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Σύνδεση με προνόμια ΕΛ.Ι.Ν.Τ.

Integrated Simulation Model of Ship Hull, Propeller and Propulsion Engine for Performance Prediction and Fuel Consumption Reduction

George Papalambrou, Stefanos Glaros, Emmanuel Angelou, Nikolaos Kyrtatos
NTUA

Abstract

A dynamic simulation tool for ship propulsion power train optimal performance at real service conditions was developed. Real service conditions differ from trial conditions, as they include environmental disturbances and several transient loadings. In addition, a service profile of a ship includes operating profiles that are different from trial conditions, for example maneuvering or overload. In order to optimize the power train for such operation, it is necessary to understand the influence of unsteady loadings on overall power train efficiency and its components.

 

In this work, dynamic models of different components such as hull, engine, propeller, autopilot etc. were integrated into one model of power train, which then was used to investigate the influence of service conditions, as well as unsteady loadings on overall efficiency. The unsteady loadings examined include autopilot course keeping, engine acceleration and deceleration, ship in seaway with wind and waves, sailing through brash ice channels and ramming of ice ridges. After understanding this influence, an optimization of a ship power train for its service profile was carried out. Given an operational profile (i.e. ship routing and weather), optimization algorithm estimated engine speed demand that fulfills requirements such as fuel consumption and vessel speed not to exceed specified limits or constraints. This paper presents some results, which show that the predicted improvement from optimization algorithm was achieved with success.

1. Introduction

There is significant number of ship maneuvering modular simulation models that have been developed and published in the related literature. Their detail varies according to their purpose, as models that seek to perform a stability analysis of the ship are in general of greater complexity in contrast to models where a little more of a crude description of the behavior of the ship is considered adequate, as the target is to examine the transient effects on power plants.

In the first case the models usually involve state of the art CFD(1) viscous or potential codes and a heavy computing time, making them unattractive for a coupling with a power plant model.

In the second case ship models tend to be simpler and their various components are simulated either using empirical equations or measured data from full or model scale tests. In a literature survey one can notice that the higher the detail of the power plant modeling, the lesser the detail of the ship maneuvering model. In this review we refer to a few of them, as their implementation is considered representative of the modular modelling, but not necessary more innovative than others which are not mentioned here.

The simulated detail can vary between 1 to 6 DoF(2) though the most common choice includes some or all of the planar DoF. Livanos et al. [1] used a one DoF (surge) model to simulate the dynamics of marine diesel engine propulsion systems, during extreme maneuvering. The modeled propulsor was a CPP(3), while the engine model consisted of validated engine map data from LME simulation code MOTHER(4). Benvenuto et al [2] used a 3 DoF model with a CPP and medium speed diesel engines along with sea trials available ship data, to simulate ship propulsion systems, as a tool of optimization during the initial phase of the design process when the choice of the propulsion system components has to be made, and to predict the behavior of the propulsion plant during critical situations.

Kruger et al [3], developed a 3 DoF (surge,sway and yaw) simulation model taking into account hydrodynamic and aerodynamic, propeller and rudder forces. Hull forces where approximated by model test data, Wind forces where modeled using wind tunnel tests,  Rudder forces where modeled by applying a vortex lattice method, while for the propeller available CPP KT,KQ curves where interpolated between different pitch positions and for the four quadrants in order to simulate the operating conditions that occur during off-design situations like crash-stop maneuvers. This model was coupled [4] with a four-stroke engine in order to study the performance of the power plant during basic ship trial maneuvers.

Kopp [5] developed a 4 DoF (surge,sway, roll and yaw) model where hull, propeller, rudder forces, as also the forces that were induced due to the influence of waves, where interpolated through available model test data. The power plant included four diesel engines, whose transient characteristics were examined during station-keeping operations. 

A dynamic simulation tool for ship propulsion power train optimal performance at real service conditions is presented in this paper. The application example refers to a typical tanker hull equipped with a 2-stroke marine propulsion diesel engine.

This paper has the following layout. Following the short introduction with literature review in Section 2 Ship model is presented. In Section 3 the engine model is reported. Results from simulation are shown in Section 4. Optimization is presented in Section 5 and Section 6 gives conclusions.

Το πληρες άρθρο είναι διαθέσιμο μόνο για τα μέλη ΕΛ.Ι.Ν.Τ.
Αν είστε μέλος παρακαλούμε συνδεθείτε με τον κωδικό σας.
Για να γίνετε μέλος ΕΛ.Ι.Ν.Τ. ακολουθήστε τις οδηγίες στις Εγγραφές Μελών
Τετάρτη, 24 Απριλίου 2013

TRAINING WORKSHOP, ΠΟΥ ΟΡΓΑΝΩΘΗΚΕ ΑΠΟ «ΕΛΙΝΤ» / «MAR.TEC.M.A.» / «Ε.Ε.Δ.Ε.» ΣΤΙΣ 19 & 20 ΑΠΡΙΛΙΟΥ 2013, ΣΤΑ ΠΛΑΙΣΙΑ ΤΩΝ ΕΚΔΗΛΩΣΕΩΝ:
«ΗΦΑΙΣΤΟΣ 2013» / ΑΘΗΝΑ & «HE.M.E.EXPO. 2013» / ΣΑΓΚΑΗ

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