Aircraft Engine Nacelle Variable Nozzle Section Design
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Solution Overview
Problem
Existing aircraft engine nacelles with variable section nozzles suffer from mechanical weakening and vibrations due to the mechanical connection between the mobile annular downstream part and the upstream part of the cowl, which affects the thrust reverser and nozzle performance.
Innovation Solution
A nacelle design featuring a thrust reverser cowl with a single-piece upstream section covering deflection means and a downstream nozzle section, incorporating a movable escape door that slides or pivots to vary the nozzle section, and an actuator system for controlled movement, with locking and sealing mechanisms to ensure structural integrity and aerodynamic continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical connection is used between the mobile annular downstream part and the upstream part of the cowl to enable nozzle section variation, then the nozzle section can be effectively varied, but the structural strength of the cowl is weakened and vibrations are generated
Solution Approach 1:
The cowl is divided into independent functional components: a fixed upstream part and a mobile downstream part with annular escape doors. The escape doors can move independently to vary the nozzle section without requiring a mechanical connection between the upstream and downstream parts, thus maintaining structural strength while enabling adaptability.
Solution Approach 2:
The escape doors are designed to be movable between closed and open positions, allowing dynamic adjustment of the nozzle section. This dynamic capability is achieved through independent actuation of the escape doors rather than through mechanical connection of the cowl parts, eliminating vibrations while preserving strength.
2Adaptability or versatility
If the escape door is made movable to vary the nozzle section, then the nozzle section can be adapted to different flight phases, but the device complexity increases
Solution Approach 1:
The mobile downstream part with escape doors serves multiple functions: it acts as both the nozzle boundary and the actuating mechanism for section variation. The escape doors themselves are the moving elements that control the nozzle section, eliminating the need for separate actuation mechanisms and reducing overall device complexity.
Data Source
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AI summary
The invention concerns a nacelle (10) for an aircraft engine, comprising a thrust reverser cowling (20) that is slidably mounted between a direct jet position, and a reversed jet position in which the cowling (20) opens a passage in the nacelle (10) and uncovers the deflection means, and a drive means for moving the cowling (20), characterised in that the nozzle section (30) of the cowling (20) delimits at least one opening (36) that is combined with an escape door (38), the escape door (38) being movably mounted on the cowling (20) between a closed position in which the door (38) engages with the associated opening (36) to counteract the flow of air through said opening (36), and an open escape position in which the door (38) is retracted to allow a portion of the air flow to flow through said opening (36).