular outer wall because the rails conduct heat from the tiles to the annular outer wall
Implementation Method 3
the annular inner wall has a plurality of effusion apertures to supply coolant from the chamber over an inner surface of the annular inner wall to provide a film of coolant on the inner surface
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A combustion chamber arrangement (15) comprises an annular outer wall (50) and an annular inner wall (52) comprising at least one row of tiles (52A). Each tile in the row of tiles (52A) has a rail (53) extending towards and sealing with the outer wall (50) and a lip (63) extending in a downstream direction from the row of tiles (52A). The outer wall (50) has a row of apertures (57) to direct coolant onto the lips (63) of the row of tiles (52A). Each tile (52A) has a fastener (72) positioned upstream of the rail (53) and the fastener (72) extends through a corresponding mounting aperture (70) to secure the tile (52A) to the outer wall (50). The rail (53) of each tile (52A) defines a plurality of slots (86) with the outer wall (50) and the slots (86) are arranged in a region (84) downstream of the corresponding fastener (72). None of the apertures (57) in the row of apertures (57) are arranged in a region (90) downstream of the fastener (72) of the tiles (52A). The arrangement reduces crack generation and propagation in the outer wall (50).