Annular Combustion Chamber Assembly Segmentation
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Solution Overview
Problem
The existing annular combustion chamber assembly techniques in turbomachines face issues with manufacturing tolerances and stiffness accumulation, leading to mechanical strength reduction, air leaks, and vibration-induced damage due to excessive tightening requirements and potential slip between parts.
Innovation Solution
The proposed solution involves fixing the internal and external downstream ends of the annular fairing in axial alignment with the cylindrical walls' ends, using complementary indentations or undulations with bolts, which reduces stiffness and manufacturing tolerance accumulation, enhances radial flexibility, and optimizes tightening torque, while angularly offsetting bolts to improve rigidity and resist vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the upstream part of the combustion chamber is assembled by superposing the radially inner and outer downstream ends of the fairing on the radially inner and outer upstream ends of the cylindrical walls, then the assembly can be fixed by bolting or welding, but the accumulation of manufacturing tolerances and stiffnesses requires excessive tightening torque that reduces mechanical strength and causes plastic deformation
Solution Approach 1:
The invention divides the assembly into two separate radial superposition operations: first fixing the cylindrical walls to the bottom wall, then fixing the fairing to the bottom wall independently. This segmentation eliminates the need to superpose three parts simultaneously, reducing the accumulation of manufacturing tolerances and stiffnesses from three components to two separate two-component assemblies.
Solution Approach 2:
The invention changes the assembly sequence from a three-part radial superposition in one dimension to two independent two-part radial superpositions. By fixing the fairing and cylindrical walls separately to the bottom wall in axial alignment, the assembly operates in a different dimensional sequence, reducing the cumulative effect of tolerances and stiffnesses.
2Stability of the object's composition
If strong tightening torque is applied to compensate for stiffness and assembly clearances, then the parts can be fixed together, but this leads to plastic deformation of the fairing and cylindrical walls, reducing mechanical strength and life
Solution Approach 1:
The invention segments the fastening operation into two independent stages: first fastening the cylindrical walls to the bottom wall, then fastening the fairing to the bottom wall. This segmentation allows each fastening stage to accommodate tolerances and stiffness with appropriate torque, avoiding the excessive torque that would result from attempting to fasten all three parts simultaneously.
3Adaptability or versatility
If axial slots are produced in the ends of the fairing to obtain flexibility for good mechanical connection, then the parts can be connected, but these slots induce additional air flows that disturb the air flow and overall operation of the turbomachine
Solution Approach 1:
The invention segments the flexibility requirement from the air flow path. By providing flexibility through the independent fastening of the fairing to the bottom wall (rather than through slots), the solution accommodates manufacturing tolerances without creating openings in the air flow path, thus avoiding air flow disturbance.
4Ease of manufacture
If the ends of the fairing and cylindrical walls are radially superposed on the bottom edges of the chamber, then the parts can be assembled, but the accumulation of stiffnesses requires excessive tightening that can cause plastic deformation and reduce mechanical strength
Solution Approach 1:
The invention segments the radial superposition operation into two independent operations: first superposing and fastening the cylindrical walls radially to the bottom wall, then superposing and fastening the fairing radially to the bottom wall. This segmentation reduces the accumulation of stiffnesses from three simultaneously fastened parts to two separate two-part fastening operations, allowing appropriate tightening torque for each stage.
Data Source
Figure 1
Figure 2~4
AI summary
Annular combustion chamber of a turbomachine, comprising two radially internal and radially external cylindrical walls, fixed by bolting at their upstream ends (46, 48) on internal (54) and external (56) annular rims of an annular chamber bottom, and an annular fairing extending upstream from the chamber bottom and whose internal (50) and external (52) annular ends are fixed by bolting on the rims of the chamber bottom, in axial alignment with the annular ends (46, 48) of the chamber walls.