Variable Pitch Fan Actuator External Placement
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Solution Overview
Problem
The existing actuation systems for variable pitch fans in gas turbine engines are complex and difficult to maintain due to the placement of actuators within the core air flowpath, requiring pressurized hydraulic fluid transfer from a static to a rotating frame of reference, which complicates repairs and maintenance.
Innovation Solution
An actuation device with an actuator located outward of the core air flowpath, connected to the fan blades through a connection assembly that includes a rotating to static transfer device, allowing for easier access and maintenance, and eliminating the need for hydraulic fluid transfer across the rotating frame of reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the actuator is packaged within the fan section proximate to the fan blades, then the actuation system can directly control blade pitch, but the actuator becomes difficult to repair and maintain
Solution Approach 1:
The actuation system is divided into separate components: the actuator is positioned outside the fan section while the control mechanism remains with the fan blades. This segmentation allows the actuator to be easily accessed for maintenance while still effectively controlling blade pitch through a connection assembly that extends through the core air flowpath.
2Ease of operation
If the actuator is located within the fan section, then direct blade actuation is achieved, but the engine complexity increases due to hydraulic fluid transfer requirements
Solution Approach 1:
The actuator is extracted from the fan section and repositioned outside the core air flowpath. This eliminates the need for complex hydraulic fluid transfer mechanisms between rotating and static frames of reference, while the connection assembly maintains the necessary actuation function through a simpler mechanical linkage.
3Ease of repair
If the actuator is positioned outward of the core air flowpath, then maintenance accessibility is improved, but the connection to fan blades becomes more complex
Solution Approach 1:
A connection assembly serves as an intermediary element between the externally positioned actuator and the fan blades. This connection assembly extends through the core air flowpath and provides the necessary mechanical linkage, allowing the actuator to be easily accessed while maintaining effective blade control.
Data Source
AI summary
A gas turbine engine including a core having in serial flow order a compressor, a combustor, and a turbine—the compressor, combustor, and turbine together defining a core air flowpath. The gas turbine engine additionally includes a fan section mechanically coupled to the core, the fan section including a plurality of fan blades, and each of the plurality fan blades defining a pitch axis. An actuation device is operable with the plurality fan blades for rotating the plurality fan blades about their respective pitch axes, the actuation device including an actuator located outward of the core air flowpath to, e.g., simplify the gas turbine engine.