Model based prediction of the crankshaft instantaneous angular speed fluctuations

The paper presents results of the calculation, based on simplified engine model, aimed on prediction of IAS (Instantaneous Angular Speed) of the crankshaft fluctuations under faulty engine condition. Gas forces were calculated basing on results of in-cylinder pressure measurements which were used as inputs to the dynamic model. Mass forces were calculated basing on technical particulars of the engine Sulzer 3Al 25/30.Measurements of the incylinder pressure was carried out at laboratory stand in Gdynia Maritime University, equipped with diesel engine Sulzer 3AL 25/30 driving electro-generator. Sulzer 3AL 25/30 is three cylinder, medium speed, four stroke marine diesel engine, with maximum output 408 kW at 750 rpm. In order to evaluate of IAS model utility for diagnostic prediction of the engine behavior, two kinds of malfunctions of engine’s fuel system were simulated. First malfunction was fuel leakage from high pressure line; the second was partly plugged injector’s nozzle. Construction of high pressure fuel pump enable to fuel leakage simulation. The engine was run out at load 250 kW what is around 65% of nominal. Results of all measurement were smoothed in order to eliminate a noise using SG (Savitzky – Golay) filter. Results of fault condition modeling were compared with healthy engine model and with results of in -cylinder pressure diagrams, in order to create a map of deviations from normal condition.