REDUCING THE VIBRATIONS CAUSED BY A MARINE DIESEL GENERATOR SET

This paper details work undertaken to investigate the use of pneumatic ally controlled vibration absorbers to reduce the vibrations caused by a G&M/Perkins six-cylinder diesel generator (DG) set. The DG set had a mass of approximately 1 tonne and reductions in vibration levels nea r the engine mounts of about 10 dB were achieved using four absorbers with a total active mass of 18 kg. The absorbers incorporated air spri ngs which have the advantage of a variable stiffness depending on the contained air pressure within the springs. The ability to continuously tune to a target frequency was offset by the non-linear stiffness of the air springs, which makes control of the absorbers more complicated . For the work reported in this paper, the absorbers were manually tun ed to the desired operating frequencies. Sensitivity trials for absorb ers detuned from the optimum frequency are also reported.