Aircraft Engine Nacelle Thrust Reverser Guide Devices
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Solution Overview
Problem
Current thrust reverser technologies with sliding grids are not suitable for large aircraft nacelles, as the fan cover's downstream edge can come into contact with the grids or mobile cover support during deployment and retraction, due to lack of sufficient guidance and locking mechanisms, which is not effectively addressed by existing solutions that rely on internal stiffness for smaller nacelles.
Innovation Solution
The implementation of a dual-flow aircraft engine nacelle with guiding devices such as U-shaped, O-shaped, and T-shaped tracks and pads that are rigidly connected to the middle and downstream sections, providing comprehensive guidance and locking mechanisms to ensure smooth movement and prevent unwanted contacts between the fan cowl and movable cover during thrust reverser operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fan cover is made free (cantilevered) above the grilles during thrust reverser deployment, then the thrust reverser can be deployed, but the downstream edge of the fan cowl can move under inertia or aerodynamic loading and come into contact with the grilles or mobile cover support
Solution Approach 1:
Guide devices (U-shaped guide shoes, O-shaped guide tracks, T-shaped tracks) are introduced as intermediary elements between the fan cowl and the grilles/mobile cover support. These guide devices constrain the movement of the fan cowl's downstream edge, preventing unwanted contacts while allowing the thrust reverser to deploy. The guide devices act as mediators that control the interaction between moving and stationary components.
2Device complexity
If the internal stiffness of the fan cowl is used to limit movements for smaller nacelles, then the structure remains simple, but this solution cannot be used for large nacelles
Solution Approach 1:
The guide devices are designed to be dynamically engaged or disengaged based on the thrust reverser's position. The guide devices allow freedom of movement during normal operation but engage to provide guidance and prevent contacts during thrust reverser deployment. This dynamic behavior allows the same structure to serve both small and large nacelles effectively.
3Reliability
If guide devices are added to prevent unwanted contacts, then reliability is improved, but device complexity increases
Solution Approach 1:
The guide devices are designed to perform multiple functions simultaneously: they guide the movement of the fan cowl, prevent unwanted contacts with grilles and support, and allow freedom of movement during normal operation. By making the guide devices multi-functional, the patent reduces the need for separate components for each function, thereby limiting the increase in overall device complexity.
Data Source
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AI summary
The invention concerns a nacelle of an aircraft turbofan engine comprising an air inlet (2) upstream from the engine, a median section (4) intended to surround a fan (5) of the engine and delimited on the outside by a fan cowl (6) supported by a fan housing to which it is attached at the upstream portion, a downstream section delimiting an annular flow path in which the air is intended to flow and housing thrust reversal means, the thrust reversal means comprising a movable cowl (9) associated with at least one actuator for moving the movable cowl between a direct jet position, in which it ensures the aerodynamic continuity of the nacelle and an indirect jet position in which it opens up a passage in the nacelle by uncovering gratings arranged around this flow path that receive the cold air flow to return it towards the outside and forwards, the gratings being attached to the movable cowl and sliding with same, the nacelle being characterised in that it comprises a series of guiding devices (16,17,18) distributed around a longitudinal axis (Δ) of the nacelle, and each comprising a first guide element (20, 23, 27) secured to the median section and a second guide element (19, 22, 24) secured to the downstream section.