Turbomachine Rotor Disc Balancing via Variable Volume Scallops
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Solution Overview
Problem
Existing methods for balancing a turbomachine rotor disc, such as using balance cables or rivets, are weight-penalty inducing and face challenges with limited space for installation due to fixed geometry and tool passage requirements, making them complex to implement effectively.
Innovation Solution
A rotor disc design featuring a radial flange with varying fastening holes and scallops, where some scallops have greater volumes and inter-scallop flange portions have lesser volumes, allowing for imbalance correction without adding balancing weights, and a method to measure and machine these features to achieve balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If balance cable or rivets are installed to correct imbalance, then the disc is balanced, but the overall weight increases and installation space is insufficient
Solution Approach 1:
The invention extracts material from the flange by creating scallops (material removal) instead of adding balancing weights. The scallops are notches or cavities machined into the flange that remove mass from specific locations to correct imbalance, thereby achieving balancing without increasing overall weight.
Solution Approach 2:
The invention changes the volume parameter of the flange by creating scallops with different volumes. By controlling the volume and location of material removal through scallops, the mass distribution is altered to achieve balance without adding external weights.
2Reliability
If balance cable or rivets are installed to correct imbalance, then the disc is balanced, but the device complexity increases due to limited space and tool passage requirements
Solution Approach 1:
The balancing function is extracted from external components (cables, rivets, weights) and integrated directly into the flange structure itself. The scallops are formed as part of the flange geometry, eliminating the need for separate balancing components and reducing installation complexity.
Solution Approach 2:
The balancing function is merged with the structural flange component. The scallops serve dual purposes: maintaining structural integrity of the flange while simultaneously providing the mass distribution needed for balancing, thereby reducing the number of separate components and simplifying installation.
3Weight of moving object
If scallops with varying volumes are created in the flange, then the disc is balanced without adding weight, but the manufacturing precision requirements increase
Solution Approach 1:
The flange is designed with local variations in material distribution through scallops of different volumes at specific locations. Each scallop's volume and position are optimized locally to address specific imbalance conditions, allowing precise mass distribution control without requiring extremely tight manufacturing tolerances across the entire component.
Data Source
AI summary
A rotor disc (1) for a turbomachine, including a radial flange (2) that includes a plurality of fastening holes (3), and a plurality of scallops (4) forming notches in the flange (2), and being separated by inter-scallop flange portions (7). The flange alternatively has, in its circumferential direction: a fastening hole (3) and an inter-scallop flange portion (7) arranged in the radial extension of the fastening hole (3), and a scallop (4), in such a way that one or more of the scallops (47, 48, 49; 42, 45-47, 48-411, 414) has a volume greater than the volume of each of the other scallops (41-46, 410-414; 41, 43, 44, 412, 413), and one or more of the inter-scallop flange portions (73) has a volume less than the volume of each of the other inter-scallop flange portions (71, 72, 74), in order to balance said disc (1). A turbomachine including that rotor disc and a method for balancing a turbomachine rotor disc are also disclosed.