Thrust Reverser Obturator Membrane for Aerodynamic Disturbance Reduction
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Solution Overview
Problem
Existing thrust reversers with sealing flaps in aircraft propulsion units cause aerodynamic disturbances and limit acoustic panel installation due to recesses and flaps, leading to inefficiencies in deployment and protection of the secondary flow duct.
Innovation Solution
A thrust reverser design incorporating obturator membranes with a mobile frame that deploys and seals the secondary flow duct, using a pivotingly mounted mobile frame and optional mechanical or inflatable mechanisms for easy deployment and improved aerodynamic and acoustic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing flaps are used in the thrust reverser, then the secondary flow duct can be sealed when deployed, but aerodynamic disturbances occur and acoustic panel installation is limited due to recesses and flaps
Solution Approach 1:
The patent replaces rigid sealing flaps with a flexible obturator membrane that can be stored flat against the radially internal wall during direct thrust and deployed to seal the secondary flow duct during reverse thrust. This flexible membrane eliminates the need for recesses and protruding flaps, removing aerodynamic disturbances while maintaining effective sealing.
Solution Approach 2:
The sealing function is achieved by deploying the membrane in the radial dimension rather than using flaps that protrude into the flow path. The membrane transitions from a two-dimensional flat state stored against the wall to a three-dimensional deployed state that seals the duct, eliminating the need for recesses that cause aerodynamic issues.
2Object-generated harmful factors
If obturator membranes are used to replace sealing flaps, then aerodynamic performance and acoustic treatment are improved, but deployment complexity increases
Solution Approach 1:
The obturator membrane is designed to deploy automatically using the existing axial movement of the mobile structure. As the mobile structure translates axially during reverser deployment, the membrane is passively pulled from its stored position against the radially internal wall into its deployed sealing position, eliminating the need for separate actuators or complex deployment mechanisms.
Solution Approach 2:
The membrane is pre-positioned and stored in a compact state against the radially internal wall during direct thrust configuration. This preliminary positioning allows for rapid, simple deployment when the reverser transitions to reverse thrust, as the membrane is already in place and only needs to be pulled into its functional position.
3Ease of operation
If recesses are provided in the radially internal wall for sealing flaps, then flaps can be received in retracted position, but acoustic panel installation is locally limited and aerodynamic disturbances occur
Solution Approach 1:
The flexible obturator membrane replaces rigid flaps that require recesses for retraction. The membrane can be stored flat against the radially internal wall without requiring any recesses or protruding structures, thereby preserving the full surface area for acoustic panel installation and eliminating aerodynamic disturbances caused by recess geometry.
4Reliability
If mobile sealing flaps are used, then the secondary flow duct can be sealed, but weight and complexity increase compared to simpler mechanisms
Solution Approach 1:
The obturator membrane is constructed as a lightweight flexible film rather than a rigid flap structure. This dramatically reduces the weight of the moving sealing component while maintaining its ability to effectively seal the secondary flow duct during reverse thrust operation.
Solution Approach 2:
The membrane utilizes the existing axial movement of the mobile structure for its deployment, rather than requiring separate actuators, motors, or complex mechanical systems. This self-deploying mechanism significantly reduces the weight and complexity of the sealing system compared to actively controlled flap systems.
Data Source
AI summary
A thrust reverser for an aircraft propulsion unit, including a fixed structure equipped with a wall for radially internally delimiting a secondary flow duct, and a mobile structure including at least one reverser mobile cowl equipped with a reverser-cowl radially internal wall, the mobile structure being movable between a forward direct-thrust position and a retreated reverse-thrust position, the thrust reverser also including at least one obturator membrane designed to deflect at least some of the secondary flow towards the cascade vanes when the mobile structure is in the retreated reverse-thrust position. The reverser can include a mobile frame for deploying the obturator membrane, this frame being mounted with the ability to pivot on the mobile structure of the reverser between a retracted position and a position in which it is deployed in the secondary flow duct.