Annular Combustion Chamber Bottom Assembly with Sliding Flanges
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Solution Overview
Problem
The assembly of annular combustion chambers with axial walls and bottoms made of materials having different coefficients of thermal expansion poses challenges in mechanical strength and vibration damping, as conventional bolting systems fail to provide sufficient free expansion and effective vibration damping.
Innovation Solution
An assembly system featuring external and internal axial walls connected by a chamber bottom with internal and external hooking flanges, each with a sliding sleeve and radial clearance, allowing free radial expansion and incorporating metallic washers for reduced wear and prestressed flanges for dynamic stability, along with optional damping means like spiral or blade springs and sealing lamella-type circular seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bolting systems are used to fix the chamber bottom to the axial walls, then the assembly provides mechanical strength, but it restricts free thermal expansion of the bottom relative to the walls
Solution Approach 1:
The attachment flanges are designed to transition from a fixed rigid connection during assembly to a dynamic sliding connection during operation. The flanges slide along guide surfaces perpendicular to the expansion direction, allowing the bottom to expand freely while maintaining mechanical connection. This dynamic adaptation resolves the contradiction between maintaining strength and allowing thermal expansion.
Solution Approach 2:
The system changes the constraint parameters from fully fixed (conventional bolting) to partially constrained with controlled sliding freedom. The guide surfaces define specific degrees of freedom that allow expansion while preventing movement in other directions, thus maintaining structural integrity. This parameter change enables both strength and thermal expansion compatibility.
2Stability of the object's composition
If rigid attachment flanges are used to ensure structural stability, then mechanical strength is maintained, but vibration damping is insufficient
Solution Approach 1:
The attachment flanges are designed with flexible characteristics that allow them to deform and absorb vibrations while maintaining structural connection. The flanges can flex perpendicular to the expansion direction, providing inherent vibration damping while preserving structural stability through their constrained sliding motion.
Solution Approach 2:
The guide surfaces act as intermediaries between the rigid bottom structure and the axial walls. They mediate the interaction by allowing controlled sliding motion that dampens vibrations while maintaining the mechanical connection, thus resolving the contradiction between stability and vibration damping.
3Adaptability or versatility
If the bottom is allowed to expand freely relative to the axial walls, then thermal expansion is accommodated, but bending stresses increase on the attachment flanges
Solution Approach 1:
The attachment system is segmented into multiple independent flanges distributed around the perimeter of the bottom. Each flange handles a portion of the expansion load independently, distributing the bending stresses across multiple locations rather than concentrating them at single attachment points. This segmentation reduces the stress on each individual flange while allowing free expansion.
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 enables effective damping of vibrations and reduces bending stresses on attachment flanges, maintaining mechanical integrity and reducing wear, while allowing for free expansion of the chamber bottom relative to the axial walls, thus enhancing the durability and operational stability of the combustion chamber.
Implementation Method 1
a determined radial clearance being provided between the nut and one of the attachment flanges so as to allow a free radial expansion of the chamber bottom relative to the axial walls
Implementation Method 2
The presence of flexible but pre-stressed attachment flanges combined with fastening systems having a determined radial play provided between the nut and the axial wall has the effect of improving both the damping of the vibrations undergone by the combustion chamber
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Annular combustion chamber (10) comprising axial walls (28) connected by a chamber bottom (30) having a coefficient of thermal expansion different from that of the axial walls, the chamber bottom being provided with a plurality of internal and external mounting flanges (34) fixed by fastening systems (36) to end portions of the axial walls. Each fastening system consists of a screw (40), a nut (46) tightened at one end of the screw, and a sliding sleeve (48) disposed around the screw between the nut and the corresponding end portion of the axial wall, a determined radial clearance (J) being provided between the nut and the end portion of the axial wall so as to allow, during operation, free radial expansion of the chamber bottom (30) relative to the axial walls.