Ice Resistance Research Articles

Ice Resistance Assessment for a Large Size Vessel Running in a Narrow Ice Channel Behind an Icebreaker

Ice Resistance Assessment for a Large Size Vessel Running in a Narrow Ice Channel Behind an Icebreaker

Research on ice resistance of an icebreaker during continuous icebreaking

Objective In order to accurately assess the ice resistance experienced by the icebreaker during continuous icebreaking while sailing in the level ice zone, and to understand the characteristics of different forecasting methods, this paper uses empirical formula method, numerical simulation method and ship model test method to evaluate the icebreaker's continuous sailing in smooth ice. The ice resistance was predicted. Method In this paper, the nonlinear finite element software DYNA is used to construct ice numerical simulation models based on traditional finite element and cohesive element methods, respectively, to simulate the bending fracture and the interaction process that occurs when the level ice interacts with the icebreaker. At the same time, using the empirical formula method, three different empirical formulas were used to calculate the ice resistance, and the sensitivity analysis of the parameters affecting the prediction results of the empirical formula method was also carried out. Results The study found that ice resistance showed an upward trend with the increase of speed, ice thickness and bending strength. Among them, ice thickness has the greatest influence on ice resistance. Among the three empirical formulas, the prediction results of the Lindqvist formula are closer to the ship model test results, while the Vance and Lewis formulas are more conservative. Traditional finite element and cohesive element methods have more accurate ice resistance prediction results when the thickness is small. When the ice thickness is large, the error is about 25%. In the case of low ice thickness and high speed, the ice resistance value predicted by the cohesive element method is more accurate than the traditional finite element method, and the accuracy error is within 10% compared with the ship model test result. Conclusion In the actual ice resistance forecast, the empirical formula method and numerical simulation method can be combined to take into account the accuracy and efficiency of the forecast results, which has certain engineering application significance.

Ice-breaking performance sensitivity of the polar icebreaker to structure, control and ice parameters under different prediction models

Ice-breaking processes of an icebreaker are complex and many numerical models are proposed to predict the ice-breaking performance. Under the same polar conditions, different prediction models may derive different ice-breaking performances. Hence, it is necessary to analyze the influences of different prediction models and their corresponding input factors on the ice-breaking performance. However, there is almost no relevant study on such issues and it is urgent to fill this gap. In this study, different prediction models of the ice resistance are compared and analyzed. Subsequently, a global sensitivity analysis (SA) of the ice-breaking performance is performed for key input factors including structure, control, and ice parameters. Results show that the same input factors have appreciably different influences on the ice-breaking performance between different models. Besides, a global sensitivity of the maximized ice-breaking performance to structure parameters is analyzed, finding that the ship width is the most decisive factor. Impacts of different prediction models on the maximized ice-breaking performance regarding control parameters are also studied. Results indicate that model selection greatly influences the optimal performance and controls. Finally, an SA-based design process for the icebreaker is established, which can help perform the design work in a relatively efficient and economical way.

Ship resistance when operating in floating ice floes: Derivation, validation, and application of an empirical equation

With the effects of global warming, the Arctic is presenting a new environment where numerous ice floes are floating on the open sea surface. Whilst this has improved Arctic shipping navigability in an unprecedented way, the interaction of such floes with ships is yet to be understood to aid the designing of ships and route planning for this region. To further explore this topic, the present work develops a procedure to derive an empirical equation that can predict the effects of such floes on ship resistance. Based on a validated computational approach, extensive data are extracted from simulations of three different ships with varying operational and environmental conditions. The ice-floe resistance is shown to strongly correlate with ship beam, ship buttock angle, ship waterline angle, ship speed, ice concentration, ice thickness and floe diameter, and the regression powers of each of the parameters on resistance are ascertained. This leads to a generic empirical equation that can swiftly predict ice-floe resistance for a given ship in a given condition. Subsequently, demonstrations are given on the incorporation of the derived equation into a set of real-time Arctic ship performance model and voyage planning tool, which can predict a ship's fuel consumption in ice-infested seas and dynamically suggest a route with the least safety concern and fuel consumption. Moreover, the equation is validated by providing ice resistance prediction for experimental and full-scale conditions from multiple sources, showing high accuracy. In conclusion, the empirical equation is shown to give valid and rapid estimates for ice-floe resistance, providing valuable insights into ship designs for the region, as well as facilitating practical applications for polar navigation.

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

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.

