Translating Cowl Thrust Reverser Efflux Management
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Solution Overview
Problem
Current single cascade thrust reverser systems do not effectively control engine exhaust airflow (efflux) when deployed, leading to issues like hot gas impingement on the aircraft, potential damage, and adverse effects on single engine landing/yaw control, as well as insufficient nose-down weight for controllability.
Innovation Solution
A translating cowl thrust reverser system with efflux management, comprising a support structure, transcowl, cowl shield, and single cascade structure, where the transcowl is movable between stowed and deployed positions, forming an aperture, and featuring a cowl shield with turning vanes and a single cascade structure with internal and external turning vanes, directing airflow perpendicular to the aircraft fuselage to manage efflux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a single cascade thrust reverser is used to reduce weight and manufacturing cost, then weight and manufacturing cost are reduced, but efflux control is lost
Solution Approach 1:
The single cascade structure is segmented into multiple functional zones with different turning vanes (internal and external) that can be independently configured. The cowl shield is divided into multiple vanes that work in coordination with the cascade structure to create zones of different airflow deflection, enabling both weight reduction and efflux control
Solution Approach 2:
Different portions of the thrust reverser are given different local qualities through the internal and external turning vanes. The internal turning vanes handle core exhaust flow while external turning vanes handle fan airflow, creating localized airflow control zones that manage efflux direction without requiring a complete redesign of the entire reverser system
2Device complexity
If efflux is not controlled, then the thrust reverser structure is simpler, but hot gas impingement on the empennage occurs
Solution Approach 1:
The cowl shield acting as an intermediary component between the exhaust source and the empennage. It intercepts and redirects hot exhaust gases through the turning vanes before they can reach the empennage, preventing direct impingement while maintaining a relatively simple overall structure
Solution Approach 2:
The turning vanes redirect exhaust airflow from a radial outward direction to a downward direction, changing the flow dimension. This dimensional redirection moves the efflux away from the empennage area while maintaining structural simplicity
3Object-generated harmful factors
If efflux is only controlled on the aircraft side of the engine, then efflux control is achieved, but single engine landing/yaw control is adversely impacted
Solution Approach 1:
The system changes the spatial distribution parameters of the efflux by using multiple turning vanes with different angles and positions. This creates a controlled efflux pattern that maintains yaw control authority while preventing hot gas impingement, allowing balanced performance across different operating conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively controls and redirects engine exhaust airflow, preventing damage and ensuring safe single-engine landing and yaw control while meeting performance requirements by directing efflux vertically away from the aircraft.
Implementation Method 1
the thrust reverser typically redirects at least a portion of the airflow (from the engine fan and/or core exhaust) forward and radially outward, through one or more cascade vanes, to help decelerate the aircraft
Implementation Method 2
The curved vane has a curved vane inner surface and a curved vane outer surface, and the curved vane inner surface faces the forward wall. The internal turning vanes are disposed within the airflow gap and are spaced apart from each other. Each internal turning vane is coupled to, and extends between, the forward wall and the curved vane inner surface
Data Source
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AI summary
A translating cowl thrust reverser system with efflux management includes a support structure, a transcowl, a cowl shield, and a single cascade structure. The transcowl and cowl shield are moveable together between a first position, in which the transcowl abuts the support structure, and a second position, in which an aperture is formed between the transcowl and the support structure. The cowl shield has cowl shield turning vanes. The single cascade structure is disposed within the aperture and includes a forward wall, a curved vane, internal turning vanes, and external turning vanes. In the first position, each cowl shield turning vane is disposed between a different pair of external turning vanes. The cowl shield turning vanes, the internal turning vanes, and the external turning vanes turn the airflow so that it is directed substantially perpendicular to, and vertically outboard relative to, a plane of symmetry.