Turbojet Inter-Compressor Case Axial Stress Rods
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Solution Overview
Problem
In traditional turbojet engines, the low mechanical strength of the LP compressor case leads to deformations and efficiency losses due to axial stress transmission, which is exacerbated by the need for ultra-high bypass ratios and the presence of a reduction gear, causing increased weight and potential stator/rotor contact risks.
Innovation Solution
A multi-flow turbojet engine design featuring axial stress transmission rods connecting the inlet case to the inter-compressor case in a V-shape configuration, allowing for a more rigid stress path that reduces the load on the compressor case, with ball-type connections to transmit only tensile/compression stresses, and adjustable rod lengths to manage stress distribution effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the LP compressor case is used to transmit axial stress, then the thrust take-up function is achieved, but the low mechanical strength of the LP compressor case leads to deformations and efficiency losses
Solution Approach 1:
The patent introduces a dedicated stress transmission rod as an intermediary element between the LP compressor case and the thrust take-up rod. This rod acts as a mediator that carries the axial stress away from the LP compressor case, preventing the case from bearing the full mechanical load. The rod is specifically positioned to receive stress from the LP compressor case and transmit it to the thrust take-up rod, thereby protecting the weaker LP compressor case from deformation while maintaining effective thrust transmission.
2Strength
If the LP compressor case is reinforced to increase mechanical strength, then deformation resistance improves, but the weight of the engine increases
Solution Approach 1:
Instead of reinforcing the LP compressor case, the patent uses a dedicated stress transmission rod as an intermediary structure. This rod is specifically designed to handle the axial stress loads, allowing the LP compressor case to remain lightweight while still achieving the required mechanical strength for thrust transmission. The rod transfers the load path from the case to a dedicated structural element.
3Manufacturing precision
If the LP compressor case is reinforced to prevent deformations, then manufacturing precision is maintained, but the device complexity increases
Solution Approach 1:
The patent introduces a dedicated stress transmission rod as an intermediary element that specifically addresses the precision problem. By transferring the stress load to this dedicated rod, the LP compressor case is relieved of deformation stresses that would otherwise affect blade clearances. This approach maintains manufacturing precision without requiring complex reinforcement structures, as the rod provides a simple, dedicated load path.
Data Source
AI summary
A multi-flow turbojet engine generally includes an upstream ducted fan driven by a gas generator, the gas generator having a first and a second compressor, which are coaxial, an inlet case forming a support for the rotors of the upstream ducted fan and of the first compressor, an inter-compressor case downstream of the inlet casing and forming a support for the rotors of the second compressor, attachment means for thrust take-up rods, which attachment means are arranged on the inter-compressor case. The turbojet engine includes at least one axial stress transmission rod for connecting the inlet case to the inter-compressor case.