Variable Area Fan Nozzle Asymmetry for Thrust Vectoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gas turbine engines with fixed geometry fan nozzles are inefficient as they compromise between take-off and cruise conditions, and existing variable area nozzles are heavy, negating fuel efficiency gains.
Innovation Solution
A lightweight fan variable area nozzle system that adjusts the entire periphery of the fan nozzle exit area by moving sectors of the second fan nacelle section, allowing for symmetrical and asymmetrical changes to optimize thrust and fuel economy across flight regimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed geometry fan nozzle is used, then the engine structure is simple and lightweight, but the engine efficiency is compromised between take-off and cruise conditions
Solution Approach 1:
The patent applies the dynamics principle by making the fan nozzle geometry variable instead of fixed. The nozzle includes movable sections (such as the afterbody section and chevrons) that can be adjusted to different positions to optimize performance for different flight conditions. This allows the nozzle to dynamically adapt its shape, providing improved engine efficiency for both take-off and cruise conditions while maintaining a relatively simple overall structure.
2Productivity
If an existing fan variable area nozzle is implemented, then the engine efficiency is improved for different flight regimes, but the overall engine weight increases significantly
Solution Approach 1:
The patent applies segmentation by dividing the fan nozzle into distinct movable sections, particularly the afterbody section and chevrons, which can be independently adjusted. This segmentation allows for optimized performance across different flight regimes without requiring a complete redesign of the entire nozzle system, thereby controlling weight increase while achieving improved fuel efficiency.
Solution Approach 2:
The patent applies local quality by making specific portions of the nozzle (the afterbody and chevrons) variable rather than the entire nozzle structure. This localized variability provides the necessary adaptability for different flight conditions while minimizing the overall weight penalty associated with variable geometry systems.
3Productivity
If the fan nozzle exit area is varied symmetrically, then thrust and fuel economy are maximized, but maneuvering capability is limited
Solution Approach 1:
The patent applies asymmetry by allowing the movable nozzle sections (afterbody and chevrons) to be positioned asymmetrically relative to each other. This asymmetric positioning capability enables bypass flow vectoring, which provides trim balance, thrust controlled maneuvering, and enhanced ground operations while maintaining the ability to operate symmetrically for optimized fuel economy during steady flight conditions.
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A turbofan engine includes a fan variable area nozzle having an axial overlapped nozzle assembly with a first fan nacelle section and a second fan nacelle section movably mounted relative the first fan nacelle section. The second fan nacelle section axially slides forward along the engine axis relative the fixed first fan nacelle section to change the effective area of the fan nozzle exit area.