Aircraft Nacelle Thrust Reversal Downstream Deflector
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Solution Overview
Problem
The existing thrust reversal devices in aircraft nacelles are inefficient due to the significant mass of cascades of vanes and the need to reinforce the nacelle to prevent air stream impact, which increases the overall mass and reduces efficiency.
Innovation Solution
The proposed solution involves an aircraft nacelle with a thrust reversal device that includes a lateral opening, a movable part, a deflection system, and an orientation system. The orientation system comprises a support with crossmembers, transverse deflectors extending between these crossmembers, and a downstream deflector positioned at the lateral opening's downstream edge, which deflects the air stream away from the nacelle's outer wall, reducing the need for reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cascades of vanes are used to orient the air stream outward and upstream, then the air stream orientation function is achieved, but the mass of the orientation system increases significantly
Solution Approach 1:
The orientation system is segmented into multiple independent deflectors (first deflector, second deflector, third deflector) positioned at different locations. Each deflector handles a specific portion of the air stream orientation task, allowing the system to achieve the same functional effect with lighter individual components compared to a single massive cascade structure.
Solution Approach 2:
The invention transitions from using multiple vanes arranged in cascades (one-dimensional stacking) to using deflectors positioned at multiple spatial locations around the nacelle (three-dimensional distribution). This dimensional change allows the air stream to be oriented through distributed deflection points, reducing the mass concentration in any single location.
2Strength
If the nacelle is reinforced to prevent air stream impact on the downstream edge, then structural integrity is maintained, but the overall mass of the nacelle increases
Solution Approach 1:
The invention converts the potentially harmful air stream impact on the downstream edge into a beneficial orientation mechanism. The third deflector, positioned at the downstream edge, actively uses the air stream flow to orient it upstream and outward, transforming what would be a damaging impact into a useful aerodynamic function that also protects the structure.
Solution Approach 2:
The third deflector acts as an intermediary element between the air stream and the downstream edge of the nacelle. Instead of allowing the air stream to directly impact and damage the downstream edge (requiring reinforcement), the deflector intercepts and redirects the flow, mediating the interaction and eliminating the need for structural reinforcement.
3Weight of moving object
If transverse deflectors extend over the entire height of the opening, then the orientation system mass is reduced, but the manufacturing complexity increases
Solution Approach 1:
The deflectors are implemented as thin-walled structures that extend over the entire height of the opening. This allows them to achieve the necessary aerodynamic surface area for effective air stream orientation while maintaining low mass. The thin-film approach provides sufficient structural integrity for the aerodynamic loads while minimizing material usage.
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
This configuration reduces the mass of the orientation system by using large transverse deflectors that extend over the entire height of the opening and eliminates the need for reinforcing the nacelle, thereby enhancing the efficiency and reducing the overall mass of the thrust reversal device.
Implementation Method 1
a downstream deflector positioned at the downstream edge of the lateral opening and configured to deflect the air stream deflected by the deflection system toward the upstream end of the nacelle
Implementation Method 2
at least one transverse deflector positioned approximately in a plane perpendicular to the longitudinal direction and configured to orient the air stream deflected by the deflection system toward the upstream end of the nacelle
Implementation Method 3
a deflection system configured to occupy a retracted position, when the thrust reversal device is in the inactivated state, in which the deflection system does not interfere with the air stream, and a deployed position, when the thrust reversal device is in the activated state, in which the deflection system interferes with the air stream and orients it toward the lateral opening
Data Source
AI summary
An aircraft nacelle equipped with a thrust reversal device which comprises: at least one deflection system configured to deflect an air stream channeled in the nacelle toward a lateral opening of the nacelle, in the activated state; at least one orientation system having: at least one transverse deflector configured to orient the air stream deflected by the deflection system toward the upstream end of the nacelle, at least one downstream deflector positioned at the downstream edge of the lateral opening and configured to deflect the air stream deflected by the deflection system toward the upstream end of the nacelle.