Experimental and Theoretical Investigations on the Characteristics of Ice Floes Broken by Ships Sailing Ahead in Level Ice

2019 ◽  
Author(s):  
Daniela Myland
Keyword(s):  
Image Analysis ◽  
Research Effort ◽  
Analysis Procedure ◽  
Shape Parameters ◽  
Ship Model ◽  
Video Frames ◽  
Theoretical Investigations ◽  
Level Ice ◽  
Ice Floes ◽  
Ice Resistance

Abstract Although the hull shapes of modern ice breaking vessels seem to be quite similar at a first glance, there are significant differences in their ice breaking performance. A significant amount of research effort was spent on investigations of the icebreaking process and the resulting forces. However, little information is available on the correlations between ice floe characteristics, hull shape parameters, ice properties and the ice resistance. Thus, systematic model tests in level ice and pre-sawn ice with four icebreaking ship models of one ship type have been conducted to gain new insight on these correlations. During the tests in level ice under water video records have been taken from below the ship model. Video frames have been analyzed by application of a dedicated image analysis procedure which is mainly based on a number of semiautomatic scripts applied in Matlab®. Results of the analysis are presented and discussed within this paper.

Subsurface Ice Transport at a Transversally Towed Ship Model

2017 ◽  
Author(s):  
Li Zhou ◽  
Rüdiger U. Franz von Bock und Polach ◽  
Xu Bai
Keyword(s):  
Froude Number ◽  
Densimetric Froude Number ◽  
Ship Model ◽  
Drift Speed ◽  
Ice Accumulation ◽  
Underwater Cameras ◽  
Low Froude Number ◽  
Broken Ice ◽  
Level Ice ◽  
Ice Floes

The subsurface transport of ice along the underwater body of a ship hull or a structure may cause damages to appendages. In order to investigate the conditions under which the ice accumulation occurs, a series of model tests was carried out in the ice basin of Aalto University. The used ship model was towed laterally against the ice with one side breaking level ice. The transport of broken ice floes broken off from the intact ice sheet has been has been monitored with underwater cameras. Both the model drift speed, respectively the ice drift speed, and the ice thickness are found to affect ice accumulation process. The Densimetric Froude number is introduced as measured to determine whether ice floes will accumulate on the upstream of the hull. It is found that ice accumulation is triggered at relatively low Froude number.

Experimental Investigation of Aspects Influencing the Level Ice Resistance of Ships With Non-Typical Icebreaking Bow Shapes

2021 ◽  
Author(s):  
Daniela Myland ◽  
Quentin Hisette ◽  
Emre Cilkaya ◽  
Yusuf Sefa Özhan
Keyword(s):  
Ice Sheets ◽  
Relevant Information ◽  
Interaction Process ◽  
Total Resistance ◽  
Ship Model ◽  
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 operability of such non-typical hull shapes in level ice, a study has been carried out 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-axis 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 developed methodology and the analysis of the measured loads have been described in previous publications. As direct continuation, the present paper focuses on investigation of the ice floe characteristics and its linkage to the ice properties. Moreover, analysis results related to the crushing portion of the total resistance in ice, the friction between ice and ship model hull as well as the ship model motions during ice model testing are presented within the paper.

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.

scholarly journals An Approach to Determine Optimal Bow Configuration of Polar Ships under Combined Ice and Calm-Water Conditions

2021 ◽  
Vol 9 (6) ◽  
pp. 680
Author(s):  
Hui Li ◽  
Yan Feng ◽  
Muk Chen Ong ◽  
Xin Zhao ◽  
Li Zhou
Keyword(s):  
Numerical Simulation ◽  
Water Resistance ◽  
Numerical Technique ◽  
Experimental Studies ◽  
Resistance Index ◽  
Simulation Method ◽  
Present Approach ◽  
Calm Water ◽  
Level Ice ◽  
Ice Resistance