빙마찰계수에 따른 쇄빙탱커의 빙저항 변화

This study describes the model tests in ice according to the frictional coefficient of an ice-breaking ship and the change in ice resistance by the analysis method for each component of ice resistances. The target vessel is a 90K DWT ice-breaking tanker capable of operating in ARC7 ice conditions in the Arctic Ocean, and twin POD propellers are fitted. The hull was specially painted with four different frictional coefficients on the same ship model. The total ice resistance can be separated by ice breaking, ice buoyancy, ice clearing resistances through the tests in level ice, pre-sawn ice and creep test in pre-sawn ice under sea ice thickness of 1.2 m and 1.7 m. Ice resistance was analyzed by correcting the thickness and bending strength of model ice by the ITTC correction method. As the frictional coefficient between the hull and ice increases, ice buoyancy and clearing resistances increase significantly. When the surface of the hull is rough, it is considered that the broken ice pieces do not slip easily to the side, resulting in an increase in ice buoyancy resistance. Also, the frictional coefficient was found to have a great influence on the ice clearing resistance as the ice thickness became thicker.

Probabilistic estimation of level ice resistance on ships based on sea ice properties measured along summer Arctic cruise paths

The decline of Arctic sea ice makes trans-Arctic transport possible in the summer, which increases the requirement of ice-strengthened vessels. Accurate estimation of ice resistance is necessary for ice-strengthened ship design and this process requires data on various ice properties. The objective of this study was to investigate the probabilistic characteristics of Arctic sea ice properties associated with estimations of ice resistance on ships. To achieve this aim, measurements of ice properties were collected from Arctic voyages conducted in the summers of 2008−2016. Ice thickness and ice concentration were observed along ship routes, and ice flexural strength and effective modulus were determined based on the physical properties of ice. The ice–hull kinetic friction coefficient was estimated according to ship velocity. Statistical analyses were conducted on these ice properties. The results showed that most ice properties can be described using existing statistical models (Burr XII, Beta, Gamma, and generalized extreme value distributions), with the exceptions of ice concentration, ice salinity and temperature, as well as friction coefficient. Furthermore, a Monte Carlo simulation was employed to estimate the ice resistance of a ship moving forward in a level ice zone based on a well-established empirical equation. The results showed that the distribution of ice resistance conformed to a Gamma distribution. The correlation coefficients between ice density and flexural strength as well as effective modulus had negligible effects on the simulation results. This study provides a helpful guide for the design of ice-strengthened ships and related numerical simulations required for summer trans-Arctic navigation.

A comparison of two ship performance models against full-scale measurements on a cargo ship on the Northern Sea Route

ABSTRACT The present paper introduces the development and verification of two ship performance models which have been implemented in a voyage planning tool designed for summer Arctic operations of commercial vessels. A novel ice resistance estimation algorithm for ice-floe conditions is implemented in the ship performance models. The fuel consumption predicted using both of the models are compared against full-scale measurements collected on a cargo ship of lower ice-class on the Northern Sea Route. This work found that both models meet the purpose of estimating ship fuel consumption for such a voyage planning tool and identified directions for future efforts. In addition, the typical transit scenarios in summer Arctic conditions presented in this study prove that a voyage planning tool with viable ship performance models facilitates Arctic shipping in a safe and sustainable way.

GPU-Based DEM Simulations of Global Ice Resistance on Ship Hull During Navigation in Level Ice

The ice resistance on a ship hull affects the safety of the hull structure and the ship maneuvering performance in ice-covered regions. In this paper, the discrete element method (DEM) is adopted to simulate the interaction between level ice and ship hull. The level ice is modeled with 3D bonded spherical elements considering the buoyancy and drag force of the water. The parallel bonding approach and the de-bonding criterion are adopted to model the freezing and breakage of level ice. The ship hull is constructed with rigid triangle elements. To improve computational efficiency, the GPU-based parallel computational algorithm was developed for the DEM simulations. During the interaction between the ship hull and level ice, the ice cover is broken into small blocks when the inter-particle stress approaches the bonding strength. The global ice resistance on the hull is calculated through the contacts between ice elements and hull elements during the navigation process. The influences of the ice thickness and navigation speed on the dynamic ice force are analyzed considering the breakage mechanism of ice cover. The Lindqvist and Riska formulas for the determination of ice resistance on ship hull are employed to validate the DEM simulation. The comparison of results of DEM, Lindqvist, and Riska formula show that the DEM result is between those the Lindqvist formula and Riska formula. Therefore the proposed DEM is an effective approach to determine the ice resistance on the ship hull. This work can be aided in the hull structure design and the navigation operation in ice-covered fields.

