Ceramic Cladding Axial Bracing in Combustion Chambers
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Solution Overview
Problem
The integration of fracture-sensitive ceramic monoliths into tubular combustion chambers is challenging due to exposure to strong combustion oscillations and vibrations, requiring a vibration-damping, permanent mounting solution that avoids critical tensile or shear stress, while also allowing for thermal expansion and managing axial and radial composite loads, position definition, and anti-twist protection.
Innovation Solution
A ceramic-lined tubular combustion chamber design featuring a conical metallic jacket with an intermediate layer, where the ceramic tube is axially braced and composed of heat shield segments with a tongue-and-groove connection, utilizing a resilient intermediate layer to transmit radial forces and ensure compressive prestresses, thereby preventing tensile stresses and allowing thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic monoliths are integrated into the metal combustion chamber, then temperature resistance is improved, but the component becomes sensitive to vibrations and combustion oscillations
Solution Approach 1:
The patent employs a composite structure combining ceramic heat shield segments with a metal jacket and resilient intermediate layer. This composite design allows the ceramic to provide temperature resistance while the metal and resilient materials absorb vibrations and combustion oscillations, resolving the contradiction between temperature resistance and vibration sensitivity
Solution Approach 2:
The resilient intermediate layer is specifically designed to cushion and dampen vibrations and combustion oscillations before they can affect the ceramic segments. This beforehand cushioning protects the fracture-sensitive ceramic from vibrational damage while maintaining thermal protection capabilities
2Stability of the object's composition
If the ceramic tube is axially braced to provide stability, then position stability is improved, but tensile stresses may develop in the ceramic
Solution Approach 1:
The resilient intermediate layer acts as an intermediary between the axially braced ceramic segments and the metal jacket. It transmits compressive forces while accommodating thermal expansion and preventing tensile stress development, thus maintaining position stability without inducing harmful tensile stresses
Solution Approach 2:
The design explicitly accounts for thermal expansion by allowing the ceramic segments to expand freely within the resilient intermediate layer. This prevents the development of tensile stresses during thermal cycles while maintaining axial bracing for position stability
3Reliability
If the ceramic segments are tightly fitted to eliminate gaps, then seal quality is improved, but thermal expansion is impeded
Solution Approach 1:
The gap geometry is designed to be dynamic rather than static - it allows for thermal expansion during operation while maintaining adequate seal quality. The resilient intermediate layer and specific gap configuration enable the structure to adapt to thermal conditions, closing gaps sufficiently for sealing while accommodating expansion movements
4Strength
If the interface geometry is designed to transmit loads, then load-bearing capacity is improved, but tensile stresses may occur in the interface area
Solution Approach 1:
The resilient intermediate layer converts potentially harmful tensile stresses into compressive pre-stresses in the ceramic segments. This design transformation ensures that the interface geometry can transmit loads effectively while the resilient material prevents tensile stress concentration by maintaining compressive contact pressure
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 design enhances the load-bearing capacity of the ceramic lining, increases temperature resistance, reduces cooling air consumption, and extends service life, while minimizing costs and maintaining a gap-free structure.
Implementation Method 1
the axial bracing of the heat shield segments in the conical direction generates radial forces which are transmitted via the resilient elements to be transferred to the outer surface of the ceramic
Implementation Method 2
Differences in thermal expansion occur in particular between the hot and cold sides of the ceramic segments
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a combustion chamber (1) comprising a jacket (3) that is arranged around a principal axis (2) of the combustion chamber (1), and a ceramic tube (4) that is arranged inside the jacket (3), wherein an intermediate layer (5) is arranged between the jacket (3) and the ceramic tube (4), and the jacket (3) is at least partially conical, and the ceramic tube (4) is under axial stress in the jacket (3) along the principal axis (2), wherein the ceramic tube (4) is an assembly of multiple heat shield segments (10), wherein the heat shield segments (10) each have a hot side (11) that is designed to come into contact with a hot medium, a cold side (12) that is opposite the hot side (11) and is oriented toward the jacket (3), and a circumferential rim (13) between the hot side (11) and the cold side (12), and in the cold state individual heat shield segments (10) of a segment row (14) have, on the rim (13), bearing surfaces (15) that the adjoin the cold side (12) and gaps (16) that open toward the hot gas side (11).