On the Relationship of Torsional Vibrations and Breakdown Torque of Marine Diesel Engines

Abstract

The article provides an overview of the conditions necessitating the calculation of torsional vibrations and disturbing moments relevant for their calculation as for marine diesel engines followed by an analysis of the effect of torsional vibrations on the breakdown torque of the engine. The forces arising in the crank mechanism of the engine due to torsional vibrations are illustrated by a diagram. Formulas are suggested for calculating the breakdown torque caused by torsional vibrations of the crankshaft of a multi-cylinder engine and the total breakdown torque. It is recommended to consider the influence of moments caused by torsional vibration on the unevenness of rotation and vibration of the engine.The results of calculation of the total torque of the engine previously performed by group of researchers, considering the influence of torsional vibrations, are quoted for DGR A 100/750 diesel generator with an effective power of 100 kW at a nominal speed of 750 rpm with a 6L 18/22 engine.Based on the results of the analysis, suggestions are given on the need to consider the moments arising from torsional vibrations when diagnosing the engine.