Turbofan Engine Mounting Assembly Load Distribution
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Solution Overview
Problem
The existing mounting systems for turbofan engines to pylons lead to increased internal stresses in outlet guide vanes due to pitch moments, resulting in oversized vanes that increase weight and cost, and rotational deflection between the fan and core cases, which can reduce engine performance.
Innovation Solution
A mounting assembly with multiple independent mounts, including a first mount for axial thrust transfer and a second mount for radial, lateral, and torsional load transfer, configured to reduce pitch moments on vanes and allow for modular support of the fan and core cases, enabling independent installation and servicing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single forward mount is used to connect the fan case to the pylon, then the mounting structure is simple, but the outlet guide vanes experience increased pitch moments and internal stresses
Solution Approach 1:
The mounting system is divided into multiple independent mounts: a first mount connecting the fan case to the pylon, and a second mount connecting the core case to the pylon. This segmentation distributes the loads away from the outlet guide vanes, reducing pitch moments and internal stresses while maintaining structural simplicity through modular design.
2Strength
If the outlet guide vanes are oversized to compensate for increased internal stresses, then the vanes can withstand the stresses, but the overall weight and cost of the turbofan engine increase
Solution Approach 1:
The harmful pitch moment loads are extracted from the outlet guide vanes by introducing a second mount that independently supports the core case. This removes the excessive loading from the vanes, allowing them to be sized appropriately for their actual functional requirements rather than being oversized to compensate for mounting-induced stresses.
3Strength
If the radial heights of the outlet guide vanes are increased to compensate for internal stresses, then the vanes can handle the loads, but vane flexibility increases and rotational deflection occurs between the fan case and core case
Solution Approach 1:
By segmenting the mounting system into independent first and second mounts, the structural connection between the fan case and core case is reduced. This allows each case to be supported independently, minimizing rotational deflection and maintaining stability without requiring increased vane height.
4Device complexity
If a single mount is used for both fan case and core case, then the mounting assembly is simple, but the fan section and core case cannot be independently installed or serviced
Solution Approach 1:
The mounting assembly is segmented into a first mount for the fan case and a second mount for the core case, enabling independent installation and maintenance of each section. This modular approach adds minimal complexity while dramatically improving ease of repair and servicing.
Data Source
AI summary
An assembly is provided for mounting a turbofan engine to a pylon. The turbofan engine includes a fan section and an engine core. The mounting assembly includes a fan case, a first mount and a second mount. The fan case is configured to house the fan section of the turbofan engine. The first mount is connected to the fan case, and configured to mount the fan case to the pylon. The second mount is connected to the fan case, and configured to mount the fan case to the pylon.