Thrust Reverser Blocker Door Mechanism for Drag Reduction
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Solution Overview
Problem
Existing thrust reversers for aircraft, particularly those with bypass duct configurations, face challenges related to weight, excrescence drag, and noise abatement, necessitating improvements for enhanced efficiency and performance.
Innovation Solution
The design incorporates a thrust reverser assembly with blocker doors that pivot radially inward and are coupled to a translating sleeve via pivot joints, featuring a blocker door brake and drag linkage, which allows for deployment and stowage within an annular bypass duct, eliminating the need for cascade sets and utilizing an outer wall for noise abatement, reducing drag and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bypass duct thrust reversers are used, then thrust reversal functionality is achieved, but weight and excrescence drag increase
Solution Approach 1:
The thrust reverser system is divided into multiple independent blocker doors (first blocker door, second blocker door, third blocker door, fourth blocker door) that can be independently controlled and deployed. Each blocker door is connected to the translating sleeve through separate drag linkages and pivot joints, allowing segmented deployment and reducing the weight of any single moving component while maintaining overall functionality.
Solution Approach 2:
The blocker doors are designed with dynamic deployment capability through pivot joints (first pivot joint, second pivot joint) that allow the doors to rotate from a retracted position to a deployed position. The drag linkages connect the translating sleeve to each blocker door, enabling dynamic adjustment of door positions based on the translating sleeve's movement, thus reducing weight while maintaining thrust reversal functionality.
2Reliability
If traditional bypass duct thrust reversers are used, then thrust reversal functionality is achieved, but excrescence drag increases
Solution Approach 1:
The cascade sets traditionally used in bypass duct thrust reversers are completely eliminated from the design. Instead, the blocker doors directly interface with the bypass duct airflow without requiring intermediate cascade structures. This extraction of unnecessary components reduces excrescence drag while maintaining the ability to reverse thrust effectively.
Solution Approach 2:
The blocker doors are positioned at different angular orientations relative to the bypass duct airflow. The first and second blocker doors are oriented at different angles than the third and fourth blocker doors, creating a multi-dimensional flow control approach that reduces drag by optimizing the interaction between each door and the airflow in different spatial dimensions.
3Weight of moving object
If lighter thrust reverser components are used, then weight is reduced, but strength and robustness may be compromised
Solution Approach 1:
The blocker doors are designed to utilize composite material construction, combining lightweight materials with high strength-to-weight ratio. The doors incorporate reinforced structures at critical stress points while maintaining overall lightweight design, allowing weight reduction without compromising the strength and robustness required for withstanding engine exhaust forces and airflow pressures.
Solution Approach 2:
The blocker doors are equipped with brakes (first blocker door brake, second blocker door brake) that can be engaged before deployment to prevent unintended movement. This preliminary action ensures that the lighter blocker doors remain stationary and secure during normal operation, maintaining system robustness while allowing weight reduction for the moving components.
4Reliability
If blocker doors are deployed into bypass air stream, then thrust reversal is achieved, but drag increases
Solution Approach 1:
The blocker doors are designed with dynamic deployment capability through pivot joints that allow the doors to rotate from a retracted position (parallel to airflow) to a deployed position (perpendicular to airflow). The drag linkages connect the translating sleeve to each blocker door, enabling dynamic adjustment of door positions based on the translating sleeve's movement, thus reducing drag during cruise while maintaining thrust reversal functionality when needed.
Solution Approach 2:
The thrust reversal function is divided among multiple blocker doors that can be independently deployed and retracted. This segmentation allows selective deployment of only the necessary number of doors based on thrust reversal requirements, minimizing the total drag penalty compared to deploying a single large door or all doors simultaneously, while still achieving effective thrust reversal.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A thrust reverser (28) is adapted to be fixed within a turbofan engine nacelle (14) that extends substantially about an engine core cowl (18). The nacelle and engine core cowl together define an axially extending bypass duct (22) for receiving an aft flowing fan bypass air stream that is forwardly redirected upon deployment of the thrust reverser. The nacelle includes an axially translating sleeve (16), circumferentially arranged translating cascade sets (20), and axially translatable blocker doors (40) adapted to pivot radially inwardly from the translating sleeve to extend at least partially into the fan bypass air stream. A blocker door deployment drag linkage (42) is pivotally coupled to each of the translating sleeve and the blocker doors. When stowed, an axially extending outer wall (50) of the bypass duct is radially interposed between each blocker door and the fan bypass air stream to assure that the blocker doors remain entirely concealed from the fan bypass air stream.