Ice Resistance Calculation Methods and Their Economic Impact on Ship Design

2015 ◽  
Author(s):  
Rüdiger U. Franz von Bock und Polach ◽  
Tõnis Tõns ◽  
Sandro Erceg
Keyword(s):  
Economic Impact ◽  
Model Tests ◽  
Empirical Formulas ◽  
Panel Methods ◽  
Ice Conditions ◽  
Resistance Prediction ◽  
Semi Empirical ◽  
Ice Resistance ◽  
Ice Model ◽  
Testing Design

A ship is an investment and built to create revenue. The decision whether the design of a ship is realized or not is therefore strongly affected by the natural obstacles of mission and route. The occurrence of ice along arctic routes is such an obstacle and affects significantly the resistance and the required propulsion power. Advanced simulation environments, such as panel methods or CFD do not exist yet for ice resistance calculations and hence semi-empirical formulations or model tests need to be employed to assess or validate a design. Ice model tests impose great expenses in terms of time and money, which often does not allow testing design variations. On the other hand, the results of semi-empirical formulas might be accompanied by significant uncertainties. The academic study presented in this paper is a transit simulation on the Northern Sea Route (NSR) for the ice-capable tanker MT Varzuga (formerly MT Uikku). The study evaluates the ice conditions along several NSR alterations and the ice resistance-related performance with available semi-empirical methods and ice model tests. Finally, the economic impact of the applied ice resistance prediction methods is evaluated and the differences are quantified.

The Resistance of Ice Breaking Ships Based on Model Tests

2015 ◽  
Author(s):  
Seong-Rak Cho ◽  
Kuk-Jin Kang ◽  
Sungsu Lee
Keyword(s):  
Model Tests ◽  
Design Stage ◽  
Preliminary Design ◽  
Factors Associated ◽  
Preliminary Design Stage ◽  
Level Ice ◽  
Resistance Prediction ◽  
Ice Resistance ◽  
Priority Factor ◽  
Ice Model

The two most important tasks of ice breaking ships are first to secure a sailing route by breaking the thick sea ice and second to sail efficiently herself for purposes of exploration and transportation in the polar seas. The resistance of ice breaking ships is a priority factor at the preliminary design stage; not only must their sailing efficiency be satisfied, but the design of the propulsion system will be directly affected. Therefore, the performance of ice-breaking ships must be accurately calculated and evaluated through the use of model tests in an ice model basin before construction starts. In this paper, a new procedure is developed, based on model tests, to estimate a ship’s ice resistance during continuous icebreaking in level ice. Some of the factors associated with crushing failures are systematically considered in order to correctly estimate her ice-breaking resistance, while the effects of the hull geometry, as reflected in the length, breadth, and draft of ships, are considered in calculating buoyancy and clearing resistance. Multiple regression analysis is calculated with each ice resistance component. This study is intended to contribute to the improvement of the techniques for ice resistance prediction with ice breaking ships.

Study on the Ship Ice Resistance Estimation Using Empirical Formulas

2014 ◽  
Author(s):  
Kyung Duk Park ◽  
Hyun Soo Kim
Keyword(s):  
Model Test ◽  
High Reliability ◽  
Main Idea ◽  
Estimation Technique ◽  
Empirical Formulas ◽  
Level Ice ◽  
Arctic Ice ◽  
Ice Model Test ◽  
Ice Resistance ◽  
Ice Model

The ice resistance estimation technique for icebreaking ships has been studied intensively over recent years to meet the need of arctic vessel design. Before testing in the ice model basin, the estimation of ship ice resistance with high reliability is very important to decide the delivered power necessary for level ice operation. The main idea of this study came from several empirical formulas by B.P. Ionov[1], E. Enkvist[2] and J.A. Shimanskii[3], in which ice resistance components such as icebreaking, buoyancy and clearing resistances were represented by the integral equations along the DLWL (Design Load Water Line). However, this study proposes modified methods considering the DLWL shape as well as the hull shape under the DLWL. In the proposed methodology, the DLWL shape for icebreaking resistance and the hull shape under the DLWL for buoyancy and clearing resistances are included in the calculation. Especially when calculating clearing resistance, the flow pattern of ice particles under the DLWL of ship is assumed to be in accordance with the ice flow observed from ice model testing. This paper also deals with application examples for a ship design and its ice model test results at the Aker arctic ice model basin. From the comparison of results from the model test and the estimation, the reliability of this estimation technique is discussed.

