Face Seal Balance Ratio Tuning to Cut Heat and Oil Coking
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Solution Overview
Problem
Existing face seal arrangements in gas turbine engines experience high axial closing forces, leading to excessive heat generation, oil coking, and reduced service life due to a high balance ratio and spring force.
Innovation Solution
A face seal arrangement with a reduced balance ratio between 0.52 and 0.58, featuring a seal housing made of titanium alloy or ceramic, and a seal seat design with radially outermost surfaces and oil management grooves to optimize oil distribution and reduce heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high balance ratio and high spring force are used to ensure sealing contact, then sealing reliability is improved, but axial closing force increases leading to high heat generation and reduced service life
Solution Approach 1:
The patent changes the balance ratio parameter from high (prior art) to reduced (0.52-0.58), and adjusts spring force parameters to optimized ranges. This parameter optimization reduces axial closing force while maintaining sealing reliability, directly resolving the contradiction between sealing reliability and heat generation
Solution Approach 2:
The seal seat design incorporates radially outermost surfaces and localized oil management grooves that concentrate lubrication and heat dissipation at critical contact zones. This local quality enhancement allows reduced overall axial force while maintaining sealing performance at the sealing interface
2Reliability
If high axial closing force is applied to maintain seal contact, then sealing effectiveness is improved, but oil coking occurs and service life is reduced
Solution Approach 1:
By optimizing the balance ratio to 0.52-0.58 and adjusting spring force parameters, the patent reduces axial closing force to levels that prevent oil coking while maintaining adequate sealing contact, thereby extending service life without sacrificing sealing effectiveness
Solution Approach 2:
The oil management grooves and radially outermost surfaces act as intermediaries that distribute lubricating oil more effectively at the sealing interface. This improved lubrication reduces friction and heat generation, preventing oil coking and extending service 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 reduced balance ratio and optimized seal seat design lower axial closing forces and heat generation, mitigating oil coke formation, reducing seal wear, and improving reliability.
Implementation Method 1
the seal seat has an inner diameter and an outer diameter. There is a plurality of slots circumferentially spaced and have an inlet to receive oil from an inner diameter of the seal seat and a circumferentially spaced outlet to outlet oil to an outer diameter of the seal seat
Data Source
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AI summary
A face seal arrangement (150) includes a seal seat (162) rotating with a shaft and a nonrotating face seal including a sealing ring (154). The sealing ring (154) includes a sealing face (158) biased into contact with the seal seat (162). The sealing ring (154) also has a groove (160) defined remote from the seal face relative to the seal seat (162). The groove (160) provides a pressure face that will be exposed to high pressure air outward of the bearing compartment (107). A coil spring (153) biases the seal housing (152) towards the seal seat (162), such that the sealing face (158) of the sealing ring (154) is biased into contact with seal seat (162) by air pressure against the pressure face, and the coil spring (153). A balance ratio is defined between an area of the pressure face and an area of the sealing face (158), the balance ratio is between 0.5 and 0.64.