Computational investigation of ship propulsion performance in rough seas

In this paper, the performance of a merchant vessel propulsion system during acceleration is evaluated under different sea state conditions. The various parts of the main propulsion system have been modelled by using a mean value approach for the engine model with differential equations to calculate the engine crankshaft and turbocharger shaft speeds. Ship propulsion system has been modelled by using differential equations to calculate vessel speed and speed of advance. The output of the engine model has been validated under steady conditions according to the main engine shop test performance data. The calm water resistance is calculated following the ship sea trials results, whilst Wageningen polynomials have been used to simulate the propeller performance for the given hull resistance and speed. In order to estimate the added resistance for different weather conditions, the recommended procedures by International Standards have been followed. Then, the propulsion system performance is evaluated, both in calm water and waves, to investigate the main engine response during acceleration. Based on the simulation results, the propulsion system performance is discussed in respect for the engine response and vessel hydrodynamic performance, predicting the maximum vessel speed for the available engine power and speed

Numerical study of propulsion system performance during ship acceleration

Ship acceleration manoeuvre is important in terms of safety and engine performance. Head seaways are one of the most challenging conditions for the ship propulsion. A detailed simulation of the propulsion system’s transient response during dynamic acceleration in harsh conditions can result in a thorough investigation of the engine performance, a better management of control system and the monitoring of engine limiters application in real conditions. For the overall propulsion system performance assessment during ship acceleration, a computational tool has been developed that comprises sub-systems for the simulation of engine, turbocharger, propeller components and their interaction. The developed tool has been validated against available shop and sea trials data and then it has been tested for the simulation of propulsion system performance during acceleration in dynamic conditions. Based on the simulations results, a sensitivity analysis has been performed for the investigation of the governor control unit limiters that apply on the engine during acceleration. As a result, the effect of engine governor limiters on the overall engine and hydrodynamic performance of the ship during acceleration is quantified and discussed

Παραμετρική Διερεύνηση Πολυζωνικού Μοντέλου Καύσης για τη Βελτίωση της Προβλεπτικής Ικανότητας σε Κινητήρες Diesel Άμεσης Έγχυσης

114 σ.Παραμετρική Διερεύνηση Πολυζωνικού Μοντέλου καύσης για τη Βελτίωση της Προβλεπτικής Ικανότητας σε Κινητήρες Diesel Άμεσης ΈγχυσηςParametric Investigation of a Multi-zone Combustion Model to Improve the Predictive Capability on direct injection Diesel EnginesΠαναγιώτης Π. Μηζύθρα

Sensitivity analysis of the tool for assessing safe manoeuvrability of ships in adverse sea conditions

In 2013, International Maritime Organization (IMO) introduced the Interim Guidelines for determining the minimum propulsion power to maintain the manoeuvrability of ships in adverse conditions. Considering the sufficiency of propulsion system in adverse sea conditions, the European project SHOPERA has developed alternative processes and tools for assessing safe manoeuvrability of ships. The main objective of these procedures is to identify the critical conditions where the vessel maintains its course keeping and manoeuvring ability at the vessel available propulsion power by using basic ship design values as input into the simplified methods proposed. Outcomes of this project were submitted and discussed in the 70th session of IMO’s Marine Environmental Protection Committee. In this paper, a brief description of these new assessment procedures is presented and a sensitivity analysis is conducted. The analysis is performed for a range of different open water propeller and hull resistance characteristics, hull – propeller interaction factors and engine power limit values, investigating the influence of these various performance parameters on the performance of the vessel