Carbon Seal Buffer Air and Oil Drain Paths in Turbine Struts
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Solution Overview
Problem
Gas turbine engines face challenges in preventing oil contamination of bleed air used for buffering carbon seals, which can lead to contamination of the gaspath and inefficient oil drainage systems.
Innovation Solution
A turbine engine design featuring a carbon seal system with a buffer air supply path and an oil drain path, utilizing struts and plenums to separate and manage air and oil flows effectively, reducing oil contamination and improving drainage efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bleed air is introduced through the adjacent engine shaft for buffering seals, then seal buffering is achieved, but oil contamination of the gaspath occurs
Solution Approach 1:
The system divides the buffer air supply and oil drainage functions into separate pathways. Buffer air is supplied through struts via a buffer air supply path, while oil is drained through dedicated oil drain paths in the same struts, preventing oil contamination of the buffer air and gaspath
Solution Approach 2:
The struts serve as intermediary structures that facilitate both buffer air supply and oil drainage functions. The struts contain internal passages that guide buffer air to the seal area and simultaneously provide separate passages for oil drainage, acting as a mediator between the bearing compartment and external systems
2Loss of substance
If oil is collected via scupper system at aft end of low pressure turbine, then oil drainage is achieved, but system complexity increases
Solution Approach 1:
The struts are designed to perform multiple functions: they provide structural support, serve as buffer air supply passages, and act as oil drainage pathways. This multi-functionality eliminates the need for separate scupper systems, reducing overall system complexity while maintaining effective oil drainage
Solution Approach 2:
The buffer air supply system and oil drainage system are merged into the strut structure. Both functions share the same structural component (struts) but use separate internal passages, consolidating multiple systems into a single integrated structure
3Object-affected harmful factors
If buffer air supply and oil drainage use separate paths, then oil contamination is reduced, but device complexity increases
Solution Approach 1:
The oil drainage passages are nested within the strut structure that also contains buffer air supply passages. Both flow paths are contained within the same structural component with separate internal channels, achieving functional separation while maintaining structural integration
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 effectively reduces oil contamination of the gaspath and minimizes oil accumulation, enhancing the operational efficiency and reliability of the turbine engine by consolidating buffer supply and weepage drain into a single stage of struts, while maintaining axial compactness.
Implementation Method 1
A buffer air supply path internally through one or more first struts of the stage of struts passes through a third plenum, a plurality of third holes, the second plenum, the plurality of second holes, the shaft plenum, and the plurality of first holes, to the first plenum
Implementation Method 2
A carbon seal system seals the bearing compartment and has: a carbon seal mounted to the case and a seal runner on the spool
Implementation Method 3
An oil drain path passes internally through one or more second struts of the stage of struts from the first plenum via one or more fourth holes
Data Source
AI summary
A turbine engine strut stage extends through a gaspath upstream of a guide vane stage. A carbon seal system seals a bearing compartment and has: a carbon seal mounted to the case and a seal runner on the spool; and a seal carrier carrying the carbon seal. The engine passes buffer air along a buffer air supply path internally through one or more first struts of the stage of struts. The engine drains oil along an oil drain path internally through one or more second struts of the stage of struts.