Aft-Mounted Pusher Fan Layout for Geared Turbine Packaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Historically, gas turbine engines face packaging challenges due to the increased outer diameter of the fan rotor resulting from gear reduction, which is incorporated to allow the fan to rotate slower than the fan drive turbine, leading to inefficiencies and mount location issues, particularly in aircraft applications.
Innovation Solution
The fan is relocated to an aft position within the engine, with a gear reduction system positioned aft of the fan drive shaft, incorporating flexible couplings, oil seals, and bearings to efficiently package complex structures, allowing for a compact design that supports the fan hub and blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If gear reduction is incorporated to allow the fan to rotate slower than the fan drive turbine, then fan efficiency is improved, but the outer diameter of the fan rotor increases causing packaging challenges
Solution Approach 1:
The patent repositions the fan from a forward-mounted configuration to an aft-mounted configuration, effectively changing the spatial dimension and arrangement of components. This allows the fan drive shaft to extend aftward through the core engine rather than being constrained within the forward section, enabling a larger fan diameter without increasing the overall engine footprint in critical dimensions.
Solution Approach 2:
Instead of mounting the fan at the forward end of the engine (conventional arrangement), the patent inverts the mounting location to the aft end. This inversion allows the fan drive shaft to pass through the core engine structure, accommodating the larger fan diameter required for gear reduction while maintaining compact packaging.
2Speed
If gear reduction is incorporated between the low pressure compressor and the fan rotor, then the fan rotor can rotate slower for efficiency, but packaging challenges arise with mount locations
Solution Approach 1:
The patent nests the fan drive shaft within the core engine structure, with the shaft passing through the turbine section and being supported by bearings integrated into the engine architecture. This nesting approach accommodates the additional components required for gear reduction without significantly increasing external dimensions or mounting complexity.
Data Source
AI summary
A fan drive turbine drives a drive shaft. A compressor section and a turbine section rotate about a rotational axis, with the turbine section positioned in a downstream direction. A fan has fan blades and a fan hub positioned radially within a fan case, with the fan case defining a bypass duct. A fan inlet guide vane case is upstream of the fan blades and a fan exit guide vane case is mounted downstream. The drive shaft is mounted on at least one input drive shaft bearing inwardly of the fan inlet guide vane case. The drive shaft drives a flexible coupling to in turn drive a gear reduction. The gear reduction drives a fan drive shaft to in turn drive the fan hub. At least two fan drive shaft bearings support the fan drive shaft within the fan exit guide vane case. An aircraft is also disclosed.