A nonlinear optimization tool to simulate a marine propulsion system for ship conceptual design

An optimization tool is developed to simulate the performance of a marine propulsion system of a fishing trawler for ship conceptual design. It consists of two modules implemented in Matlab. The first optimization module simulates the performance of a high speed turbocharged four-stroke marine diesel engine along the engine load diagram. It couples 1D engine simulation tool and a nonlinear optimizer to minimize the BSFC of the marine engine and to verify the limitations of emissions defined by international organizations, by optimizing turbocharger and injection parameters. The second module assists in the selection of a suitable fixed pitch propeller from Wageningen B-series at the ship design speed at engine operating point with minimum fuel consumption and by verifying the propeller cavitation, strength and noise issues, instead of only maximizing the propeller efficiency or minimizing the BSFC as considered in previous researches. Then, the objective of the propeller optimization module is changed to compute the propeller performance by (1) maximizing the propeller efficiency (2) minimizing the BSFC, for the purpose of comparison with the current study. The current case shows a significant reduction in the amount of fuel consumed by around 30% in comparison with the other two cases.