Lattice Fan Duct Casing for Turbomachine Maintenance Access
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Solution Overview
Problem
The existing fan ducts in turbo-jet engines, particularly those attached to aircraft, pose difficulties in maintenance due to their solid cylindrical shape, which restricts access to the engine, leading to prolonged downtime and structural distortion issues.
Innovation Solution
A fan duct design featuring a lattice framework with removable cowling panels that separates structural and aerodynamic components, allowing easy access and improved force transmission, while maintaining rigidity and reducing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the external wall of the duct is made as a one-piece solid cylindrical structure, then the structural strength and rigidity are improved, but the accessibility for maintenance operations deteriorates
Solution Approach 1:
The external wall of the duct is segmented into a solid support structure and removable access panels. The support structure maintains structural integrity while the access panels can be removed to provide maintenance access to the engine and nozzles. This segmentation resolves the contradiction by separating the structural function from the access function.
Solution Approach 2:
Access panels are extracted as separate removable components from the solid cylindrical structure. These panels can be taken out independently to allow maintenance operations without compromising the overall structural strength of the duct when the panels are in place.
2Ease of operation
If access traps are created in the solid cylindrical structure, then the accessibility for maintenance is improved, but the structural strength and rigidity deteriorate
Solution Approach 1:
Instead of creating access traps in the solid structure, the duct is segmented into a solid support framework and separate access panels. The panels are positioned to provide access while the solid framework between them maintains structural strength.
3Ease of operation
If the duct structure is made more open for maintenance access, then the accessibility is improved, but the rigidity and force transmission capability deteriorate
Solution Approach 1:
The duct is segmented into a rigid support structure and removable panels. The support structure maintains rigidity and force transmission capability, while the panels provide access when removed. This segmentation allows the structure to be open for maintenance without compromising overall rigidity.
Solution Approach 2:
The access panels are extracted as separate components that can be removed for maintenance. When removed, they provide access without requiring the entire structure to be opened, thus maintaining the rigidity of the remaining support structure.
4Force
If the solid cylindrical structure is used, then the force transmission is improved, but the maintenance duration increases
Solution Approach 1:
The duct is segmented into a solid support structure for force transmission and removable access panels for maintenance. This allows maintenance personnel to quickly remove panels and access engine components without having to dismantle the entire structure, reducing maintenance duration while preserving force transmission capability.
Solution Approach 2:
Access panels are extracted as separate removable components that can be quickly taken out for maintenance operations. This extraction allows maintenance personnel to access engine components rapidly without compromising the solid structure's ability to transmit forces when the panels are in place.
Data Source
AI summary
Twin-flow turbo-jet engine, comprising a cylindrical casing externally defining an annular flow space for a secondary flow, wherein the cylindrical casing is formed from a lattice framework and from removable cowling panels fixed to the framework, said framework comprising an upstream annular flange for fixing to an intermediate housing, a downstream annular flange for connecting to an exhaust housing and rigid beams parallel or inclined relative to the axis of the turbo-jet engine, connecting the two flanges to one another.