Variable Area Fan Nozzle Louver System for Gas Turbine Efficiency
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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 fan variable area nozzles are heavy due to complex mechanisms, negating increased fuel efficiency.
Innovation Solution
A lightweight, movable louver system with adjustable slats in the fan nozzle exit area that responds to pressure ratios during different flight conditions, allowing for symmetrical or asymmetrical variation of the fan nozzle exit area to optimize thrust efficiency and fuel economy.
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 implementing a movable louver system that can change the fan nozzle exit area from a fixed geometry. The louvers are actuated to vary the nozzle area dynamically, allowing the engine to optimize performance for different flight conditions (take-off, cruise, landing) rather than being constrained to a single fixed geometry configuration
2Productivity
If an existing fan variable area nozzle is used, then the engine efficiency is improved for different flight conditions, but the overall engine weight increases due to complex mechanisms
Solution Approach 1:
The patent applies segmentation by dividing the nozzle control into multiple independent louver elements rather than using a single complex mechanism. Each louver can be actuated independently or in groups, allowing the system to achieve variable area functionality through simpler, distributed components that reduce overall mechanism weight and complexity
Solution Approach 2:
The patent replaces traditional complex mechanical variable area nozzle mechanisms with a louver system that can be actuated by simpler means (such as pneumatic or electric actuators). This substitution reduces the mechanical complexity and weight while maintaining the ability to vary the nozzle exit area for different flight conditions
Data Source
Figure 1
Figure 2~3B
AI summary
A turbofan engine includes a fan variable area nozzle, which includes a louver system having a multiple of slats generally transverse to the engine axis. Each of the louver slats are pivotally mounted to the fan nacelle to vary the effective area of the fan nozzle exit area and permit efficient engine operation at predefined pressure ratios.