Performance Prediction of a Faulty Marine Diesel Engine under Dif- Ferent Governor Settings

Various methods are proposed in literature for the engine faults detection, based on the combination of simulation models with measured engine data. In order to be effective, these methods must be based, in author’s opinion, on detailed, reliable and validated simulation models, able to predict the faulty engine performance, by reproducing its actual work conditions. This is particularly important in case the simulator is used for the diagnosis of faults or for the engine maintenance staff training. The aims of the paper are: firstly, to verify the suitability of the author’s diesel engine model to be used for the faults simulation; secondly, to analyse and compare the influence of the engine governor logic on the performance alterations of a faulty four stroke turbocharged marine diesel engine. The adopted diesel engine simulation model is based on a two-zone cylinder combustion scheme, which allows a detailed calculation of the thermodynamic processes inside the cylinders. The thermodynamic study of the in-cylinder phenomena is combined with a simulation of the behaviour of the turbocharger, of the intake and exhaust systems (intercooler, manifolds, etc.) and of the fuel pump. The engine faults analysed in the paper, selected on the basis of indications given by the engine maintenance staff and drawn from bibliography observations, are related to the fuel injection system and to the exhaust manifold behaviour. The reported analysis and the presented results, relative to the engine performance variation as a consequence of the simulated faults (at different intensity levels), show the validity and the flexibility of the used diesel engine simulator in predicting fault situations. In particular the simulated engine working parameters present a different variation depending on the adopted engine governor logic.