Session: 06-08-01 Model Tests - I

Submission Number: 175418

Experimental Testing of a Vessel in Following Waves 

We report the details of a broad model test campaign performed on a general cargo vessel, the Eidsvaag Pioner, as part of a larger research project focused on the reduction of energy consumption in waves.

Reducing the energy consumption of seagoing vessels operating at sea is critical, in order to meet the present and oncoming requirements to reduce greenhouse gas emissions which result from global fleets of vessels serving the world’s shipping needs.

Large research efforts have been invested over recent decades in optimising a ship’s capability to operate efficiently in waves. However these optimisations have primarily focused on hullform and propulsion optimisation such that added resistance in head waves is minimised. In following waves, past studies have primarily focused on the issues related to dynamic instability effects. The ability of a vessel to proceed efficiently in following seas is less well established, but offers the potential for efficiency gains through a variety of physical effects.

In order to establish the feasibility of optimising steering and propulsion application for following seas, as well as identifying beneficial combinations of wave headings and encounter periods to guide routing of the vessel, a program dedicated to achieving effective benchmark model test data has been focused on as part of the project, “Ship operational performance in following seas”, funded by the Norwegian Research Council.

This work contributes to understanding the physics involved in solving seakeeping and manoeuvring problems in which the frequencies of motion for the two domains overlap and interact. For instance, when operating under automatic control, vessels’ control algorithms may be optimised to filter out wave frequencies, but may be less well suited to achieving performance improvements which take advantage of the waves passing the vessel. Different approaches may instead be used in altering the usage of the rudder and propeller to rather work with the waves and extract some non-negligible portion of energy from these wave trains as they pass by. The establishment of these approaches is heavily dependent on effective knowledge of the hydrodynamic effects of the vessel transiting the seaway. The development of effective hydrodynamic theories and models is strengthened through reference to a well established benchmark dataset of model tests.

A diverse model test campaign has been performed on the Eidsvaag Pioner, a modern general cargo vessel typically operating on Norwegian short sea routes. In this paper, we will present key results and findings from the various test campaigns conducted in the project. Furthermore, the relevance of these findings for guidance on energy efficient operation and for improving numerical models will be discussed.

The paper will be organised in the following structure:

1.       Motivation: the background to the project and test campaign will be detailed, with reference to the vessel’s primary usage.

2.       Model particulars: the constructed vessel will be detailed, with emphasis on the measurement techniques and newly developed instrumentation which were used to gather data of high quality and low uncertainty.

3.       Model test campaigns: the main portion of the paper will be to detail the types of tests carried out on the model. These tests include:

a.       Calm-water reference tests

b.       Self-propelled tests in a softly moored system at a variety of wave heights and wavelengths and at various configurations of propulsion.

c.       Self-propelled tests with free running model on autopilot for at a variety of realtive wave headings, wave heights and wavelengths and at various configurations of propulsion.

d.       Planar motion mechanism (PMM) tests consisting of various prescribed motion tests at forward speed in varying following wave conditions at low positive and negative encounter frequencies, centred around an encounter frequency of zero.

e.       Free running manoeuvring tests consisting of various standard manoeuvres in calm water and in initially following waves.

4.       Data usage: emphasis on what purposes the data is of particular use the data has, and for what purposes it can be put to use for.

Presenting Author: Andrew Ross SINTEF Ocean

Presenting Author Biography: Dr. Andrew Ross is a Senior Researcher in Ship Hydrodynamics at SINTEF Ocean, based in Trondheim, Norway. He has a PhD in Marine Cybernetics from the Norwegian University of Science and Technology. With nearly twenty years of experience in the maritime research sector, Dr. Ross has deep expertise in ship model testing, vessel manoeuvring, and simulation of ship behaviour in open, confined, and coastal waters. At SINTEF Ocean, he leads and contributes to research and development projects involving experimental and numerical studies of manoeuvring, and validation of simulation tools for maritime operations.

Authors:

Andrew Ross SINTEF Ocean
Vahid Hassani SINTEF Ocean
Min-Guk Seo KRISO
Anders Alterskjær SINTEF Ocean
Øyvind Rabliås SINTEF Ocean