Variable Guide Bearing Clearance Adjustment for Turbine Vibration
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Solution Overview
Problem
Hydroelectric turbine assemblies experience shaft vibrations due to variations in radial guide bearing clearance, which can lead to unsafe startup conditions and potential damage from thermally induced clearance changes and upset events, such as hydraulic disturbances or electrical faults.
Innovation Solution
A system that continuously monitors and adjusts the radial clearance between guide bearing pads and the shaft using a pad adjuster system actuated by a prime mover, with a gearing system engaged non-collinearly to protect against back driving forces, ensuring optimal clearance during operation and mitigating the effects of thermal expansion and upset conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the radial guide bearing clearance is fixed during manufacturing, then the manufacturing precision is improved, but the reliability deteriorates due to thermal expansion and upset conditions causing clearance variations
Solution Approach 1:
The guide bearing pads are made adjustable through a mechanism involving adjustment bolts and locking nuts, allowing the radial clearance to be dynamically modified. This enables the bearing clearance to adapt to thermal expansion and upset conditions, resolving the contradiction between fixed manufacturing precision and operational reliability.
2Reliability
If a variable guide bearing system with adjustment mechanism is implemented, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The adjustment mechanism incorporates locking nuts that secure the adjustment bolts in position, allowing the system to maintain its adjusted clearance without continuous external intervention. This self-locking feature reduces the need for complex active control systems while maintaining reliability.
3Adaptability or versatility
If the guide bearing pads are made adjustable, then the adaptability is improved, but the ease of operation deteriorates due to additional adjustment and locking procedures
Solution Approach 1:
The adjustment bolts and locking nuts are pre-configured in the bearing assembly, allowing for straightforward adjustment procedures. The locking nuts are designed to be engaged after adjustment, providing a simple two-step process that maintains ease of operation while enabling adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively maintains optimal radial guide bearing clearance, reducing vibrations and protecting against back driving forces, thereby ensuring safe operation and preventing damage to the turbine-generator assembly.
Implementation Method 1
the width of the radial guide bearing clearance can differ significantly depending on the bearing system's ambient temperatures
Implementation Method 2
Ideally, the shaft spins against a film of fluid annularly disposed between the guide bearing pads and the rotating shaft
Data Source
AI summary
A guide bearing system including a pad adjuster to traverse at least one bearing in a direction to adjust a radial clearance. The system can further include a sensor for measuring deviations in the radial clearance. In some embodiments, the guide bearing system includes a controller that receives a distance signal from the sensor measuring the radial clearance and signals the pad adjuster to traverse the at least one bearing to compensate for the deviations in the radial clearance.