Mid-Turbine Frame Hollow Spokes for Cooling and Load Transfer
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Solution Overview
Problem
Current mid-turbine frames in gas turbine engines lack effective cooling methods to manage bearing loads and transfer air efficiently between high and low-pressure turbine stages, leading to potential thermal and mechanical issues.
Innovation Solution
The design incorporates a mid-turbine frame with branching passages and tubes that distribute cooling airflow through a distribution tube and pass-thru tube system, providing fluid communication and piston seals to efficiently cool the components, including the use of hollow spokes for structural support and airflow distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mid-turbine frame is used to support bearings and transfer loads, then structural support and load transfer are improved, but thermal management becomes insufficient leading to overheating risks
Solution Approach 1:
The mid-turbine frame is divided into multiple hollow spokes instead of a solid structure. Each spoke acts as an independent cooling passage, allowing cooling air to flow through them and remove heat from bearing supports and other hot components. This segmentation enables the structure to simultaneously maintain strength while providing effective thermal management.
Solution Approach 2:
Cooling air is introduced as an intermediary medium to transfer heat away from critical components. The hollow spokes serve as conduits for this cooling air, which absorbs heat from the bearing supports and other hot areas, then exits through the turbine stages. This intermediary cooling air flow resolves the thermal management issue while preserving structural integrity.
2Productivity
If air is routed from high pressure turbine stage to low pressure turbine stage, then airflow transfer is improved, but cooling efficiency is insufficient without dedicated cooling passages
Solution Approach 1:
The hollow spokes of the mid-turbine frame serve multiple functions simultaneously: they provide structural support as load-bearing elements, act as cooling passages for thermal management, and serve as airflow routes from the high pressure turbine stage to the low pressure turbine stage. This multi-functionality resolves the contradiction by making the same structure responsible for both efficient airflow transfer and effective cooling.
Solution Approach 2:
The structural support function and cooling airflow passage function are merged into a single integrated hollow spoke structure. Rather than having separate support elements and separate cooling ducts, the design combines these functions into the same component, allowing the mid-turbine frame to efficiently transfer both mechanical loads and cooling airflow simultaneously.
3Reliability
If branching passages are added to distribute cooling air, then cooling coverage is improved, but device complexity increases
Solution Approach 1:
The cooling air distribution system is segmented into multiple independent hollow spokes instead of using a complex network of separate ducts and passages. Each spoke is a simple hollow cylinder that receives cooling air and distributes it to specific areas. This segmentation simplifies the overall design while achieving comprehensive cooling coverage across all critical components.
Solution Approach 2:
The same hollow spoke structure that provides structural support also serves as the cooling air distribution network. By making the structural elements themselves the cooling passages, the design eliminates the need for separate, complex cooling ductwork. This multi-functionality achieves extensive cooling coverage while maintaining relatively simple device architecture.
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
This configuration enhances cooling efficiency, maintains structural integrity, and optimizes power transfer by directing airflow to critical areas within the engine, thereby improving the overall performance and reliability of the gas turbine engine.
Implementation Method 1
A mid-turbine frame (MTF) is positioned between a high pressure turbine stage and a low pressure turbine stage of a gas turbine engine. The MTF supports one or more bearings and transfers bearing loads from an inner portion of the gas turbine engine to an outer engine frame.
Implementation Method 2
The MTF also serves to route air from the high pressure turbine stage to the low pressure turbine stage.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A mid-turbine frame (57) for a gas turbine engine (20) includes at least one spoke (65) for connecting an outer frame case (62) to an inner frame case (64). At least one spoke (65) includes an inlet passage (118) and at least two branches (120, 122) that extend transverse to the inlet passage (118).