Two-part modelling approach for ship engine simulations

When simulating a ship propulsion system, it is often required to evaluate various characteristics of a ship propulsion system and the selected modelling approach changes according to the goal of the simulation. For example, data-based models are sufficient for simulations of steady state conditions while first principle models are more suitable for transient conditions. Additionally, it is often necessary to compare different propulsion configurations. For component models, this might require different modelling approaches to describe various performances and/or different sets of parameters used to describe different propulsion configurations. Even though there are various databases of ship component models, none of them allows the user to change the modelling approach or pre-set values of parameters used to describe the component models. In order to allow the changing of the modelling approach together with the parameters of the component models, a novel two-part modelling approach is proposed in this paper. The proposed approach separates the component model into two parts: process and parametric part. By adjusting the process part of the component model, the modelling approach can easily be changed. And by adjusting the parametric part of the component model, it is possible to adjust the component¿s characteristics and accommodate different configurations. In this investigation, a mean value first principle diesel engine model has been selected as a case study to demonstrate the flexibility of the proposed approach. As shown in the paper, the proposed approach allows the user to combine the benefits of a first principle model with the accuracy of the data based models. Additionally, the functional mock-up interface (FMI) standard has been used in the investigation to show that the proposed approach can be used in different software environments.