Theoretical Investigation on Ice Resistance Prediction Methods for Ships in Level Ice

2014 ◽  
Author(s):  
Daniela Myland ◽  
Sören Ehlers
Keyword(s):  
Physical Nature ◽  
Model Tests ◽  
Design Stage ◽  
Prediction Methods ◽  
Sufficient Information ◽  
Early Design Stage ◽  
Level Ice ◽  
Resistance Prediction ◽  
Ship Performance ◽  
Ice Resistance

The assessment of the ship performance in ice covered waters has become more and more important in view of the increased interest in Arctic field logistics and transportation. The performance of ice-going or ice breaking ships is usually defined by their ability to proceed in uniform level ice, where good performance means low ice resistance, high propulsion efficiency and continuous ice breaking. In order to assess the ice breaking performance in an early design stage, model tests may be executed or several theoretical methods may be applied to predict the ice resistance may be applied. Due to the physical nature of model tests, all processes, i.e. forces contributing to ice resistance are considered. Thus, the execution of model tests is still the most reliable method to determine the ice resistance. But with regard to the high costs of model tests there is continued demand to gain knowledge on the reliability of theoretical prediction methods. The applicability of the method of choice depends on the underlying assumptions of the method itself and thus the method’s capability to predict and consider physical phenomena of interest. In this paper model tests are used to evaluate the influence of hull shape parameters and ice conditions on the breaking process, i.e. the ice resistance and the ship performance. Based on the knowledge gained a systematic comparison of existing, representative ice resistance prediction methods is carried out. The methods considered are state-of-the-art techniques which the original publications introduced with sufficient information to allow for their use in this comparison. It focuses on the suitability of the existing methods as engineering tools for the prediction of different components, as well as the total ice resistance itself. The incorporation of the ice resistance contributions in the different prediction methods is presented and differences are identified. On this basis an assessment of the assumptions and simplifications of these different numerical methods is outlined.

Development of a Component-Based Scaling System for Ship-Ice Model Tests

1992 ◽  
Vol 36 (01) ◽  
pp. 77-87
Author(s):  
D. B. Colbourne ◽  
J. H. Lever
Keyword(s):  
Scaling Law ◽  
Model Tests ◽  
Experimental Procedure ◽  
Independent Components ◽  
Comprehensive Literature Review ◽  
Full Form ◽  
Scaling Parameters ◽  
Form Model ◽  
Ice Resistance ◽  
Ice Model

This paper presents the development and verification of a method for conducting and scaling ice resistance model tests based on division of the total resistance into three components. It is shown that each of these components is subject to a separate scaling law. A comprehensive literature review traces development of the concept of independent components in icebreaking resistance and covers development of nondimensional scaling parameters. A system of analysis and presentation is developed based on nondimensional parameters unique to each of the identified components. A set of experiments was carried out on a highly simplified full form model to verify the proposed experimental procedure. Data from these experiments demonstrate the excellent data collapse which can be achieved using the developed nondimensional presentation.

Methodology to Investigate the Icebreaking Process of Ships With Non-Typical Icebreaking Bow Shapes

2020 ◽  
Author(s):  
Quentin Hisette ◽  
Daniela Myland
Keyword(s):  
Ice Sheets ◽  
Relevant Information ◽  
Model Tests ◽  
Interaction Process ◽  
Analysis Procedure ◽  
Load Cells ◽  
Level Ice ◽  
Ice Resistance ◽  
Different Thickness ◽  
Ice Model

Abstract For non-typical icebreaking ships the hull-ice interaction process in level ice comprises a combination of many different phenomena which is difficult to be described by existing straightforward approaches. In order to gain knowledge about the level ice resistance of such non-typical hull shapes for operation in ice, a methodology is developed and presented to identify and evaluate the level ice resistance as well as its distribution along the hull of ships with non-typical icebreaking bow shapes with high stem and/or small waterline angles. For this purpose, one ship model has been manufactured and instrumented with several multi-component load cells in the bow region of the waterline as well as with one large six-component load scale between the bow and the stern. Performing resistance model tests at several loading conditions, in model ice sheets of different thickness and at multiple speed values allows obtaining relevant information to meet the goals of the study. The paper focuses on the methodology used for the ice model tests and its analysis. Instrumentation of the model is fully described, together with an overview of the testing matrix and model test observations. Analysis procedure is described in details and applied on a representative test run of the campaign.

Impact of Forced Roll Motion on the Ice Resistance of Modern Icebreaking Bow Geometries

2020 ◽  
Author(s):  
Johanna Marie Daniel ◽  
Tuomas Romu ◽  
R. U. Franz von Bock und Polach ◽  
Moustafa Abdel-Maksoud ◽  
Toni Skogström
Keyword(s):  
Model Tests ◽  
Roll Motion ◽  
Power Demand ◽  
Hull Form ◽  
Forced Roll ◽  
Ice Conditions ◽  
Level Ice ◽  
Metacentric Height ◽  
The Impact ◽  
Ice Resistance

