Face Seal Feed-Slot Structure for Lower Contact Pressure
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Solution Overview
Problem
Existing face seal arrangements in gas turbine engines experience high contact pressure and net closing force, leading to high heat generation, increased engine friction losses, and reduced service life due to high heat generation and friction.
Innovation Solution
A face seal arrangement with a sealing ring design featuring circumferentially spaced feed slots and annular grooves that utilize high-pressure fluid to counteract the biasing forces, reducing contact pressure and net closing force while maintaining an effective seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high contact pressure and high net closing force are applied to the face seal, then sealing effectiveness is improved, but heat generation increases and service life is reduced
Solution Approach 1:
The patent introduces pressurized fluid (pneumatic/hydraulic means) to act on the face seal through feed slots and annular grooves, creating a counter-force that reduces contact pressure between the seal faces. This allows effective sealing with reduced mechanical contact pressure, thereby reducing heat generation and improving service life
Solution Approach 2:
The patent changes the pressure parameter of the fluid acting on the seal face. By controlling the fluid pressure to match or exceed the spring bias force, the net closing force is reduced, which directly reduces contact pressure and the resulting heat generation while maintaining sealing effectiveness
2Reliability
If high contact pressure is applied to the face seal, then sealing effectiveness is improved, but friction losses increase
Solution Approach 1:
The patent uses pressurized fluid delivered through feed slots and annular grooves to create a counter-force that reduces the normal contact pressure between seal faces. Since friction force is proportional to normal contact pressure, reducing the latter directly reduces friction losses and energy waste
3Reliability
If high net closing force is applied to the face seal, then sealing effectiveness is improved, but service life is reduced due to heat generation
Solution Approach 1:
The patent employs pressurized fluid delivered through the feed slots and annular grooves to counteract the spring bias force, reducing the net closing force on the seal face. This reduction in net closing force decreases heat generation and thermal stress, thereby extending the service life of the face seal
Solution Approach 2:
The patent changes the pressure parameter of the fluid to dynamically balance or counteract the spring force, reducing the net closing force. This parameter change directly reduces the thermal load on the seal, extending its operational life while maintaining sealing effectiveness
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 design reduces heat generation and friction losses, thereby extending the service life of the face seal and improving engine efficiency.
Implementation Method 1
High pressure fluid is delivered through a plurality of circumferentially spaced feed slots to an annular groove on the sealing face to provide a counter-force
Implementation Method 2
The design reduces heat generation and friction losses, thereby extending the service life of the face seal and improving engine efficiency
Data Source
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AI summary
A bearing is mounted to a static structure outwardly of the shaft, and supporting the shaft. A bearing compartment (222) is defined by face seal arrangements (200) on each of two axial sides of a bearing. Each face seal arrangement (200) includes a seal seat (228) rotating with the shaft and a non-rotating sealing ring (202). The seal housing (206) is exposed to high pressure air outward of the bearing compartment (222). A coil spring (210) biases the seal housing (206) towards the seal seat (228), such that the sealing face (212) is biased into contact with the seal seat (228) by a bias force including a net fluid force acting on the seal housing (206) and the coil spring (210). The sealing face (212) is defined by a contact portion (214) contacting the seal seat (228) and a feed portion (213) recessed from the seal seat (228). The feed portion (213) includes a plurality of circumferentially spaced feed slots (216) fluidly connected to at least one annular groove (218).