Turbulence Structure and Momentum Exchange in Compound Channel Flows With Shore Ice Covered on the Floodplains

AbstractIce cover formed on a river surface is a common natural phenomenon during the winter season in cold high latitude northern regions. For the ice‐covered river with compound cross‐section, the interaction of the turbulence caused by the ice cover and the channel bed bottom affects the transverse mass and momentum exchange between the main channel and floodplains. In this study, laboratory experiments are performed to investigate the turbulent flow of a compound channel with shore ice covered on the floodplains. Results show that the shore ice resistance restricts the development of the water flow and creates a relatively strong shear layer near the edge of the ice‐covered floodplain. The mean streamwise velocity in the main channel and on the ice‐covered floodplains shows an opposite variation pattern along with the longitudinal distance and finally reaches the longitudinal uniformity. The mixing layer bounded by the velocity inflection point consists of two layers that evolve downstream to their respective fully developed states. The velocity inflection point and strong transverse shear near the interface in the fully developed profile generate the Kelvin‐Helmholtz instability and horizontal coherent vortices. These coherent vortices induce quasi‐periodic velocity oscillations, while the dominant frequency of the vortical energy is determined through the power spectral analysis. Subsequently, quadrant analysis is used in ascertaining the mechanism for the lateral momentum exchange, which exhibits the governing contributions of sweeps and ejections within the vortex center. Finally, an eddy viscosity model is presented to investigate the transverse momentum exchange. The presented model is well validated through comparison with measurements, whereas the constants α and β appeared in the model need to be further investigated.

Experimental investigations on the level ice resistance of ships with non-typical icebreaking bow shapes

ABSTRACT For non-typical icebreaking ships with high stem and/or small waterline angles, 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 ships with non-typical icebreaking bow shapes, a methodology to improve the principal understanding of the hull–ice interaction process, ice failure, level ice resistance and its distribution along the ship hull during model scale ice tests is developed. For this purpose, one ship model has been manufactured and extensively instrumented. By performing resistance tests at several loading conditions, in model ice sheets of different thickness and at multiple speed values, relevant information on the nature of ice resistance of such ship type can be obtained. In this paper, the methodology is briefly summarized and part of the results of the model testing campaign are presented and discussed.

A method for assessing ship operability in dynamic ice for independent navigation and escort operations

Ships navigating in ice inevitably encounter different ice conditions. Dynamic ice typically presents severe conditions when it is moving perpendicular towards the parallel midship section, which can lead to ships getting stuck in ice. This can cause delays for ships or even damage to the ship hull. However, there currently is no model to assess ship operability in this dynamic ice. This paper aims to develop a method to assess operability of ships in dynamic ice conditions, which can be used for ship routing to avoid ship stuck. The method is especially useful for emergency response planning purposes, e.g. for marine pollution preparedness and response planning, where an understanding of the operability of response vessels in dynamic ice conditions currently is lacking. First, a transit model is introduced for both independent navigation and escort operations, considering the additional ice resistance by dynamic ice. Then, a ship operability index is proposed based on the modelling of ship's performance. Case studies of independent navigation and escort operations in realistic dynamic ice conditions are investigated to compare with the simulated results. Reasonable agreement is obtained, indicating that the proposed method can be used for ship operability assessment in dynamic ice.

A numerical solver for coupled dynamic simulation of glacial ice impacts considering hydrodynamic-ice-structure interaction

Glacial ice features pose great threats on the safety of ships and offshore structures in the arctic. House sized bergy bits or growlers are of particular concern because of the detection capability limits of marine radars. Analysis and design of structures against collisions from such glacial ice bodies has always been challenging due to the complicated hydrodynamic-ice-structure interaction.This paper proposes a numerical solver for coupled simulation of glacial ice impacts accounting for the effects of hydrodynamic-ice-structure interaction. The solver adopts user subroutines provided in LS-DYNA and combines three different modules, i.e. the BWH (Bressan-Williams-Hill) criterion for the prediction of fracture of steels, a hydrostatic pressure dependent plasticity-based material model for constitutive modelling of ice, and the linear potential flow theory for hydrodynamic loads.The proposed solver is verified and calibrated to ice resistance data from field tests and is then applied to simulate ice collisions on a semi-submersible platform column. Collision scenarios with both in-plane 3DOF and full 6DOF ice motions are considered. The results are discussed with respect to ice motion trajectories, ice crushing and structural damage under the combined action of ice indentation and sliding loads. The dissipated energy predicted by external dynamic models is compared with simulation results and discussed.

