Supercritical Shaft Balancing with Adjustable Annular Insert
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbomachine shafts operating at supercritical speeds experience excessive vibrations and whirl instability due to first-order beam bending modes within the standard operating range, which existing balancing methods, such as bearing dampers and balance lands, are unable to fully mitigate.
Innovation Solution
The implementation of balancing devices, such as annular inserts and solid disc assemblies with adjustable weights and insertion tools, which can be positioned and oriented within the shaft to minimize displacement and stabilize the supercritical shaft during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearing dampers and balance lands are used for balancing, then some vibration reduction is achieved, but excessive vibrations and whirl instability remain at supercritical speeds
Solution Approach 1:
The shaft is divided into multiple balancing planes, and the balancing device is segmented into adjustable mass elements that can be independently positioned on different planes. This allows targeted counterbalancing of specific vibration modes without affecting other operational characteristics.
Solution Approach 2:
The balancing device incorporates adjustable mass elements that can be repositioned along the shaft axis and rotated to different angular positions. This dynamic adjustability enables optimization of balancing effectiveness for different operating conditions and vibration modes, particularly at supercritical speeds.
2Ease of manufacture
If traditional balancing methods are applied, then manufacturing simplicity is maintained, but the ability to mitigate vibrations at critical speeds is insufficient
Solution Approach 1:
The balancing device is pre-configured with adjustable mass elements and positioning mechanisms during manufacturing. This preliminary preparation allows for field adjustment and optimization without requiring complex manufacturing processes or specialized equipment at the balancing stage.
Solution Approach 2:
The device incorporates adjustable components that enable field modification of balancing parameters. This dynamic capability allows optimization of vibration mitigation effectiveness after installation, without compromising the relatively simple manufacturing process.
3Device complexity
If balancing weights are fixed in position, then device complexity is reduced, but adaptability to different vibration modes and speeds is limited
Solution Approach 1:
The balancing device features mass elements that can be adjusted in position along the shaft axis and rotated to different angular orientations. This dynamic adjustability provides adaptability to different vibration modes and operating speeds while maintaining a relatively simple overall device structure.
Solution Approach 2:
Different sections of the balancing device have specialized functions: some portions provide axial adjustment capability while others enable rotational positioning. This local differentiation of qualities allows comprehensive adaptability without requiring complex integration across the entire device.
Data Source
AI summary
A device for balancing a shaft in a turbomachine engine includes an annular insert configured to be positioned inside the shaft at any axial position along the shaft, and a weight that is attached to the annular insert at any angular position inside the shaft.