Gas Turbine Insert Assembly Sealing and Thermal Expansion
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Solution Overview
Problem
The existing insert assemblies in gas turbines do not adequately secure sealing performance, leading to potential leaks and reduced thermal efficiency due to thermal elongation differences between the insert and airfoil components.
Innovation Solution
An insert assembly is designed with a cylindrical insert, a reinforcing member, and a retaining member, where the reinforcing member enhances the rigidity of the insert and the retaining member forms a sliding sealing interface, allowing for orthogonal positioning and absorption of thermal elongation, thereby preventing gaps and leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the insert is left free to absorb thermal elongation, then the insert can accommodate thermal expansion differences, but the sealing performance deteriorates due to gap formation at the free end
Solution Approach 1:
The patent employs a flexible sealing ring (O-ring) at the free end of the insert to maintain sealing contact despite thermal expansion differences. The elastomeric material of the sealing ring allows it to deform and maintain contact with the retaining member, preventing gap formation while accommodating the insert's thermal movement.
Solution Approach 2:
The retaining member acts as an intermediary between the insert and the airfoil body, providing a fixed reference point for sealing while allowing the insert to move freely for thermal expansion. The sealing ring mediates between the fixed retaining member and the moving insert end, ensuring continuous sealing contact.
2Reliability
If the insert is fixed rigidly to prevent leakage, then sealing performance improves, but the insert cannot absorb thermal elongation differences
Solution Approach 1:
The insert assembly is segmented into a fixed end (attached to airfoil body) and a free end (with sealing ring), allowing different portions to serve different functions. The fixed end provides sealing stability while the free end accommodates thermal expansion, resolving the contradiction through functional segmentation.
3Reliability
If the insert is made more rigid to prevent deformation, then sealing stability improves, but manufacturing complexity increases
Solution Approach 1:
The sealing function is extracted from the insert body and placed in a separate retaining member with a sealing ring. This allows the insert to remain simple and flexible for thermal expansion while the sealing function is handled by a dedicated component, reducing overall manufacturing complexity.
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 stabilizes the sealing performance, reduces air leakage, and maintains thermal efficiency by enhancing the insert's rigidity and accommodating thermal expansion, ensuring reliable cooling performance.
Implementation Method 1
The retaining member comes in contact with an end of the insert so as to form a sealing interface on which the insert is slidable in the radial direction
Implementation Method 2
The reinforcing member has a plate shape and is provided inside the insert. The reinforcing member extends in a direction orthogonal to the radial direction, and is fixed at both ends to an inner circumferential surface of the cylindrical body
Implementation Method 3
This type of cylindrical body undergoes thermal elongation differently from the airfoil body. In such a case, therefore, a first end of two ends of the cylindrical body is fixed to the airfoil body by seal welding or brazing, while a second end is left free relative to elongation of the cylindrical body in a longitudinal direction
Data Source
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AI summary
An insert assembly (79) includes an insert (80), a reinforcing member (85), and a retaining member (90). The insert (80) is fixed to an end of an airfoil body (51) on one side in a radial direction. The reinforcing member (85) is disposed adjacent to an end of the insert (80) on the other side in the radial direction and enhances the rigidity of the insert (80). The retaining member (90) is fixed to an end of the airfoil body (51) on the other side in the radial direction, and allows the insert (80) to be positioned relative to the airfoil body (51) in a direction orthogonal to the radial direction.