Turbine Exhaust Case Mixer Hub Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing turbine exhaust case (TEC) mixer assemblies in turbofan aircraft engines face challenges due to thermal cycling, which causes thermal stress and reduces the lifespan of components. Additionally, access for installation or repair is difficult due to the interconnected nature of the components.
Innovation Solution
The TEC mixer assembly incorporates a design with removably coupled hub sections and an axial spring that allows for thermal expansion and contraction, reducing thermal stress. This design also includes struts that interconnect the mixer and the hub, providing greater accessibility for maintenance and repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If TEC and mixers are interconnected through struts to form a rigid structure, then structural strength is improved, but thermal stress increases due to differential thermal expansion and contraction
Solution Approach 1:
The patent changes the physical state of the connection between hub sections from rigid to flexible by introducing axial springs. These springs allow the connection to accommodate thermal expansion and contraction by changing their compression state, thereby reducing thermal stress while maintaining structural integrity.
Solution Approach 2:
The patent introduces dynamic elements (axial springs) that can compress and expand in response to thermal cycles. This dynamic capability allows the structure to adapt to temperature changes, reducing thermal stress while maintaining the necessary structural strength during operation.
2Stability of the object's composition
If TEC mixer components are tightly interconnected, then structural stability is improved, but accessibility for installation and repair deteriorates
Solution Approach 1:
The patent divides the hub into multiple removable hub sections that can be separated from each other. This segmentation allows maintenance personnel to access internal components by removing sections, while the sections themselves remain interconnected through axial springs during normal operation to maintain structural stability.
Solution Approach 2:
The axial springs serve as intermediaries between hub sections, allowing the sections to be connected during operation for structural stability but separable during maintenance. The springs maintain the connection while permitting the sections to be removed when needed for accessibility.
3Reliability
If axial springs are used to accommodate thermal expansion, then thermal stress is reduced, but device complexity increases
Solution Approach 1:
The axial springs utilize the simple physical principle of elastic deformation to accommodate thermal expansion. This is a well-understood mechanical concept that adds minimal complexity compared to more sophisticated thermal management systems, while effectively reducing thermal stress.
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 effectively mitigates thermal stress and extends the lifespan of components by allowing for differential thermal expansion and contraction. Additionally, the modular design enhances accessibility for installation and maintenance, improving overall operational reliability.
Implementation Method 1
The large temperature gradients to which TEC and mixers are exposed can cause their respective components to undergo significant thermal cycling (thermal expansion and shrinkage)
Implementation Method 2
an axial spring that allows for thermal expansion and contraction, reducing thermal stress
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
The turbine exhaust case (TEC) mixer assembly for an aircraft engine includes a center body (30) including a hub (31) that encloses a center body cavity (32) and has a first wall portion (31A) and a second wall portion (31B) that are axially spaced apart. The first and second wall portions (31A, 31B) have axial end segments which are removably coupled to each other radially inwardly from an outer periphery (34) of the center body (30) via a fixing arrangement including a fastener that is enclosed within the center body cavity (32). An axial spring (50) includes a gap axially defined between portions of the axial end segments and located at the outer periphery (34) of the center body (30). A mixer (29) extends peripherally about the center body (30) and is spaced radially outward from the hub (31) by a plurality of struts (40) extending between the hub (31) and the mixer (29), the plurality of struts (40) being axially offset from the gap at a strut-hub interface (41).