Boltless Gas Turbine Interstage Seal Design
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Solution Overview
Problem
Existing gas turbine interstage seal designs face issues with high temperature exposure, risk of screw connection failure, material limitations due to thermal expansion, increased air resistance, and leakage due to asymmetrical thermal expansion and complex assembly processes.
Innovation Solution
A boltless interstage seal design featuring a radial outer ring supported by guide vanes and a radial inner ring with radial tongue and groove connections, secured by holding elements that prevent axial slipping and deformation, allowing for separate material optimization and reduced leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If screw connections are used to assemble interstage seal rings, then the sealing function is achieved, but the screw connection is exposed to high temperatures and may fail, damaging rotor disks
Solution Approach 1:
The patent removes the screw connection from the high-temperature environment by using a boltless design where the interstage seal rings are pressed together axially. The holding elements are extracted from the thermal zone, eliminating the risk of thermal failure while maintaining the sealing function through alternative mechanical means.
Solution Approach 2:
The patent introduces an intermediary pressing force mechanism that transmits axial compression through the seal rings without requiring direct screw-threaded connections in the hot zone. This intermediary force transmission method allows sealing to be achieved while keeping fastening elements away from the high-temperature environment.
2Reliability
If screw connections are used to assemble interstage seal rings, then the sealing function is achieved, but other components can be damaged during assembly, for example fir tree tooting on the pane
Solution Approach 1:
The patent extracts the invasive screw connection from the assembly process, replacing it with a non-invasive pressing mechanism. This eliminates the risk of screw heads damaging sensitive components like fir tree tooting on the pane while still achieving the necessary sealing function.
3Reliability
If screw connections are used to assemble interstage seal rings, then the sealing function is achieved, but turbulence is created in the air flows between rotor and stator, increasing air resistance
Solution Approach 1:
The patent removes the screw connection that disrupts airflow, replacing it with a pressing mechanism that maintains seal integrity without creating turbulence. This extraction of the intrusive fastening element eliminates the associated air resistance and energy loss.
4Reliability
If screw connections are used to assemble interstage seal rings, then the sealing function is achieved, but the choice of material is limited due to thermal expansion differences
Solution Approach 1:
The patent extracts the constraint imposed by screw connections, allowing independent material selection for each seal ring based on optimal thermal expansion characteristics. The pressing mechanism eliminates the need to match thermal expansion rates between connected components, greatly enhancing material versatility.
5Reliability
If two separate interstage sealing rings are used, then the sealing function is achieved, but the system becomes statically indeterminate with constraining forces between rings
Solution Approach 1:
The patent transforms the static, indeterminate ring arrangement into a dynamic system where axial pressing forces can be adjusted. This allows the rings to move independently to accommodate thermal expansion while maintaining sealing contact, eliminating constraining forces and improving stability.
6Ease of manufacture
If split intermediate sealing rings are used, then assembly is simplified, but complex milling work is required and components cannot be exchanged individually
Solution Approach 1:
The patent segments the interstage seal into multiple independent rings that can be manufactured separately with standard processing, then assembled by pressing. This segmentation avoids complex milling work while maintaining the ability to exchange individual components, balancing manufacturing simplicity with component versatility.
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
The solution eliminates screw connection failures, reduces flow losses, allows for independent material selection for optimal thermal performance, and simplifies assembly, resulting in a cost-effective and structurally robust interstage seal arrangement.
Implementation Method 1
the relative radial displacement due to different thermal expansions must be reduced to a minimum in order to prevent the flange from slipping
Implementation Method 2
the holding elements themselves are preferably secured against falling out by the strips of the guide vanes
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to an intermediate-stage sealing arrangement of a gas turbine with a radially outer ring 1, which is supported in guide vanes, and with a radially inner ring 3, which is supported directly on the outer ring 1, wherein the inner ring 3 is axially positioned in one axial direction by an annular projection 10 of the outer ring 1 which simultaneously serves as a seal and is held in the other axial direction relative to the outer ring 1 by means of several removable retaining elements 7, 8, 9, 22 penetrating the outer ring 1.