Dynamic Behaviour Analysis of a Sequentially Turbocharged Marine Diesel Engine

Abstract: The paper reports and discusses the results obtained by the application of a theoretical simulation to a sequentially turbocharged marine diesel engine, with the aim to predict the transient variation of some in-cylinder and overall parameters as a consequence of the engine speed and load variation. The simulation model is applied to the behaviour prediction of the Wärtsilä 18V 26X engine, a highly rated, recently developed, sequentially turbocharged marine diesel engine, when the load is varying according to the propeller load. The analysis is focused in particular to the second turbocharger switching-in/out operations, in order to evaluate the thermal and mechanical stresses induced to cylinder, piston and cinematic member during these phases. A two-zone actual cycle calculation scheme is used for the in-cylinder phenomena description. The model used to simulate the engine-load dynamics, already presented and discussed in previous papers, has been modified and improved in the present application by introducing suitable engine governor and fuel pump sub-models, expressly developed and discussed in the paper.