Turbomachine Rotor Balancing Flange Stress Reduction
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Solution Overview
Problem
Existing turbomachine rotor balancing systems face high tangential stresses at the radial summit of the balancing flange, leading to a short service life and increased risk of deterioration due to the design constraints imposed by the need for screws to press against both tangential ends of the passageway, which limits design freedom.
Innovation Solution
The system employs a balancing flange with through-passageways where each screw/nut assembly has one screw pressing against the first tangential end side of one passageway and another screw pressing against the second tangential end side of a consecutive passageway, allowing for offset tangential attachment without requiring passageways of equal width to the screw diameter, thus reducing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the through-passageway width is dimensioned to allow screws to press against both tangential end sides, then the balance weight is held securely in the tangential direction, but the radial end portion of the passageway remains under great tangential stress with limited design freedom
Solution Approach 1:
The patent divides the single fastening function into two separate screw/nut assemblies positioned at different locations. Each assembly fastens to a different tangential end side of the passageway, segmenting the stress distribution and avoiding concentration at the radial summit.
Solution Approach 2:
The patent transitions from a single-dimension fastening approach (one screw through the center) to a two-dimension distributed fastening approach (two screws at opposite tangential ends), changing the spatial arrangement to reduce stress concentration at critical locations.
2Ease of operation
If the through-passageway width is equal to the screw diameter to achieve tangential hold, then the balance weight is secured, but the service life of the balancing flange remains too short due to high stress concentration
Solution Approach 1:
The fastening function is segmented into two separate screw assemblies, each handling one tangential direction. This segmentation allows the passageway width to be greater than the screw diameter, creating a more favorable stress distribution and extending service life.
Solution Approach 2:
The patent applies different fastening configurations to different locations: two separate screw assemblies at opposite tangential ends rather than a single central assembly. This local differentiation optimizes both retention and stress distribution.
3Device complexity
If a single screw/nut assembly is used through the passageway, then the structure is simple, but the radial end portion of the passageway is subjected to high tangential stresses
Solution Approach 1:
The single fastening assembly is segmented into two separate assemblies positioned at opposite tangential ends. While this increases component count, it dramatically reduces stress concentration by distributing the loading across two separate locations rather than concentrating it at the radial summit.
Data Source
AI summary
The present invention relates to a turbomachine rotor balancing system comprising a balancing flange (52) provided with through-passageways (78), the system further comprising balance weights (54) each mounted fixedly on the flange (52) by means of a first and a second screw/nut assembly (56a, 56b) having a first and a second screw (84, 84) passing through a first and a second passageway (78, 78). According to the invention, said first screw is pressing against a first tangential end side (116) of the first through-passageway, and at a distance from a second tangential end side, and the second screw is pressing against a second tangential end side (118) of the second through-passageway, and at a distance from the first tangential end side.