Compressor Housing Ferrule Segmentation for Turbine Engine Stress
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Solution Overview
Problem
In axial turbomachines, particularly in compressors, the shroud experiences stress concentration zones due to axial forces and torque transmission, leading to mechanical strength challenges and weight issues, which existing solutions address by increasing thickness or adding reinforcing parts.
Innovation Solution
A compressor casing design featuring a shell with upstream and downstream ferrules, each attached only at their proximal end, creating an axial clearance to prevent force transmission between them, allowing the casing to absorb airflow and vane-induced forces independently, thereby reducing mechanical stress and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the shroud thickness is increased or reinforcing parts are added to ensure mechanical strength in stress concentration zones, then the mechanical strength is improved, but the weight of the compressor and turbomachine increases
Solution Approach 1:
The shroud is segmented into multiple independent ferrules (upstream ferrule, downstream ferrule, intermediate ferrules) that are fixed to the shell at discrete locations rather than forming a continuous structure. This segmentation allows each ferrule to independently support stator vanes and transmit forces to the shell, eliminating the need for a thick continuous shroud while maintaining mechanical strength.
2Force
If the shroud is designed as a continuous structure to transmit axial forces and torque, then the force transmission capability is improved, but the stress concentration zones increase and require additional weight for reinforcement
Solution Approach 1:
The shell acts as an intermediary structure that receives forces from multiple discrete ferrules at different locations. Instead of forces being concentrated at single attachment points in a continuous shroud, the shell distributes and manages these forces across its structure, reducing stress concentrations while maintaining force transmission capability.
3Stability of the object's composition
If the ferrules are rigidly connected to each other to maintain structural integrity, then the structural stability is improved, but the force transmission from one ferrule to another increases stress concentrations
Solution Approach 1:
The ferrules are made independent and non-connected, with each ferrule fixed to the shell at its own location. This segmentation prevents force transmission between ferrules, eliminating stress concentration zones at ferrule-to-ferrule junctions while maintaining structural stability through direct ferrule-to-shell connections.
4Ease of manufacture
If the shroud is made as a single integrated component to simplify manufacturing, then the manufacturing process is simplified, but the maintenance complexity increases due to inability to replace individual parts
Solution Approach 1:
The shroud is divided into multiple separable ferrules that can be independently manufactured and assembled to the shell. This segmentation enables individual ferrules to be replaced during maintenance without replacing the entire shroud structure, improving ease of repair while maintaining manufacturing simplicity through modular construction.
Data Source
AI summary
A compressor casing for a turbine engine, the casing comprising: a housing comprising a radially inner e surface; an upstream ferrule; and a downstream ferrule; each of the ferrules having a respective inner surface capable of defining an air stream, and each of the ferrules having an outer surface facing the inner surface of the housing, the ferrules being attached to the cantilevered housing and being axially arranged so as to be separated by an axial clearance. Additionally, a turbine engine comprising such a casing and a stage of variable-setting vanes.