Aircraft Nacelle Guide System for Thrust Reversal Force Absorption
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Solution Overview
Problem
Turbojet engine nacelles with O-duct or C-duct structures experience non-uniform lateral force distribution during thrust reversal, leading to parasitic distortions and pendulum movements due to non-uniform cold flow redirection, which results in oval deformation of the thrust reverser.
Innovation Solution
A guide system secured to the movable cowl, cooperating with a crosshead fixed relative to the nacelle, is introduced in the 'six o'clock' position to absorb lateral strains, replacing a solid cascade and ensuring correct force absorption while minimizing hyperstatism risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a guide system is added to absorb lateral strains, then structural integrity is improved, but device complexity increases
Solution Approach 1:
The guide system is segmented into multiple guide rails distributed around the nacelle perimeter, with each rail independently absorbing lateral forces. This segmentation allows the complex force absorption function to be distributed across simpler, modular components rather than requiring a single complex structure.
Solution Approach 2:
The guide system acts as an intermediary between the movable cowl and the fixed nacelle structure. It mediates the lateral forces generated during thrust reversal by providing guided translation paths, thereby protecting the main structural components from parasitic distortions and oval deformations.
2Ease of manufacture
If the sliding cowl is mounted only at the upper slides near the twelve o'clock position, then ease of manufacture is improved, but reliability deteriorates due to non-uniform force distribution
Solution Approach 1:
Guide rails are added at specific locations (lower and lateral positions) where lateral forces are generated during thrust reversal, rather than uniformly distributing support. This local reinforcement approach maintains manufacturing simplicity while improving reliability by placing guidance only where mechanically necessary.
Solution Approach 2:
The guide rail configuration is asymmetric, with rails positioned at the lower and lateral periphery of the nacelle where thrust reversal forces are most pronounced. This asymmetric placement optimizes force absorption without requiring symmetric reinforcement throughout the entire structure.
Data Source
AI summary
The present disclosure relates to an aircraft turbojet engine nacelle, the nacelle including a rear section without a lower bifurcation, the rear section including a thrust reversal system, the thrust reversal system including a mobile cowl. The nacelle includes a guide system that translates as one with the mobile cowl, the guide system collaborating with at least one slide that is fixed in relation to the nacelle, the guide system and the slide being arranged near the position referred to as the 6 o'clock position.