Turbomachine Combustion Chamber Injector Bellows Thermal Expansion
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Solution Overview
Problem
Existing regenerative cycle turbines face issues with thermal expansion mismatches between the combustion chamber and fuel injectors, leading to potential leaks and structural deformities due to hyperstatic assembly conditions, particularly when the injector passes through multiple walls with differing radial and longitudinal expansions.
Innovation Solution
The combustion chamber design incorporates a coaxial double envelope structure with a cylindrical bellows connection for the injector, allowing for axial, radial, and rotational freedom, ensuring a sealed and flexible interface between the injector and the walls to accommodate thermal expansions while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the injector passes through multiple walls with sealed connections, then the assembly provides structural support and sealing, but the hyperstatic assembly prevents absorption of thermal expansions leading to leaks and deformations
Solution Approach 1:
The patent employs flexible bellows connections at the injector-wall interfaces. These bellows are designed to expand and contract axially and radially, accommodating the differential thermal expansions between the injector and the combustion chamber walls while maintaining sealed connections. The flexibility of the bellows allows the system to adapt to thermal deformations without compromising the seal integrity.
Solution Approach 2:
The patent transitions from rigid fixed connections to dynamic flexible connections. The bellows components introduce degrees of freedom that allow the injector assembly to move and deform dynamically in response to thermal conditions. This dynamic capability enables the system to absorb thermal expansions and contractions while maintaining sealed interfaces, resolving the contradiction between sealing reliability and thermal adaptability.
2Stability of the object's composition
If the injector is rigidly fixed through multiple walls, then the assembly structure is stable, but the radial and longitudinal thermal expansions cause tightening of hole edges leading to deformations and fatigue
Solution Approach 1:
The flexible bellows connections replace rigid fixed mounts, allowing the injector assembly to accommodate thermal expansions without transmitting excessive stresses to the combustion chamber walls. The bellows absorb the thermal deformations through their own elastic deformation, preventing the tightening of hole edges that would otherwise lead to wall deformations and fatigue.
Solution Approach 2:
The patent changes the mechanical parameters of the connection system from rigid to flexible. By introducing compliant elements (bellows) with appropriate stiffness characteristics, the system can undergo controlled deformations that match the thermal expansion patterns, thereby protecting the structural integrity of the combustion chamber walls while maintaining assembly stability.
3Device complexity
If single holes are used for injector passage through walls, then the structure is simple, but radial expansion mismatch causes either leaks or tightening of hole edges
Solution Approach 1:
The patent introduces flexible bellows seals within the hole passages to accommodate radial expansion mismatches. These bellows maintain sealed connections even when the injector and wall expand at different rates, preventing both leaks and the tightening effects that would compromise structural integrity. This solution adds minimal complexity while significantly improving reliability.
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 thermal efficiency and prevents leaks by accommodating thermal expansions, reducing the risk of deformation and fatigue, thereby improving the overall performance and reliability of the turbine.
Implementation Method 1
the longitudinal thermal expansions of the injector, nor the radial and longitudinal thermal expansions of the metal walls subjected to highly differentiated temperatures
Implementation Method 2
a cylindrical bellows connection for the injector, allowing for axial, radial, and rotational freedom
Data Source
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AI summary
The invention discloses a turbomachine combustion chamber, comprising two coaxial walls (30, 31) of revolution extending one inside the other and delimiting between one another an annular air-circulation space (33), and an exterior wall (32), and at least one injector (35) passing through said walls (30 to 32) via apertures, characterized in that the injector comprises a peripheral tube connected to said walls (30 to 32) by three connections, at least two connections being of the slideway and/or ball-joint or bellows type.