Pivotable Thrust Reverser Vanes for Nacelle Thickness Reduction
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Solution Overview
Problem
Aircraft gas turbine engine nacelles with thrust reversers face challenges due to the large radial thickness of vanes, which increases aerodynamic drag in normal flight and requires a design that minimizes thickness while maintaining effective airflow turning capabilities.
Innovation Solution
The design incorporates pivotable thrust reverser vanes with a fixed structure, allowing the vanes to occupy a smaller volume when stowed and expand when deployed, with a subset of fixed vanes downstream to manage airflow and reduce forces on the pivotable vanes, enabling efficient airflow redirection and reduced nacelle thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vanes have a relatively large radial thickness to prevent turbulence, then the airflow turning effectiveness is improved, but the overall thickness of the nacelle increases and aerodynamic drag increases
Solution Approach 1:
The patent applies the dynamics principle by making the vanes pivotable between a deployed position (where they provide effective airflow turning) and a stowed position (where they minimize radial thickness and aerodynamic drag). This dynamic configuration allows the system to adapt its geometry based on operational requirements, resolving the contradiction between needing thick vanes for effective airflow control and thin vanes to reduce drag.
Solution Approach 2:
The thrust reverser system is segmented into multiple functional components: fixed vanes, pivotable vanes, blocker doors, and a movable sleeve. This segmentation allows different parts to perform specialized functions - the fixed vanes provide structural support and baseline airflow control, while the pivotable vanes provide adjustable airflow redirection only when needed, thereby reducing overall radial thickness and drag.
2Strength
If the vanes have a relatively large radial thickness to maintain structural integrity and prevent turbulence, then the airflow control capability is improved, but the nacelle overall thickness increases
Solution Approach 1:
By making the vanes pivotable rather than fixed, the system achieves structural integrity only when needed (in deployed position) while minimizing nacelle thickness in the stowed position. The dynamic deployment allows the structure to be thin 90% of the time while maintaining strength during the 10% of operation when thrust reversal is active.
Solution Approach 2:
The patent resolves the thickness contradiction by utilizing the angular dimension through pivotable movement. Instead of increasing radial thickness to achieve both strength and compactness, the solution uses angular deployment to provide strength only when required, effectively using a different dimension (angular position) to solve the radial thickness problem.
3Object-affected harmful factors
If pivotable vanes are used to reduce nacelle thickness, then the aerodynamic drag is reduced, but the complexity of the thrust reverser mechanism increases
Solution Approach 1:
The patent merges multiple functions into integrated components. The pivotable vanes combine airflow redirection, structural support, and drag reduction functions. The movable sleeve integrates with the blocker doors to simultaneously control both the hot and cold stream flows. This merging reduces the number of separate mechanisms needed, thereby reducing overall complexity despite the pivotable feature.
Solution Approach 2:
The pivotable vanes are designed to be actuated by the movement of the sleeve and blocker doors themselves, rather than requiring separate actuation mechanisms. The structural movement of the thrust reverser components provides the actuation force for the vanes, making the system self-servicing and reducing the need for additional complex actuation systems.
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 reduces nacelle thickness, minimizes aerodynamic drag, and allows for effective airflow turning, while the pivotable vanes are more easily actuated, providing reliable and cost-effective thrust reversal with reduced weight and increased efficiency.
Implementation Method 1
a plurality of thrust reverser vanes configured to direct bypass air forwardly
Implementation Method 2
the vanes have a relatively large radial thickness, which may increase the overall thickness of the nacelle, and so increase aerodynamic drag in normal flight
Data Source
Figure 1~2
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Figure 6~7
AI summary
An aircraft gas turbine engine nacelle (21) comprising a thrust reversal arrangement (23). The thrust reversal arrangement (23) comprises at least one thrust reverser cascade box (28) comprising a fixed structure (30) and a plurality of thrust reverser vanes (29, 31) configured to direct bypass air forwardly. At least a subset of the thrust reverser vanes (31) are pivotable and / or translatable relative to the fixed structure (30) between a deployed position, in which the vanes (31) define a first volume, and a stowed position, in which the pivotable vanes (31) define a second, smaller volume.