Composite Compressor Casing With Decoupled Axial Force Interface
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Solution Overview
Problem
Existing turbomachine compressor designs face issues with stress concentration and weight due to axial forces and torque transmission, often requiring additional thickness or reinforcements, which complicate assembly and increase weight.
Innovation Solution
A compressor casing design using a composite material ferrule with angular platforms and abradable material rings that decouple axial forces, eliminating stress concentration and reducing weight by avoiding welds and incorporating deformable rings for thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If axial force is transmitted between platforms and ring, then structural stability is improved, but clearances between rotor and stator blades deteriorate due to relative movement
Solution Approach 1:
A flexible membrane is introduced as an intermediary element between the platforms and the ring. The membrane transmits axial forces from the rotor to the stator assembly while its flexible nature allows it to accommodate relative movements without transmitting them to the blade clearances. This mediator absorbs the incompatibility between force transmission requirements and clearance maintenance.
Solution Approach 2:
The stator assembly is segmented into multiple platforms that can move independently axially relative to each other. Each platform is supported by individual flexible membranes, allowing localized adjustment and movement accommodation. This segmentation enables the structure to maintain overall stability while allowing local flexibility to preserve blade clearances.
2Weight of moving object
If composite material is used for outer shell, then weight is reduced, but manufacturing complexity increases
Solution Approach 1:
The composite outer shell is divided into multiple angular segments that can be manufactured separately and assembled together. This segmentation reduces the manufacturing complexity of each individual composite piece while maintaining the overall weight benefits of composite material usage. The segmented design also facilitates installation and maintenance.
3Manufacturing precision
If abradable material layer is added to ring, then clearance control is improved, but device complexity increases
Solution Approach 1:
The abradable material layer is designed as a consumable element that gradually wears during operation to maintain optimal clearances. Rather than designing a complex adjustable mechanism, a relatively simple ring structure with a sacrificial abradable coating is used. This disposable layer simplifies the overall device complexity while providing excellent clearance control throughout the engine life.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves lighter weight and improved mechanical strength by decoupling axial forces, allowing for thermal expansion without stress concentration and enabling easier maintenance of abradable material layers.
Implementation Method 1
The interface between the platforms and the ring is such that no axial force is transmitted between these elements
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Compressor casing (34) for a turbomachine, particularly for an aircraft turbojet engine, the casing (34) comprising: an outer shell (35) made of composite material and optionally formed of several angular shell segments; an annular row of platforms (42) fixed to the shell (35), each platform (42) supporting one or more stator blades (32); and a ring (46), optionally formed of several angular ring segments, and having a layer of abradable material (44). The interface between the platforms and the ring is such that no axial force is transmitted between these elements.