Investigation of model-scale brash ice properties

A brash ice channel is a typical operation condition for ice-going commercial vessels. The Finnish-Swedish Ice Class Rules (FSICR) define the vessels ice class performance requirements particularly in a brash ice channel. The vessel performance can be verified using model tests, which are conducted according to the FSICR guidelines. However, the guidelines define mainly the channel thickness and width. This research examined, which other brash ice parameters influence the brash ice behavior around a ship hull. The study focuses on the brash ice as a material. Based on literature review of earlier research, the author focused on five central parameters: porosity, piece size and distribution, angle of repose, compressibility, and angle of internal friction. These parameters were examined in three different model brash ice types. The results show that different brash ice types have different properties covering all the five investigated parameters. This variation in brash ice properties presumably affect the behavior of brash ice mass around a moving ship hull and the vessel resistance in brash ice indicating a need for better model brash ice standardization to secure consistent channel model test results.

Experimental Studies of the Resistance of Transport Ships at Moving in Composite Broken Ice

Arctic ships move in broken ice most of the time. Therefore, forecasting the ice performance of ships when moving in a channel behind an icebreaker or in natural broken ice is relevant at the design stage. For this, theoretical and experimental studies of the movement of various models of ships in a small experimental basin were carried out. The process of modeling and testing of models of active ice navigation ships in a composite ice model is described. Test results and formulas for assessing ice resistance are given. They are derived from the analysis of model tests. Conclusions about the possibility of carrying out and obtaining reliable results of the experiment in small experimental pools are made. The resistance when moving ships in a wide ice channel does not differ from the resistance when moving ships in a field of broken ice. The jamming of ice floes between the edges of the channel and the side occurs when ships move in a narrow channel. Consequently, the “buffering effect” occurs and the resistance increases significantly.

The Screening Influence of the Composite Structure Broken Ice on the Gravity Waves Propagation

The broken ice influence on the surface of the water area on the parameters of propagation of gravity waves including ship waves is considered. The discrepancy using of the superposition principle, which consist in the addition of the independent component of water and ice resistance of the vessels motion and used in the existing analytical calculations, and the real process picture is shown. The quantitative assessment of the broken ice influence on the resistance components is given.

Quenchability improvement and control simplification by ice mandrel in hot stamping of ultra-high strength steel hollow parts

Abstract To produce ultra-high strength steel hollow parts for reducing the body weight and improving the collision safety of automobiles, a hot stamping process of quenchable steel tubes using ice mandrel and resistance heating was developed. To solve the problem of buckling and low cooling rate during stamping of hollow products, an ice mandrel was inserted in the tube. The effect of the ice mandrel on heating and forming behavior was investigated. Quenchable ice-filled steel tubes were able to heat over austenitizing temperature by adding papers as thermal insulation. Moreover, the ice mandrel simplifies the controlling process by generating a reaction force to prevent the buckling and increase the hardness after die quenching of the ice-filled tubes. Using the ice mandrel with insulating papers is significantly effective to produce ultra-high strength hollow products.

Strategy on choice of layback spins in figure skating

Spin is an important component of figure skating, one of the most elegant events in the Winter Olympic Games. It is always presented as an example of the conservation of angular momentum in mechanics textbooks. However, the physics behind it in the actual operation is not that simple. Herein, we analyzed videos of an elite figure skater with open source video analysis. The moments of inertia of her body in six different layback positions were obtained. The average ice resistance during her spin was found to be about 26N and was put into consideration in the following calculation. Twenty-two different layback spins that score the same basic value were discussed. The initial angular momentum a skater needs when executing a spin is considered to be the largest contributor to its difficulty; the suggested easiest spin among the 22 was thus found by comparing their initial angular momentum. This paper presents a strategy that may help figure skaters achieve a high-scored layback spin efficiently, and the process itself will be an inspiring example of applying theory to practice for physics students.

Оценка эффективности разработанного защитного покрытия для металлоконструкций с повышенной коррозионной стойкостью и устойчивостью к обледенению

Оценка эффективности разработанного защитного покрытия для металлоконструкций с повышенной коррозионной стойкостью и устойчивостью к обледенению

The Calculation Method of Ice Resistance in Level Ice by the Ice-Covered Hull Model

The Calculation Method of Ice Resistance in Level Ice by the Ice-Covered Hull Model