Selecting an optimal bow configuration is critical to the preliminary design of polar ships. This paper proposes an approach to determine the optimal bow of polar ships based on present numerical simulation and available published experimental studies. Unlike conventional methods, the present approach integrates both ice resistance and calm-water resistance with the navigating time. A numerical simulation method of an icebreaking vessel going straight ahead in level ice is developed using SPH (smoothed particle hydrodynamics) numerical technique of LS-DYNA. The present numerical results for the ice resistance in level ice are in satisfactory agreement with the available published experimental data. The bow configurations with superior icebreaking capability are obtained by analyzing the sensitivities due to the buttock angle γ, the frame angle β and the waterline angle α. The calm-water resistance is calculated using FVM (finite volume method). Finally, an overall resistance index devised from the ship resistance in ice/water weighted by their corresponding weighted navigation time is proposed. The present approach can be used for evaluating the integrated resistance performance of the polar ships operating in both a water route and ice route.

scholarly journals Formulation of Ice Resistance in Level Ice Using Double-Plates Superposition

2020 ◽  
Vol 8 (11) ◽  
pp. 870
Author(s):  
Liang Li ◽  
Qingfei Gao ◽  
Alexander Bekker ◽  
Hongzhe Dai
Keyword(s):  
Elastic Plate ◽  
Approximate Model ◽  
Ice Thickness ◽  
Full Scale Test ◽  
Ship Resistance ◽  
Bending Resistance ◽  
Level Ice ◽  
Scale Test ◽  
Coulomb Criterion ◽  
Ice Resistance

The estimation of ship resistance in ice is a fundamental area of research and poses a substantial challenge for the design and safe use of ships in ice-covered waters. In order to estimate the ice resistance with greater reliability, we develop in this paper an improved Lindqvist formulation for the estimation of bending resistance in level ice based on the superposition of double-plates. In the developed method, an approximate model of an ice sheet is firstly presented by idealizing ice sheeta as the combination of a semi-infinite elastic plate and an infinite one resting on an elastic foundation. The Mohr–Coulomb criterion is then introduced to determine the ice sheet’s failure. Finally, an improved Lindqvist formulation for estimation of ice resistance is proposed. The accuracy of the developed formulation is validated using full-scale test data of the ship KV Svalbard in Norway, testing the model as well as the numerical method. The effect of ice thickness, stem angle and breadth of bow on ship resistance is further investigated by means of the developed formulation.

Validation of a new image analysis procedure for quantifying filamentous bacteria in activated sludge

2014 ◽  
Vol 70 (6) ◽  
pp. 955-963 ◽  
Author(s):  
Ewa Liwarska-Bizukojc ◽  
Marcin Bizukojc ◽  
Olga Andrzejczak
Keyword(s):  
Image Processing ◽  
Image Analysis ◽  
Activated Sludge ◽  
Analysis Procedure ◽  
Automated Image Analysis ◽  
Filamentous Bacteria ◽  
Image Processing And Analysis ◽  
Manual Counting ◽  
Analysis Application ◽  
Activated Sludge Systems

Quantification of filamentous bacteria in activated sludge systems can be made by manual counting under a microscope or by the application of various automated image analysis procedures. The latter has been significantly developed in the last two decades. In this work a new method based upon automated image analysis techniques was elaborated and presented. It consisted of three stages: (a) Neisser staining, (b) grabbing of microscopic images, and (c) digital image processing and analysis. This automated image analysis procedure possessed the features of novelty. It simultaneously delivered data about aggregates and filaments in an individual calculation routine, which is seldom met in the procedures described in the literature so far. What is more important, the macroprogram performing image processing and calculation of morphological parameters was written in the same software which was used for grabbing of images. Previously published procedures required using two different types of software, one for image grabbing and another one for image processing and analysis. Application of this new procedure for the quantification of filamentous bacteria in the full-scale as well as laboratory activated sludge systems proved that it was simple, fast and delivered reliable results.

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