Fixed-Cascade Thrust Reverser Membrane for Aerodynamic Flow Control
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Solution Overview
Problem
Existing thrust reversers with shutters in aircraft propulsion systems suffer from aerodynamic disturbances and limitations in acoustic performance due to the presence of recesses and flaps, which also complicate implementation and reliability of deployment.
Innovation Solution
The use of sealing membranes attached to a fixed structure and a movable structure within the thrust reverser, with attachment means connecting one end to a rear support frame and the other end to a radially internal wall, providing improved aerodynamic and acoustic performance by eliminating geometric singularities and enhancing deployment reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If shutters with recesses and flaps are used to divert secondary flow, then the secondary flow can be redirected towards the deflection grids, but aerodynamic disturbances and drag increase due to geometric singularities
Solution Approach 1:
The patent replaces rigid shutters with recesses and flaps with a flexible sealing membrane that has no geometric singularities. The membrane is attached at its ends to the fixed structure and mobile structure, allowing it to flex and seal the secondary flow passage effectively without creating aerodynamic disturbances or drag-inducing geometric features.
2Reliability
If recesses and flaps are installed in the radially internal wall, then shutter deployment is possible, but acoustic panel installation is locally limited
Solution Approach 1:
The sealing membrane replaces the need for recesses and flaps, providing a smooth continuous surface on the radially internal wall that allows full coverage with acoustic panels while maintaining reliable secondary flow sealing through the flexible membrane's ability to conform and seal against the mobile structure.
3Object-generated harmful factors
If sealing membranes are used to replace shutters, then aerodynamic performance and acoustic treatment are improved, but implementation complexity and deployment reliability may be compromised
Solution Approach 1:
The patent simplifies membrane implementation by attaching the sealing membrane only at its two ends - one end to the fixed structure and the other end to the mobile structure. This minimal attachment approach reduces manufacturing complexity while the membrane's flexibility ensures reliable deployment and sealing without requiring complex mounting mechanisms throughout its surface.
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 sealing membranes offer simplified implementation, high deployment reliability, and improved aerodynamic and acoustic performance by eliminating drag-inducing geometric singularities, resulting in a smoother airflow and reduced acoustic disturbances.
Implementation Method 1
designed to deflect at least part of the secondary flow towards the passage opening and the deflection grid, when the mobile structure is in the retracted thrust reversal position
Data Source
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Figure 3~3A
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AI summary
The invention relates to a thrust reverser (30) for an aircraft propulsion assembly, comprising a fixed structure (31) equipped with at least one cascade (32) as well as a radially inner delimiting wall (18) of a secondary vein (21B), and a movable structure (29) comprising at least one reverser cowling (33), the cascade (32) being arranged, in the forward direct thrust position, in a housing (54) of the reverser cowling, and, in the retracted thrust reversal position, the wall (52) reveals a passage opening (56) of the secondary vein towards the cascade, the thrust reverser also comprising at least one sealing membrane (58) designed to deflect at least one portion of the secondary flow. Hook means are provided for securing the membrane to a rear cascade support frame, and to the radially inner delimiting wall (18) of the secondary vein.