Translatable Cascade Thrust Reverser Nacelle Assembly
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Solution Overview
Problem
High-bypass gas turbine engines face challenges in thrust reversal due to susceptibility to fan stability/flutter problems at low power and low flight speeds, and existing thrust reverser systems are inefficient in terms of length, weight, and drag.
Innovation Solution
A nacelle assembly with a variable area fan nozzle (VAFN) and cascade arrays that adjust the fan nozzle exit area and redirect bypass flow for thrust reversal, using a track and actuator system to vary the fan nozzle exit area and vector bypass flow for improved thrust and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional thrust reverser system with blocking doors and fixed cascade array is used, then thrust reversal function is achieved, but the system increases length, weight, and drag
Solution Approach 1:
The patent combines the translatable sleeve that forms the bypass duct rear wall with the cascade array deflector blades into an integrated thrust reverser system. The cascade array is mounted on the translatable sleeve, allowing both components to move together as a single unit, eliminating the need for separate blocking doors and reducing overall system weight while maintaining thrust reversal functionality.
Solution Approach 2:
The translatable sleeve serves multiple functions: it forms the rear wall of the bypass duct during normal operation, supports the cascade array deflector blades, and provides the structural framework for the thrust reverser mechanism. This multi-functionality reduces the number of separate components needed, thereby reducing weight.
2Reliability
If a traditional thrust reverser system with blocking doors and fixed cascade array is used, then thrust reversal function is achieved, but the system increases length and drag
Solution Approach 1:
The cascade array is integrated onto the translatable sleeve structure, eliminating the need for separate blocking doors and reducing the overall length and diameter of the nacelle assembly. The combined structure allows for a more compact design that achieves thrust reversal without increasing nacelle dimensions.
3Device complexity
If fan nozzle exit area is not variable, then structure is simpler, but thrust efficiency is reduced and fan instability occurs at low power and low flight speeds
Solution Approach 1:
The patent implements a variable area fan nozzle with a translatable sleeve that can adjust the exit area dynamically based on flight conditions. The sleeve translates axially to change the bypass duct cross-sectional area, optimizing fan operation across different power settings and flight speeds, thereby preventing fan instability while maintaining reasonable structural complexity.
4Device complexity
If fan nozzle exit area is not variable, then structure is simpler, but thrust efficiency is reduced
Solution Approach 1:
The variable area fan nozzle allows dynamic adjustment of the bypass duct exit area to optimize thrust efficiency across different operating conditions. The translatable sleeve adjusts the effective area to match demand, improving overall productivity and thrust efficiency while maintaining acceptable structural complexity through the use of a relatively simple translational mechanism.
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 solution enhances thrust reversal efficiency, reduces fan instability, and minimizes drag and weight by optimizing fan operation across flight conditions, improving fuel burn performance and reducing nacelle length and diameter.
Implementation Method 1
the linkages pivot the blocking doors radially inwardly to block the bypass duct and redirect the air flow from the bypass duct through the cascade array in an outwardly and forwardly direction
Implementation Method 2
the translatable sleeve is translated rearwardly to form an outlet defined by a fixed cascade array
Implementation Method 3
the linkages pivot the blocking doors radially inwardly to block the bypass duct
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A nacelle assembly for a high-bypass gas turbine engine (10) includes a fan nacelle (34) that includes a first fan nacelle section (34A) and a second fan nacelle section (34B), the second fan nacelle section (34B) movable relative to the first fan nacelle section (34A). A cascade array (56) is mounted to the first fan nacelle section (34A) for movement relative thereto between a stored position and a deployed position, the stored position locates the cascade array (56) at least partially within the first fan nacelle section (34A).