Aircraft Thrust Reverser Cascade Boxes with Varying Vane Angles
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Solution Overview
Problem
Thrust reverser systems in aircraft propulsion face challenges in producing sufficient reverse thrust while minimizing bypass airflow reingestion, especially at low airspeeds, which limits their effectiveness and requires disengagement at speeds above 60 knots, necessitating reliance on landing gear braking.
Innovation Solution
The design incorporates cascade boxes with varying forward and side turning angles, allowing for redirecting bypass airflow to minimize reingestion and enhance reverse thrust production, including the use of negative forward turning angles and progressive angle changes across ladders within the cascade boxes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If cascade vanes have substantial forward turning angles to create reverse thrust, then reverse thrust effectiveness is improved, but the available reverse thrust area is pinched and cascade box length must be increased, resulting in increased weight
Solution Approach 1:
The cascade vanes are designed with varying forward turning angles within different ladders rather than uniform angles throughout. This local variation optimizes reverse thrust generation in specific areas while maintaining adequate flow area in other regions, eliminating the need for increased cascade box length and associated weight penalty
Solution Approach 2:
The invention changes the parameter of forward turning angle across different ladders of the cascade box. By adjusting this parameter locally rather than uniformly, the system achieves effective reverse thrust without pinching the available flow area, thus avoiding the need for longer cascade boxes and reduced weight
2Force
If the thrust reverser system is deployed to produce reverse thrust, then braking force is improved, but bypass air reingestion increases causing pressure and temperature distortion within the gas turbine engine
Solution Approach 1:
Different ladders within the cascade box are assigned different forward turning angles based on their local position and flow characteristics. This local differentiation allows the system to direct bypass air away from the engine inlet in critical areas while maintaining reverse thrust effectiveness, thereby reducing reingestion without sacrificing braking force
Solution Approach 2:
The cascade box with its specifically configured vanes acts as an intermediary device that mediates between the bypass airflow and the engine inlet. By controlling the flow direction through strategically angled vanes, it redirects bypass air away from the engine while still producing the necessary reverse thrust, preventing harmful reingestion
3Speed
If the cutoff speed is reduced to extend thrust reverser usage at lower speeds, then braking effectiveness at low speed is improved, but bypass air reingestion increases making the system unreliable
Solution Approach 1:
The differentiated vane angles across ladders create localized flow control that maintains reliable operation at lower speeds by preventing reingestion even when the aircraft is moving slowly. This local optimization ensures that the system remains reliable below traditional 60-knot cutoff speeds
Solution Approach 2:
The cascade box design dynamically adapts to different operating conditions including low speeds. The specific vane angle configuration ensures that at low aircraft speeds, the bypass air is effectively redirected away from the engine inlet, maintaining system reliability and allowing extended use below traditional cutoff speeds
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 decreases the potential for thrust reverser air reingestion, increases reverse thrust effectiveness, and allows for lower cutoff speeds, reducing the burden on landing gear and enabling aircraft backup without external assistance.
Implementation Method 1
each cascade box includes a plurality of forward turning vanes and side turning vanes, each configured with a different forward turning angle and side turning angle, respectively
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A cascade box is provided that includes a plurality of lengthwise extending side turning vanes and a plurality of forward turning vanes. Each of the plurality of lengthwise extending side turning vanes is configured to have a side turning angle. Each of the plurality of forward turning vanes is attached to respective adjacent ones of the plurality of side turning vanes, and each forward turning vane is configured to have a forward turning angle, and at least one of the forward turning vanes is configured to have a negative forward turning angle.