10. SUMMARY
The authors proposed and careful investigated the following concepts:
a) The active torsional vibration control for large two stroke marine diesel engines.
b) The amplitude decrease of the resonant harmonic in the barred speed range while keeping mean indicated pressure and engine torque on the propeller law.
c) An electronic fuel strategy for a favourable combustion rate by a refined injection characteristic with a pilot injection and delayed combustion.
11. CONCLUSIONS
The study proved by calculations that much potential in the active control of torsional vibration of the ship shafting lies in the pilot injection and delayed combustion timing. This can bring for a precisely delayed combustion law, a smooth passing through very active resonance with three times lower additional torsional stress but with the penalty of a more complicated electronic fuel injection management. A new injection law would be necessary coupled eventually with an additional heating of the fresh charge. This study brings a contribution in the complex field of torsional vibrations. More research is needed to clarify all the aspects involved and to develop these ideas to a final result.
12. ACKNOWLEDGMENT
The first author would like to thank to all the colleagues from System Dynamics and Vibration Analysis at Wartsila NSD and especially for the support and suggestions that he received from Mr. N. Ly, Mr. R. Wyss and Mr. H. Keller during this study, and for the valuable talks with Dr. W. Shiffer. Special thanks to Mr. F. Porchet from Wartsila NSD and Mr. H. Fritschi from Sulzer Brothers Ltd, that offered the opportunity and the good conditions for an efficient work environment.
Many thanks to I. Mihailescu and A. Anghelache for the kind help for the text processing.
13. REFERENCES
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