Aircraft Thrust Reverser Cascade Positioning for Aerodynamic Disturbance Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thrust reversal systems in aircraft turbomachines experience aerodynamic disturbances and pressure losses in the secondary duct during the inactive configuration, leading to decreased performance due to the interaction between the mobile outer cowling and reverser doors.
Innovation Solution
The system incorporates a second thrust reversal cascade that is positioned outside the secondary duct in the inactive configuration, which moves rearward and intrudes into the duct in the active configuration, reducing airflow disturbances and using a control lever and guide rail mechanism for synchronized movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If reverser doors are positioned within the secondary duct in inactive configuration, then the thrust reverser system is compact and integrated, but aerodynamic disturbances and pressure losses occur in the secondary duct
Solution Approach 1:
The second cascade is extracted from the secondary duct in the inactive configuration and positioned in a housing space outside the duct. This removes the source of aerodynamic disturbance from the airflow path while maintaining the ability to intrude into the duct when activation is required
Solution Approach 2:
The second cascade is designed to be movable between two positions: retracted outside the secondary duct in inactive configuration, and intruded into the secondary duct in active configuration. This dynamic positioning allows the system to optimize aerodynamic performance during normal operation while maintaining thrust reversal capability when needed
2Ease of operation
If mobile outer cowling is displaced rearwards to activate reverser doors, then thrust reversal function is achieved, but aerodynamic disturbance increases during transition
Solution Approach 1:
The second cascade is taken out of the secondary duct during inactive configuration, eliminating the interaction between the mobile outer cowling and the cascade structure during normal airflow, thereby reducing aerodynamic disturbance during transition phases
Solution Approach 2:
The control lever with guide rail acts as an intermediary mechanism that enables the second cascade to move from its retracted position to its intruded position within the secondary duct, facilitating smooth transition without direct interference from the mobile outer cowling
3Object-affected harmful factors
If second cascade is positioned outside secondary duct in inactive configuration, then airflow disturbance is minimized, but device complexity increases
Solution Approach 1:
The control lever mechanism merges multiple functions: it connects the second cascade to the guide rail, enables pivoting motion, and coordinates with the actuator system. This integration reduces the need for separate complex positioning mechanisms while achieving the desired cascade movement
Solution Approach 2:
The second cascade is positioned in a housing space that is spatially separated from the secondary duct in the inactive configuration, utilizing the third dimension (radial position) to resolve the conflict between aerodynamic performance and thrust reversal functionality
Data Source
AI summary
A thrust reverser system includes two thrust reversal cascades, of which the first cascade is entrained by an actuator, and which are configured to adopt a retracted position in which they are housed in a space located outside the duct. The action of the actuator brings about: rearward displacement of the first cascade in the direction of a nacelle opening; and during part of the rearward displacement of the second cascade, simultaneous pivoting of this second cascade under the action of a control lever, the interaction of which with a fixed guide rail forces the front end of the lever to move radially inwards while the lever is entrained rearwards by the second cascade.