Thrust Reverser Cascades Integrated in Movable Cowls
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thrust reversers for aircraft nacelles with cascades and flaps integrated in movable cowls face congestion issues due to limited dimensions, leading to suboptimal aerodynamic performance and increased mass and consumption.
Innovation Solution
A thrust reverser design where cascades are partially integrated into movable cowls, with an actuation system allowing shorter stroke movement of cascades relative to cowls, using a control mechanism that connects both to the cowls and cascades, and includes features like guiding pins, connecting rods, and sealing gaskets to enhance integration and reduce flow leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If cascades are fully integrated in movable cowls, then aerodynamic performance is improved, but radial thickness of cowls increases
Solution Approach 1:
The cascade structure is segmented into multiple parts: a fixed portion integrated in the front frame and a movable portion integrated in the movable cowl. This segmentation allows the cascade to achieve full integration for aerodynamic performance while the movable portion can be extracted from the cowl during operation, avoiding increased radial thickness.
Solution Approach 2:
The movable portion of the cascade is nested within the movable cowl during closed position, achieving full integration. During opening, the movable portion is extracted from the cowl, allowing the cowl to maintain its original thickness without permanent increase.
2Reliability
If cascades and flaps with control systems are integrated in movable cowls, then thrust reversal effectiveness is improved, but device complexity increases
Solution Approach 1:
The control mechanisms for both the cascade and the flap are merged into a single integrated control system. The actuator rod connects to both the cascade control lever and the flap control lever, allowing simultaneous control of both components through a single actuation action, thereby reducing overall system complexity.
3Ease of operation
If connecting rods pass through cold air flow to connect flaps to fixed structure, then flap control is achieved, but aerodynamic performance deteriorates
Solution Approach 1:
The connecting rod and its associated control elements are extracted from the cold air flow path. Instead of passing through the flow, the control mechanism is integrated within the movable cowl structure, eliminating the harmful intrusion into the aerodynamic flow while maintaining flap control functionality.
Solution Approach 2:
A guiding pin acts as an intermediary element that transmits the control motion from the cascade to the flap without requiring the connecting rod to pass through the cold air flow. The guiding pin is positioned within the cowl structure, mediating the control function while preserving aerodynamic performance.
Data Source
AI summary
A thrust reverser for a turbojet engine nacelle includes movable cowls which move backward relative to a front frame under the action of an actuation system, thereby making flaps tilt, via a control mechanism, so as to substantially close the annular cold air flow path, and by opening cascades disposed around this flow path and which receive the cold air flow and return it forward. When the thrust reverser is closed, the cascades are partially integrated in the cowls, and the thrust reverser includes an actuation system which makes the cascades move backward along a stroke which is shorter than the stroke of the cowl.