Aircraft Engine Thrust Reverser Inclined Cowl Translation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thrust reverser structures for aircraft engines, particularly those using 'natural blockage' methods, face challenges in balancing weight reduction, fuel efficiency, and forward thrust performance due to increased surface area and pressure losses in the by-pass fan duct, which become more significant as engine size increases.
Innovation Solution
The thrust reverser system employs a translating cowl with two diametrically opposite portions moving at an angle to the engine axis, optimizing the by-pass fan duct aerodynamics and using canted cascades or alternative aerodynamic devices to minimize weight and deployment stroke, while maintaining reverse thrust efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 'natural blockage' thrust reverser is used with a pronounced curved contour in the by-pass fan duct, then reverse thrust efficiency is improved, but surface area increases causing pressure losses that reduce forward thrust performance and increase fuel burn
Solution Approach 1:
The cowl is designed to translate along an inclined path rather than a fixed curved contour, dynamically adjusting the blockage position to achieve reverse thrust without permanently altering the duct geometry, thereby avoiding continuous pressure losses during forward flight
Solution Approach 2:
The translation path of the cowl is inclined at a specific angle (5-20 degrees) to the engine axis, changing the geometric parameter of the blockage mechanism to achieve effective reverse thrust while minimizing impact on forward thrust aerodynamics
2Reliability
If blocker doors with articulated linkage are used to block the by-pass duct, then reverse thrust is achieved, but device complexity and weight increase
Solution Approach 1:
The complex articulated linkage mechanism and blocker doors are completely removed from the system. Instead, a simple translating cowl structure is used that blocks the by-pass duct through its own translation motion, eliminating the need for separate blocking mechanisms
Solution Approach 2:
The cowl serves dual functions: it provides aerodynamic fairing during forward flight and acts as the blocking mechanism during reverse thrust, eliminating the need for dedicated blocker doors and their complex linkage systems
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A power unit (10) for an aircraft for providing propulsive thrust by means of a flow of gaseous fluid (18) is described, the power unit comprising an efflux duct (34) defining a first fluid flow path along which said gaseous fluid travels for discharge from a first fluid exit opening (36) to provide said propulsive thrust; the power unit having a thrust reversing structure (38) which, when in an operative deployed position, redirects the flow of gaseous fluid along a second fluid flow path to discharge from a second fluid exit opening (78) to provide reverse thrust; the thrust reversing structure comprising longitudinally translating cowl portions (50, 52) which are moveable from a first stowed position to a second deployed position and in which second deployed position an internal form(62) of said cowl portions block a major proportion of said first fluid exit opening to cause gaseous fluid efflux from said second fluid exit opening, the thrust reversing structure being characterised in that said cowl portions move in a generally longitudinal. direction towards the deployed position along a path which is inclined to the power unit axis (71).