Variable Area Fan Nozzle Actuator Nesting
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Solution Overview
Problem
Gas turbine engines with variable area fan nozzles face limitations in packaging a large fan due to the need for actuators, which restrict the size of the fan that can be installed on pre-existing aircraft, and low pressure ratio fans are susceptible to stability/flutter issues at low flight speeds.
Innovation Solution
A nacelle assembly with a variable area fan nozzle (VAFN) that adjusts the fan nozzle exit area using a movable second fan nacelle section and actuator assembly, allowing for selective variation of the bypass flow path to manage fan operability and stability across different flight conditions without affecting the fan section's incidence angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a VAFN is utilized to manage fan operability, then fan stability is improved, but device complexity increases due to actuators
Solution Approach 1:
The actuator assembly is nested within the movable fan nacelle section, with the actuator housed inside the nacelle section cavity. This integration eliminates the need for external actuator mounting structures and reduces overall device complexity while maintaining the VAFN stability benefits.
Solution Approach 2:
The movable fan nacelle section combines multiple functions: it serves as both the nozzle area adjustment mechanism and the housing for the actuator assembly. This merging of functions reduces the total number of components and simplifies the overall system architecture.
2Use of energy by moving object
If a larger fan is installed to maximize fuel burn benefit, then fuel efficiency is improved, but device complexity increases due to actuator requirements
Solution Approach 1:
The actuator assembly is nested within the movable fan nacelle section, eliminating the need for external actuator mounting structures. This integration is particularly beneficial for larger fan installations where external actuators would significantly increase nacelle complexity and packaging difficulties.
Solution Approach 2:
The fan nacelle is segmented into fixed and movable sections, with the actuator assembly integrated into the movable section. This segmentation allows the large fan to be controlled in a manageable way, reducing overall system complexity while maintaining fuel efficiency benefits.
3Reliability
If the fan nozzle exit area is varied to manage fan operability, then fan stability is improved, but device complexity increases
Solution Approach 1:
The movable fan nacelle section merges the nozzle area adjustment function with the actuator housing function. This single component performs multiple tasks, reducing device complexity while maintaining reliable fan operability across different flight conditions.
Solution Approach 2:
The actuator is nested within the movable nacelle section, creating a compact integrated assembly. This nesting approach reduces the number of separate components and simplifies the control system while ensuring reliable fan operability through precise area adjustment.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A nacelle assembly for a high-bypass gas turbine engine (10) includes a variable area fan nozzle (42) in communication with a fan bypass flow path (40). An actuator assembly (56) is operable to move a second fan nacelle section (54) relative to a first fan nacelle section (52) to vary a fan nozzle exit area and adjust fan bypass airflow. The actuator assembly (56) extends at least partially into the fan bypass flow path (40).