How do I consider propeller damping in torsional vibration calculations?


Torsional vibration analysis

Propeller damping plays an important role in torsional vibration analysis.

In the Nauticus Torsional Vibration tool, five different methods of damping calculation are available:

  • Archer approach: Consider the propeller damping as a consequence of the propeller’s torque characteristics. Derive the damping coefficient from the propeller law. Suitable for both fixed pitch propeller and controllable pitch propeller.
  • Frahm approach: Similar to Archer approach but using Frahm number.
  • Schwaneke approach: Use Schwaneke empirical formula to calculate the propeller damping. It is dependent on the propeller geometry.
  • Dynamic magnifier approach: Use the dynamic magnifier/dynamic magnifier percent to simulate the propeller damping. It is often used for MAN propellers.
  • Variable approach: The dynamic magnifier percentage changes as function of propeller rotational speed.
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