Rotatable Exhaust Plug Liner for Gas Turbine Thrust Reversal
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Solution Overview
Problem
Large aircraft equipped with high bypass gas turbine engines face challenges in reducing the size and weight of fan thrust reversers, which are necessary to overcome both forward momentum and core thrust during landing, leading to increased costs and complexity.
Innovation Solution
A gas turbine engine design featuring a rotatable exhaust plug liner with a non-uniform outer surface, including protrusions and recesses, that increases the cross-sectional area of the exhaust pathway during thrust reversal, reducing the core thrust component by increasing the expansion ratio across the turbine section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the fan thrust reverser size is reduced to lower costs, then initial and operating costs decrease, but the ability to overcome core thrust and forward momentum during landing is compromised
Solution Approach 1:
The exhaust plug liner is rotated to different angular positions to change the cross-sectional area of the exhaust pathway. This parameter change in exhaust flow area directly modifies the core thrust output, allowing the system to adapt thrust levels without changing the physical size of the thrust reverser components.
Solution Approach 2:
The exhaust plug liner is made rotatable relative to the exhaust plug, transforming a static exhaust system into a dynamic one. This rotational capability allows real-time adjustment of exhaust pathway area, enabling the system to optimize performance across different operating conditions (cruise vs. thrust reversal) without requiring oversized components for peak reverse thrust scenarios.
2Force
If the exhaust pathway cross-sectional area is increased during thrust reversal, then core thrust is reduced and thrust reverser size can be smaller, but the device complexity increases due to the rotatable liner mechanism
Solution Approach 1:
The exhaust plug is segmented into two independent rotatable components: the exhaust plug liner and the exhaust plug itself. This segmentation allows each component to be controlled independently, with the liner rotating to adjust exhaust pathway area and the plug rotating to align apertures with the exhaust pathway. This modular segmentation simplifies the control mechanism compared to a single complex movable component.
Solution Approach 2:
The exhaust plug liner is nested within the exhaust plug, with the liner positioned along the inner surface of the exhaust plug. This nested configuration allows the liner to rotate independently while being contained within the plug structure, reducing overall space requirements and simplifying the mechanical arrangement compared to side-by-side or externally-mounted adjustment mechanisms.
3Force
If the exhaust plug liner is made rotatable to adjust exhaust pathway area, then core thrust can be reduced, but manufacturing precision requirements increase for the non-uniform outer surface alignment
Solution Approach 1:
The exhaust plug liner features a non-uniform outer surface with specific geometric features (protrusions and recesses) at particular axial locations. These localized geometric variations are designed to align with corresponding features in the exhaust plug apertures, creating defined alignment references that guide the rotation and positioning process, thereby reducing the overall manufacturing precision requirements for the entire component.
Solution Approach 2:
The exhaust plug liner employs an asymmetric non-uniform outer surface design rather than a uniform cylindrical shape. This asymmetry creates unique alignment characteristics where specific protrusions and recesses must match corresponding features in the exhaust plug, providing natural mechanical alignment cues that simplify the positioning and rotation process while maintaining precise control over the exhaust pathway area.
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 design reduces the size and weight of fan thrust reversers by lowering the core thrust component, thereby decreasing the initial and operating costs of the aircraft while effectively slowing and stopping the aircraft during landing.
Implementation Method 1
increasing the expansion ratio across the turbine section
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An exhaust section (78) of a gas turbine engine includes an exhaust plug (58) defining a plurality of exhaust plug apertures (92) circumferentially spaced from each other. Also included is an exhaust nozzle (60) radially offset from the exhaust plug defining an exhaust pathway (80) between the exhaust plug and the exhaust nozzle. Further included is an exhaust plug liner (59) having a non-uniform outer surface (94) axially aligned with the exhaust plug apertures. The exhaust plug liner is rotatable relative to exhaust plug between a first position and a second position to selectively change a cross-sectional area of the exhaust pathway (80) during thrust reversal operation to increase an amount of reverse thrust.