Mid-Turbine Frame Plenum Cooling Architecture
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Solution Overview
Problem
Current mid-turbine frame assemblies in gas turbine engines face challenges in effectively cooling high-temperature components, such as the inter-turbine duct and hollow struts, which are subjected to high thermal stresses, leading to inefficiencies in load transfer and potential thermal stress issues.
Innovation Solution
A mid-turbine frame assembly with a main plenum system that circulates cooling air from the compressor to a rotor cavity, a secondary plenum for pressurizing seals, and a containment ring plenum, ensuring efficient cooling and load transfer while minimizing thermal stress through strategically designed structural components and seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is introduced around the inter-turbine duct and into the hollow struts to cool them, then the temperature of the inter-turbine duct and hollow struts is reduced, but the device complexity increases due to the need for multiple plenums and cooling air distribution systems
Solution Approach 1:
The cooling system is segmented into multiple functional plenums (main plenum, secondary plenum, containment ring plenum) that are spatially distributed and functionally specialized. Each plenum serves a specific cooling zone, allowing independent temperature control and cooling air distribution to different components (inter-turbine duct, hollow struts, containment ring) without requiring a single complex distribution system.
Solution Approach 2:
The plenums are nested within each other hierarchically: the containment ring plenum is nested within the secondary plenum, which is nested within the main plenum. This nested structure allows cooling air to be distributed from the outer main plenum to inner plenums, creating a compact multi-level cooling system that reduces overall complexity while providing targeted cooling to multiple components.
2Strength
If a mid-turbine frame assembly is used to support bearings and transfer loads, then the structural strength and load transfer capability are improved, but the weight of the stationary structure increases
Solution Approach 1:
The mid-turbine frame assembly is designed as a multi-functional structure that simultaneously performs bearing support, load transfer, and cooling air distribution functions. The frame structure integrates structural support elements with cooling plenums, allowing the same components to serve both mechanical support and thermal management functions, thereby reducing the need for separate dedicated structures and minimizing overall weight.
Solution Approach 2:
The cooling system components (plenums, cooling air passages) are merged with the structural frame elements rather than being separate additions. The main plenum, secondary plenum, and containment ring plenum are integrated into the frame structure, allowing cooling functionality to be embedded within the load-bearing structure, thus avoiding additional weight from separate cooling system components.
3Reliability
If multiple plenums are used to distribute cooling air to different components, then the cooling efficiency and temperature control are improved, but the manufacturing complexity increases
Solution Approach 1:
The cooling air distribution paths and plenum structures are pre-configured and integrated into the mid-turbine frame assembly during manufacturing. The main plenum, secondary plenum, and containment ring plenum are designed as pre-assembled units with built-in cooling air passages, allowing cooling functionality to be established before final installation. This preliminary configuration simplifies on-site assembly and reduces manufacturing complexity despite the multi-plenum design.
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 provides enhanced cooling efficiency for high-pressure and low-pressure turbine components, reduces thermal stress, and maintains the containment ring within a safe temperature range, ensuring reliable engine operation and efficient load transfer.
Implementation Method 1
cooling air is introduced around the inter-turbine duct and into the hollow struts to cool the same
Implementation Method 2
circulating the cooling air from the main plenum to a secondary plenum for pressurizing first seals located between the outer case and the outer wall and second seals located between the inner case and the inner wall
Data Source
AI summary
A mid-turbine frame (MTF) assembly having: an outer case circumferentially extending around a central axis; an outer ring secured to the outer case and disposed radially inwardly of the outer case relative to the central axis; an inner case structurally connected to the outer case and disposed radially inwardly of the outer ring relative to the central axis; a main plenum circumferentially extending around the central axis and located between the outer case and the outer ring, the main plenum having an inlet fluidly connectable to a source of cooling air, a first outlet fluidly connected to a secondary plenum between the main plenum and the inner case, a second outlet configured to be fluidly connected to a rotor cavity of the low-pressure turbine, and a third outlet configured to be fluidly connected to a plenum surrounding a containment ring of the low-pressure turbine.