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.

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.

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

2021 ◽  
Author(s):  
Johanna Marie Daniel ◽  
Tuomas Romu ◽  
Franz Von Bock Und Polach ◽  
Moustafa Abdel-Maksoud ◽  
Toni Skogstr\xf6m
Keyword(s):  
Roll Motion ◽  
Forced Roll ◽  
Ice Resistance

A Review of Research to Aid the Development of Commercial Arctic Marine Transportation: 1982 Trafficability Tests on the USCGC Polar Star

1985 ◽  
Vol 22 (01) ◽  
pp. 28-35
Author(s):  
Seibold Frederick
Keyword(s):  
Ice Cores ◽  
Coast Guard ◽  
The Arctic ◽  
Marine Transportation ◽  
Newport News ◽  
Research Activities ◽  
Ice Conditions ◽  
Level Ice ◽  
Ice Resistance ◽  
Resistance Tests

A multi-year "trafficability" research program was begun in 1978 to demonstrate that year-round commercial marine transportation in Arctic waters is feasible and to collect data necessary to begin developing the criteria to design and operate marine vehicles for that environment. Using U.S. Coast Guard Polar Class icebreakers, annual winter deployments had been made in 1979, 1980, and 1981 into the Bering and Chukchi Seas to collect environmental and ship performance data. Early in 1982, the fourth phase of these research activities was conducted on the USCGC Polar Star in western Alaskan waters as far north as the Arctic Circle. Participants in the research were the Maritime Administration, the U.S. Coast Guard, the State of Alaska, the Canadian Ministry of Transport, twelve participating companies of the Alaskan Oil and Gas Association, and the Newport News Shipbuilding Company. This paper reviews the results of this voyage and the data collected. The Polar Star was instrumented to continuously monitor and record propulsion and ship motion parameters and speed. Video recording equipment was used to document ice conditions. Extensive on-ice equipment was used to profile ice features and to measure other ice parameters. Numerous pressure ridges were profiled and ice cores taken to improve the understanding of Bering and Chukchi Sea winter ice conditions and ice strength. Level ice resistance tests were conducted. However, heavy level ice conditions were not encountered and it is planned to complete the level ice resistance tests in 1984. Other research tasks included an ice edge analysis, hull friction experiments, and an ice drift study.

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.

Numerical Methods for the Prediction of the Bilge Keel Effects on the Response of Ship-Shaped Hulls

2007 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Yi-Hsiang Yu ◽  
Vimal Vinayan
Keyword(s):  
Numerical Scheme ◽  
Hydrodynamic Interaction ◽  
Roll Motion ◽  
Length Scale ◽  
Hull Form ◽  
Longitudinal Length ◽  
Forced Roll ◽  
Hull Forms ◽  
Volume Method ◽  
Bilge Keel

This paper addresses the hydrodynamic interaction and response of typical FPSO/FSO and LNG hull-forms with bilge keels. The hull-forms are assumed to be slender with the longitudinal length-scale exceeding the other two physical dimensions. This assumption allows the modeling of the flow around the hull-form in a 2-D strip-wise manner. A Finite Volume Method (FVM) based numerical model is developed to analyze the flow around the 2-D hull-sections, with and without bilge keels. The effect of the bilge keels in the damping of hull motions is presented with the application of the numerical scheme to a hull in forced roll motion, and its transient response in roll and heave decay.

Development of Hull Forms for a 190,000 DWT Icebreaking Ore Carrier

2011 ◽  
Author(s):  
Kyung Duk Park ◽  
Yong Kwan Chung ◽  
Young Sik Jang ◽  
Hyun Soo Kim ◽  
David Molyneux
Keyword(s):  
Open Water ◽  
Bulk Carrier ◽  
Hull Form ◽  
Model Experiments ◽  
Pack Ice ◽  
Ice Conditions ◽  
Level Ice ◽  
Fast Ice ◽  
Improved Performance ◽  
Hull Forms

This paper describes the development of three candidate hull forms for 190,000 DWT ore carrier for operation in ice covered water. It builds on Hyundai Heavy Industries expertise in ore carrier design, and discusses some of the changes required for operation in heavy ice conditions. The overall concept was to have a target speed of 6 knots in land fast ice 1.7m thick and 15 knots in open water. Three candidate bow shapes were designed and analyzed, based on a common stern arrangement. The development of the hull form included three methods of predicting the performance of the ships in ice. Empirical analysis was carried out for all three hulls, based on experience gained from model experiments on bulk carrier hull forms in ice. Numerical analysis was carried out on all three bow shapes using a computer program (based on the discrete element method) to simulate the interaction between the ship and the ice. Physical model experiments were carried out for resistance and propulsion in level ice, pack ice and ridges on the selected design. As a result of the model experiments, the selected bow shape was modified to reduce its resistance in ice. The improved performance of the modified hull was confirmed with additional numerical simulations.

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.

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.

Parametric Roll of High Speed Ships in Regular Waves

2013 ◽  
Author(s):  
Hisham Moideen ◽  
Abhilash Somayajula ◽  
Jeffrey M. Falzarano
Keyword(s):  
Time Domain ◽  
High Speed ◽  
Mathieu Equation ◽  
Analytical Models ◽  
Roll Motion ◽  
Regular Waves ◽  
Parametric Roll ◽  
Hull Form ◽  
Linear Damping ◽  
Metacentric Height

Analysis of ship parametric roll has generally been restricted to simple analytical models and sophisticated time domain simulations. Simple analytical models do not capture all the critical dynamics while time-domain simulations are often time consuming to implement. The model presented in this paper captures the essential dynamics of the system without over simplification. This work incorporates various important aspects of the system and assesses the significance of including or ignoring these aspects. Special consideration is given to the fact that a hull form asymmetric about the design waterline would not lead to a perfectly harmonic variation in metacentric height. Many of the previous works on parametric roll make the assumption of linearized and harmonic behavior of the time-varying restoring arm or metacentric height. This assumption enables modeling the roll motion as a Mathieu equation. This paper provides a critical assessment of this assumption and suggests modeling the roll motion as a Hills equation. Also the effects of non-linear damping are included to evaluate its effect on the bounded parametric roll amplitude in a simplified manner.

scholarly journals Calculation Methods of Icebreaking Capability for a Double-Acting Polar Ship

2020 ◽  
Vol 8 (3) ◽  
pp. 179 ◽  
Author(s):  
Li Zhou ◽  
Feng Diao ◽  
Ming Song ◽  
Yue Han ◽  
Shifeng Ding
Keyword(s):  
Model Test ◽  
Dynamic Method ◽  
Model Tests ◽  
State Research ◽  
Dynamic Methods ◽  
Level Ice ◽  
Ice Resistance ◽  
Test Result ◽  
Good Agreement ◽  
Key Parameter

As a key parameter, icebreaking capability is often used to judge whether a polar ship could navigate in level ice at a certain speed. This paper presents two methods to calculate icebreaking capability. The first one is a static method based on the estimation of ice resistance under different ice thicknesses and ship speeds. The second is a dynamic method that involves solving the equation of motion. A series of model tests with a double-acting icebreaking tanker were also carried out in the ice basin of the Krylov State Research Center to measure ice resistances. The simulated ice resistances were compared with model tests results for both ahead and astern running operations. The calculated icebreaking capability based on static and dynamic methods was validated with the model test result. A good agreement was achieved between measurement and simulation. The discrepancy between the model test result and the result simulated by the static or dynamic method was minor.

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