Mid-Turbine Frame Intermediary Plenum Cooling Air Routing
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Solution Overview
Problem
The effectiveness of secondary air cooling in aircraft engines, particularly in the mid-turbine frame assembly, is compromised by the sealing efficiency of seals, which can lead to reduced cooling of components like the low-pressure turbine plenum, affecting the overall performance and reliability of the engine.
Innovation Solution
A method and configuration that involves an intermediary plenum system to feed cooling air directly to the low-pressure turbine plenum, bypassing the main mid-turbine frame plenum, ensuring consistent cooling regardless of the sealing effectiveness of the sealing rings, and potentially reducing the need for external piping and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cooling air is delivered through the main mid-turbine frame plenum using sealing rings, then the cooling system is simple in structure, but the cooling effectiveness deteriorates when sealing efficiency decreases
Solution Approach 1:
The cooling air delivery system is segmented into two independent paths: (1) a first portion of cooling air is delivered to the low-pressure turbine plenum through the main mid-turbine frame plenum via sealing rings, and (2) a second portion of cooling air is delivered directly to the low-pressure turbine plenum through an intermediary plenum that bypasses the main plenum and sealing rings. This segmentation ensures that cooling effectiveness is maintained even if sealing efficiency deteriorates.
Solution Approach 2:
An intermediary plenum is introduced as a mediator between the secondary air source and the low-pressure turbine plenum. This intermediary plenum receives secondary air and delivers a portion of it directly to the low-pressure turbine plenum without passing through the main mid-turbine frame plenum and its sealing rings, thereby providing an alternative cooling path that is independent of sealing efficiency.
2Reliability
If an intermediary plenum system is used to bypass the main plenum, then cooling reliability is improved, but device complexity increases
Solution Approach 1:
The cooling air delivery system is segmented into two independent paths: (1) a first portion of cooling air is delivered to the low-pressure turbine plenum through the main mid-turbine frame plenum via sealing rings, and (2) a second portion of cooling air is delivered directly to the low-pressure turbine plenum through an intermediary plenum that bypasses the main plenum and sealing rings. This segmentation ensures that cooling effectiveness is maintained even if sealing efficiency deteriorates.
Solution Approach 2:
The intermediary plenum serves multiple functions: it receives secondary air, stores it temporarily, and delivers a portion of it directly to the low-pressure turbine plenum. This multi-functionality allows the system to maintain cooling reliability without requiring entirely separate cooling systems, thereby limiting the increase in device complexity.
3Ease of manufacture
If sealing rings are used to seal the main plenum, then manufacturing is simplified, but cooling performance deteriorates due to sealing inefficiency
Solution Approach 1:
An intermediary plenum is introduced as a mediator between the secondary air source and the low-pressure turbine plenum. This intermediary plenum receives secondary air and delivers a portion of it directly to the low-pressure turbine plenum without passing through the main mid-turbine frame plenum and its sealing rings, thereby providing an alternative cooling path that is independent of sealing efficiency.
Solution Approach 2:
The cooling air delivery system is segmented into two independent paths: (1) a first portion of cooling air is delivered to the low-pressure turbine plenum through the main mid-turbine frame plenum via sealing rings, and (2) a second portion of cooling air is delivered directly to the low-pressure turbine plenum through an intermediary plenum that bypasses the main plenum and sealing rings. This segmentation ensures that cooling effectiveness is maintained even if sealing efficiency deteriorates.
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 maintains proper cooling of the low-pressure turbine components even if the sealing efficiency of the mid-turbine frame plenum's sealing rings decreases, providing increased tolerance and weight savings by ensuring independent cooling air delivery to the low-pressure turbine plenum.
Implementation Method 1
an intermediary plenum system to feed cooling air directly to the low-pressure turbine plenum, bypassing the main mid-turbine frame plenum
Implementation Method 2
Secondary air is introduced around the inter-turbine duct and into hollow struts for cooling and other purposes
Data Source
Figure 1
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AI summary
A gas turbine engine (10) has: a high-pressure turbine (18A); a low-pressure turbine (LPT) (18B) having a LPT outer case (36) and a LPT plenum (92) extending around a central axis (9); a mid-turbine frame (MTF) assembly (28) connecting the low-pressure turbine (18A) and the high-pressure turbine (18B), the MTF assembly (28) having: a MTF outer case (30) defining an inlet (84) for connection to a source of the cooling air, an intermediary plenum (93) fluidly connected to the source of cooling air via the inlet (84), the intermediary plenum (93) having a first air outlet (93B) and a second air outlet (93C), and a MTF plenum (60) disposed radially inwardly of the MTF outer case (30) and fluidly connected to the source of the cooling air via the first air outlet (93B) of the intermediary plenum (93); and a cooling air conduit (96) fluidly connecting the second air outlet (93C) of the intermediary plenum (93) to the LPT plenum (92) while bypassing the MTF plenum (60).