Turbofan Mounting Rod Frame for Core Distortion Control
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Solution Overview
Problem
Traditional turbofan gas turbine engine mounting systems suffer from distortion and bending due to inertia and thrust loads, leading to tip clearance loss and reduced efficiency in axial compressors.
Innovation Solution
A mounting system with a front and rear structure, utilizing three pairs of tangentially extending rods that interconnect the bypass duct wall and the core portion, forming a short circuit to transfer inertia-induced loads and reduce distortion and bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cantilever core mounting system is used, then the structure is simple, but the core portion distorts due to inertia loads causing tip clearance loss
Solution Approach 1:
The mounting system is segmented into multiple discrete rod elements (three pairs of rods) that connect the core portion to the bypass duct wall. This segmentation allows each rod to independently carry specific loads and provides flexibility in distributing inertia loads, thereby reducing core distortion while maintaining structural simplicity.
Solution Approach 2:
The mounting system transitions from a planar cantilever structure to a three-dimensional spatial framework using rods extending in multiple directions (radially, tangentially, and axially). This dimensional change creates a more rigid load-bearing structure that resists core distortion under inertia loads while preserving tip clearance.
2Device complexity
If a rear core mount is used, then the mounting structure is simplified, but the core portion experiences significant bending due to thrust loads
Solution Approach 1:
The rod frame structure provides localized support at specific positions around the core portion (three pairs of rods circumferentially distributed). This local reinforcement strategically addresses thrust load-induced bending without requiring a complete restructuring of the entire mounting system, thus simplifying the overall structure while maintaining core shape stability.
Solution Approach 2:
The mounting system merges multiple functions into a single integrated rod frame structure: supporting the core portion, resisting thrust loads, and preventing bending. This consolidation of functions reduces the number of separate mounting components needed while effectively controlling core portion shape under various loading conditions.
3Ease of manufacture
If traditional mounting systems are used, then the design is conventional, but the core portion experiences distortion and bending leading to reduced compressor efficiency
Solution Approach 1:
The rod frame structure acts as an intermediary element between the core portion and the bypass duct wall, mediating the transmission of loads. This intermediary structure isolates the core portion from direct exposure to inertial and thrust loads, preventing distortion and bending that would otherwise reduce compressor efficiency, while maintaining a manufacturable design.
4Device complexity
If the thrust line is offset from the thrust reaction plane, then the mounting arrangement is simplified, but the rear mount carries additional moment loads causing carcass bending
Solution Approach 1:
The rod frame structure is pre-configured to counteract the moment loads generated by the offset thrust line. By establishing this rigid triangular framework before operation, the system proactively resists carcass bending under moment loads, preventing strength degradation without complicating the mounting arrangement.
Data Source
AI summary
A gas turbine engine has a rear mounting structure incorporating a mounting apparatus attached to a bypass duct wall with a link device of six rods for transferring core portion related inertia-induced loads, from an inner case of the core portion in a short circuit across an annular bypass air passage to the bypass duct wall.