Model Based Prediction of the Crankshaft Instantaneous Angular Speed Fluctuations

Abstract

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.

Total loss torque waveform estimation for a turbocharged diesel engine

“…The Figure (4) shows a series of total loss torque obtained for the gas pedal position α=0,45. From this Figure we notice that the evolution of the total lost torque is proportional to the rotational speed.…”

“…This measured parameter was largely exploited. Various studies have estimated indicated torque and eventually in-cylinder pressure using crankshaft angular speed measures injected in a rigid-body or elastic-body engine model built from the second Newton's law [3,4]. The indicated torque reconstruction from crankshaft speed fluctuations can be achieved with two main approaches, mathematical models and database-based methods like explained in the reference [5,6].…”

Method of evaluation of the technical condition of the diesel-electric unit

“…The technical condition of an engine exerts direct impact on the course of the working process occurring in the engine cylinders. Consequently it has an impact on fluctuations of the angular velocity of its crankshaft [3,9,10]. Fluctuations of the angular velocity of the crankshaft translate into fluctuations of the angular velocity of the generator rotor.…”