VIBRATION PROBLEMS OF PROPULSION SYSTEMS IN LARGE NAVAL SHIPS.

Defects in the drive system such as mass unbalance in the turbine rotors and propeller, misalignment in the couplings of the propeller shaft, transmission errors in the reduction gearing systems and flexibility of the propeller shaft are some common vibration problems. Apart from these, propeller induced vibrations due to hydrodynamic force variations play a major role. These are mainly due to inadequate tip and bossing clearances and are produced as a result of the propeller blade tip hull interaction. Detection of the sources of vibrations in the propulsion systems using vibration signature analysis techniques is explained. A typical case study of propeller induced vibrations of a naval ship is discussed to enhance the need for understanding the problems.