This article focuses on the mathematical model of the pitch control mechanism for a marine controllable pitch propeller, with the aim of describing the dynamic behaviour of this kind of system and its influence on ship performance. Too great a load on the blades can result in high pressures in the actuating system, response delays and control system problems, which are ultimately responsible for most mechanism failures. The behaviour of the controllable pitch propeller actuating mechanism is considered in terms of blade position, oil pressures inside the controllable pitch propeller hub and magnitudes of the forces acting on the blades. In the proposed mathematical model, the forces acting on the propeller blade are evaluated taking into account the yaw motion of the ship, the propeller speed (including shaft accelerations and decelerations) and the turning of the blade during the pitch change. On the basis of the introduced procedure, a controllable pitch propeller numerical model as part of an overall propulsion and manoeuvrability simulator representing the dynamic behaviour of a twin-screw fast vessel is developed. The aim of this work is to represent the ship propulsion dynamics through time-domain simulation, based on which the designers can develop and test several design options, in order to avoid possible machinery overloads with their consequent failures and to obtain the best possible ship performances. In this aspect, the controllable pitch propeller model is an essential design tool.
A turbocharged diesel engine numerical model, suitable for real-time ship manoeuvre simulation, is presented in this paper. While some engine components (mainly the turbocharger, intercooler and manifolds) are modelled by a filling and emptying approach, the cylinder simulation is based on a set of five-dimensional numerical matrices (each matrix is generated by means of a more traditional thermodynamic model based on in-cylinder actual cycle). The new cylinder calculation approach strongly reduces the engine transient computation time, making it possible to transform the simulation model into a real-time executable application. As a case study, the simulation methodology is applied to a high speed four stroke turbocharged marine diesel engine, whose design and off design running data are available from the technical sheet. In order to verify the suitability of the proposed model in real-time simulation applications, a yacht propulsion plant simulator is developed. Numerical results in ship acceleration and deceleration manoeuvres are shown, reducing the simulation running time of 99% in comparison with the corresponding in-cylinder actual cycle engine model.
The design of a dynamic positioning (DP) system is a challenging task with several technical fields involved in the problem solution. Numerical simulation is a powerful tool to aid the designer during the system development and to speed up the design process. This paper presents the simulation methodology adopted to design and test the DP system for a vessel with a standard propulsion configuration. Simulation results and sea trial measurements are compared to illustrate the reliability of the proposed simulation platform.
This work presents the main steps for the development of a multi-physic simulation platform, able to represent the dynamics of a twin screw ship in six degrees of freedom, taking into account the complete propulsion system including automation effects. The simulation platform has to be used in the preliminary design phase in order to study and design the propulsion plant and its control system. The ship motion model has been developed including roll motion, in order to capture the ship heel angles during tight turning circles, which may be significant for a fast naval vessel. Moreover, the simulation model includes a simplified representation of the asymmetric behaviour of the two propeller shafts during manoeuvres, which cannot be neglected when dealing with the propulsion plant behaviour. Several sub-models have been developed and calibrated by means of a set of experimental tests, in model and full scale. The sea trials campaign is finally used to validate and tune the developed simulator, thus the final version may be adopted as an optimization tool for other future designs (or sister ships) and for training purposes. Although the presented case study has been validated on a specific ship, most of the discussed models have a general application
scite is a Brooklyn-based startup that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.