1. Pressure pulsations in Francis turbines
Peter Joachim Gogstad

2. Background Hydropower turbines have suffered Excessive vibrations
Fatigue damage
Limited operating conditions
Hydroturbines have been a part of energy generations for decades. Development towards higher efficiency, lighter turbines and increased flexibility have been the driving force the last decade. This has resulted in more turbines experiencing vibrations, fatigue damages. This again have limited operating conditions to close to BEP. Introduction of more renewable energy producers as wind and solar, has increased the demand for flexibility in hydropower operation.

3. Objective Why do we have pressure pulsations?
Why are some turbines so severly affected by pressure pulsations?
How can they be mitigated or reduced most efficiently?

4. Case Leirfossene
Problems with vibration
Air injection
Measurements

5. Francis turbine

6. Rotating Vortex Rope
The pressure pulsation amplitude is believed to be related to the highest velocity detected in vortex

7. Runner Cone Extension Locked or freely rotating 3 different lengths
The pressure pulsation amplitude is believed to be related to the highest velocity detected in vortex

8. Runner Cone Extension
The pressure pulsation amplitude is believed to be related to the highest velocity detected in vortex

9. Results Efficiency unchanged Reduced pressure pulsations
Length and diameter dependent

10. Further work Measurements in Lerifossene Different designs Efficiency
Pressure
Vibrations

11. Questions?