Cavitation Observations and Analysis

Cavitation not only has enormous impact on turbine/pump efficiency, it can cause significant damage to turbine and pump components. Therefore, during our model testing programs, cavitation phenomena are typically observed over the entire operating range of the turbine/pump in order to determine under what conditions (e.g., tailwater level of the prototype) cause the occurrence of blade profile or leakage cavitation.

 Cavitation Figure

Sigma break curves are measured in order to determine the safety margin between plant sigma and critical sigma (1% efficiency drop). These curves are typically accompanied by observations sketches, photos and videos. Often multiple runners can be directly compared under the same test conditions, such as in the example to the right. Cavitation Curves

Typical cavitation behavior studied

  • Cavitation behavior at plant Thoma number, including observations of suction side cavitation, pressure side cavitation, leading edge cavitation, leakage cavitation near the hub and near the Plexiglas wall and the rope (both partial and high load ropes)
  • Observation and measurement of incipient Thoma number, at the beginning of suction side cavitation on the surface of all blades.
Cavitation Behavior