Aircraft Turbomachine Central Casing Rigidification
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Solution Overview
Problem
The deflection of the central casing in turbomachines leads to increased wear and tear of compressor blades, resulting in higher clearances and reduced efficiency.
Innovation Solution
A dual-flow turbomachine design featuring an intermediate casing with inner and outer ferrules, structural arms, and rigidifying means such as an open-worked annular structure or multiple connecting rods to minimize central casing deflection, including a main case and aerodynamic panels for enhanced mechanical and aerodynamic support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the central casing is made lightweight to reduce overall engine weight, then weight is reduced, but the central casing becomes more prone to deflection under thermal and mechanical loads
Solution Approach 1:
The central casing is divided into multiple segments: the forward casing portion, the intermediate casing with radial supports, and the rear casing portion. This segmentation allows each section to be optimized independently, with the intermediate casing providing structural reinforcement through radial supports while maintaining overall lightweight design
Solution Approach 2:
Radial supports are added in the transverse dimension, extending from the inner ferrule outward to the outer ferrule. These supports create a three-dimensional rigidifying structure that resists deflection without significantly increasing the axial length or overall engine footprint
2Stability of the object's composition
If structural reinforcement is added to the central casing to prevent deflection, then deflection is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The intermediate casing structure serves multiple functions simultaneously: it provides structural reinforcement through radial supports, defines aerodynamic flow paths for secondary air, and creates mounting surfaces for various engine components. This multi-functionality reduces the need for separate reinforcement elements
Solution Approach 2:
The rigidifying structure is nested within the existing casing architecture, with radial supports positioned between the inner and outer ferrules. This nested arrangement provides reinforcement without requiring external additions that would increase complexity
Data Source
AI summary
A turbomachine for an aircraft including a mechanism forming a case fitted in a rear extension of an inner ferrule of an intermediate casing, and positioned around a central casing. The mechanism includes a structural upstream ferrule assembled on the inner ferrule and defining a front portion of a surface internally delimiting a secondary vein, and a main case extending on the upstream ferrule towards the rear. The turbomachine further includes a structural mechanism rigidifying the central casing, surrounded by the case, and extending towards the rear between the upstream ferrule and the central casing on which these mechanisms are assembled.