Abstract Following the development of low friction hull coatings and azimuthing propulsion for icebreaking vessels, the development of auxiliary systems for reducing ice resistance fell from focus of research. One of these systems is comprised of active heeling tanks which induce a forced roll motion on the icebreaker. Today it is not fully understood how effective or even useful such systems would be for the icebreaking performance in combination with a modern icebreaking hull form. In this study, the impact of active heeling systems on level ice resistance is investigated by performing ice model tests with an icebreaker representing the latest design generation. The level ice thickness used in the model tests corresponds to the maximum continuous icebreaking capability of the evaluated vessel in multi-year ice conditions. Additionally, a calculation method is developed to predict the impact of forced roll motion on the ice resistance. The calculated prediction is evaluated against the model-scale data. Finally, the effectiveness of the active heeling system is evaluated from an engineering perspective: does the active heeling system reduce the power demand, or would the same result be achievable by increasing the propulsion power accordingly. It was found that the roll motion impacts the ice resistance in level ice. The main influence in this regard lies with the tank volume and metacentric height of the icebreaker. Additionally, it was observed that an optimum heel angle dependent on the ice condition can be determined which is not necessarily the highest one achievable. The case study predicts a reduced power demand for a modern icebreaker hull form in harsh ice conditions.

DP Ice Model Test of Arctic Drillship and Polar Research Vessel

2012 ◽  
Author(s):  
Torbjørn Hals ◽  
Nils Albert Jenssen
Keyword(s):  
Numerical Models ◽  
Offshore Structures ◽  
Model Tests ◽  
Full Scale ◽  
The Arctic ◽  
Research Vessel ◽  
Station Keeping ◽  
Ice Drift ◽  
Ice Conditions ◽  
Ice Model

The paper presents the results from a series of ice model tests performed as part of the DYPIC (Dynamic Positioning in Ice Conditions) research program. DYPIC is a research and development project within the EU’s ERA NET MARTEC project. The major purpose of the DYPIC project is development of equipment and methods for DP Ice Model testing which allows the prediction of station keeping capability of different vessel types and offshore structures under various ice conditions. The first DYPIC model tests performed in 2011 was conducted with two significantly different vessel sizes, a 68.0000 m3 volume displacement arctic drillship and an 8.600 m3 polar research vessel. The model scale was 1/30 for the arctic drillship and 1/18.6 for the Polar Research Vessel. The model tests were performed in the ice model basin at HSVA using vessel models equipped with thruster capacity similar to full scale operation according to DP class 2 / 3 operations. The DP control system was also modified from normal open water DP operations in order to cope with the highly varying ice drift loads acting on the vessel. The test program gave data supporting the development of numerical models of ice loads from managed ice, see reference [6]. The main focus in this paper is on the station keeping performance and associated thrust utilization as a function of varying ice drift loads. The results and data collected in the first year of the DYPIC program demonstrates that DP ice model tests will be a valuable tool for evaluation of vessel performance prior to moving on to full scale arctic DP operations.

Semi-Empirical Crest Distributions of Long-Crest Nonlinear Waves of Three-Hour Duration

2017 ◽  
Author(s):  
Zhenjia (Jerry) Huang ◽  
Qiuchen Guo
Keyword(s):  
Nonlinear Wave ◽  
Wave Height ◽  
Model Test ◽  
Significant Wave Height ◽  
Spectral Peak ◽  
Wave Crest ◽  
Empirical Formulas ◽  
Peak Period ◽  
Significant Wave ◽  
Semi Empirical

In wave basin model test of an offshore structure, waves that represent the given sea states have to be generated, qualified and accepted for the model test. For seakeeping and stationkeeping model tests, we normally accept waves in wave calibration tests if the significant wave height, spectral peak period and spectrum match the specified target values. However, for model tests where the responses depend highly on the local wave motions (wave elevation and kinematics) such as wave impact, green water impact on deck and air gap tests, additional qualification checks may be required. For instance, we may need to check wave crest probability distributions to avoid unrealistic wave crest in the test. To date, acceptance criteria of wave crest distribution calibration tests of large and steep waves of three-hour duration (full scale) have not been established. The purpose of the work presented in the paper is to provide a semi-empirical nonlinear wave crest distribution of three-hour duration for practical use, i.e. as an acceptance criterion for wave calibration tests. The semi-empirical formulas proposed in this paper were developed through regression analysis of a large number of fully nonlinear wave crest distributions. Wave time series from potential flow simulations, computational fluid dynamics (CFD) simulations and model test results were used to establish the probability distribution. The wave simulations were performed for three-hour duration assuming that they were long-crested. The sea states are assumed to be represented by JONSWAP spectrum, where a wide range of significant wave height, peak period, spectral peak parameter, and water depth were considered. Coefficients of the proposed semi-empirical formulas, comparisons among crest distributions from wave calibration tests, numerical simulations and the semi-empirical formulas are presented in this paper.

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