Split Helical Piston Seal Using Carbon-Carbon to Reduce Rotor Wear
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Solution Overview
Problem
Existing gas turbine engine sealing technologies face challenges in reducing wear on rotors due to shifting seals during engine cycles, despite the seals and rotors rotating in the same direction with minimal relative movement, and traditional metallic seals cause higher centrifugal forces and wear.
Innovation Solution
A split seal with a helical shape and carbon-carbon composite material is used, featuring mateable end sections that expand to fit over a shaft's annular seal channel, reducing wear by being low in weight and density, and highly lubricious, allowing for effective sealing without catching on the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metallic seals are used, then sealing effectiveness is maintained, but centrifugal forces and wear on the rotor increase
Solution Approach 1:
The seal is constructed from carbon-carbon composite material consisting of carbon fibers embedded in a graphite matrix. This composite structure provides both the sealing effectiveness needed for reliability and reduced density to minimize centrifugal forces, directly resolving the contradiction between maintaining sealing performance and reducing harmful centrifugal effects on the rotor.
Solution Approach 2:
The invention changes the material parameters of the seal from traditional metallic materials to carbon-carbon composite materials. This parameter change results in lower density (reducing centrifugal forces) while maintaining or improving sealing effectiveness through the self-lubricating properties of the carbon-carbon composite, thereby resolving the contradiction between sealing reliability and reduced wear.
2Ease of manufacture
If a split seal design is used, then installation and replacement are simplified, but the seal structure becomes more complex
Solution Approach 1:
The seal is divided into two separate end sections that can be independently manufactured and then assembled together. This segmentation allows for simpler manufacturing of each individual section and facilitates easier installation and replacement of the seal assembly, directly addressing the ease of manufacture requirement while the modular nature actually simplifies the overall structural 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
The carbon-carbon composite split seal effectively reduces rotor wear by minimizing centrifugal forces and providing a low-friction, durable sealing solution that maintains contact with the rotor surface during engine operation.
Implementation Method 1
reduces wear by being low in weight and density, and highly lubricious, allowing for effective sealing without catching on the rotor
Implementation Method 2
highly lubricious, allowing for effective sealing without catching on the rotor
Data Source
Figure 1
Figure 2~3
Figure 4(a)~4(d)
AI summary
A gas turbine engine (20) includes a rotor (62) that has a sealing surface (68) and a shaft (70) that is rotatable about an engine central axis (A). The shaft (70) has an annular seal channel (72) that opens to the seal surface (68), and there is a split seal (74) that is insertable into the annular seal channel (72) for sealing against the seal surface (68). The split seal (74) includes first and second end sections (74a, 74b) that are mateable to each other. The split seal (74) has a helical shape when in a state of rest such that the first and second end sections (74a, 74b) are axially offset from each other.