Sectorized Fixed Rectifier Stresses in Turbomachine Compressor
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Solution Overview
Problem
The existing sectorized fixed rectifiers for turbomachine compressors face stress-related deterioration or destruction at the leading and trailing edges due to inadequate support from the outer shroud, leading to reduced assembly life.
Innovation Solution
A set of sectorized fixed rectifiers with two coaxial shrouds and radial blades, where the leading and trailing edges are connected to less rigid areas of the outer shroud, allowing better force distribution and stress absorption, with flexible rims and varying thicknesses to optimize stress transmission and natural frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the leading and trailing edges of the blades are connected to thick and rigid parts of the shroud, then the structural strength is improved, but the stresses are not properly damped and lead to deterioration or destruction of the blade edges
Solution Approach 1:
The shroud is designed with non-uniform thickness: thick and rigid portions at the axial ends for mounting tabs, and thin and flexible portions at the radial ends for blade connections. This local variation in structural properties allows the shroud to provide both overall structural strength and local stress damping where needed.
Solution Approach 2:
The thickness parameter of the shroud is varied along its length to achieve different mechanical properties in different zones. The shroud transitions from thick (rigid) at the axial ends to thin (flexible) at the radial ends, changing the structural parameter to optimize both strength and stress absorption.
2Stability of the object's composition
If the shroud is made thick and rigid to support mounting tabs, then the mounting stability is improved, but the blade edge stresses are not damped leading to reduced assembly life
Solution Approach 1:
The shroud exhibits local quality variations with thick rigid sections at axial ends for stable mounting and thin flexible sections at radial ends for stress damping, thereby maintaining both mounting stability and extended assembly life.
Solution Approach 2:
The shroud is effectively segmented into different functional zones: axial end regions for mounting with different mechanical properties than radial end regions for blade connection, allowing each zone to optimize its specific function.
3Length of moving object
If a one-piece casting is used for the rectifier assembly, then the axial footprint is reduced, but the blade edges lack sufficient stress damping from the shroud
Solution Approach 1:
The one-piece casting incorporates local quality variations with thin flexible portions of the shroud at the blade connection zones, providing necessary stress damping while maintaining the compact axial footprint of an integrated design.
Solution Approach 2:
The rectifier assembly merges the shroud and blades into a single integrated casting, combining the advantages of compact axial footprint with the functional benefits of differentiated shroud thickness zones for stress management.
Data Source
Figure 1~2
Figure 3~5
AI summary
A sectorized fixed rectifier assembly (50) for a turbomachine compressor, this assembly being made of a single piece and comprising two coaxial ferrules (20, 52) connected by radial blades (24), the outer ferrule comprising two annular lugs (56, 66) for mounting on a compressor housing, at least one of these annular lugs being connected to the outer ferrule in an area axially spaced from the area of connection of the leading edges (26) or trailing edges (28) of the blades to the outer ferrule.