Icebreaking Capability Research Articles

Russia’s Arctic icebreaking capability: an assessment

ABSTRACT This paper explores the Russian icebreaker fleet capabilities, problems, and perspectives. It also analyses Russian civilian and military icebreakers, and their dual-use capabilities. The paper responds to a question grounded in Russia's Arctic policy: How critical is icebreaking capability to Russia’s Arctic strategy? Based on the findings, the paper concludes that the influences of climate change and Russia’s foreign and external security policy affect the development of its icebreaker fleet in the Arctic. In this respect, temperatures of the ice melting in the Arctic and delays in building new icebreakers, because of access to the technology caused by the sanctions, are stressed. On the other hand, Russia’s confrontation with the West following the invasion of Ukraine and the sanctions over it, increases the allocation of government finance to support local shipbuilding companies. Moreover, the paper argues that Russia’s economic difficulties and shipbuilding delays should enhance the dual-use capabilities of the Russian icebreakers in the coming years.

ANTI-ICING DEVICE OF AN ICEBREAKER AS A MEANS OF INCREASING THE SHIP ENERGY EFFICIENCY

An overview of using pneumatic pressurization systems of icebreaker hulls in order to increase their icebreaking capability and a description of traditional design solutions in the design of systems are presented in the paper. It is noted that the design of systems is based on the methods of analogy and similarity, taking into account the results of field tests. Theoretical methods of taking into account the design features of the icebreaker hull and the technical characteristics of its power plant when determining the required air supply, its parameters, and outlets location are currently insufficiently developed. It is shown that the improvement of anti-icing devices of icebreakers provides an increase in their energy efficiency. The main areas of pneumatic charging devices improvement is to reduce the cost of driving supercharging units and the possibility of using secondary energy resources of marine diesel engines for their drive. The calculations results of the power required for the drive of air blowers depending on the air supply, other factors determining the energy consumption of the air blower system are indicated. The results of the conducted research confirm the possibilities of improving the anti-icing devices of icebreakers in order to increase their energy efficiency. The proposed method makes it possible to determine the required power costs and assess the possibilities of covering them with secondary energy resources with improved air blower drives. The maximum increase in energy efficiency can be achieved by choosing rational air supply parameters, reasonable placement of air supply openings, taking into account the design features of the icebreaker hull and the use of secondary energy resources of the main and auxiliary elements of the icebreaker power plant.

Numerical simulation of ship maneuverability in level ice considering ice crushing failure

For polar ship operating in ice-covered areas, numerical prediction and relevant research on maneuverability are particularly important. In this paper, a numerical method considering circumferential crack fracture of level ice based on former research is applied to calculate ice load and predict motion of ship turning in level ice. The difference between bending failure and crushing failure are also taken into consideration during the turning simulation, meanwhile crushing failure pattern is validated with measured data. The turning performance of icebreaker AHTS/IB Tor Viking Ⅱ based on present method is analyzed and compared with full scale measurement. The simulated icebreaking capability of the ship is also validated with sea trials and previous work. The results show that good agreement is achieved and the accuracy of the numerical prediction is improved by including crushing failure into previous research.

Ice breaking by a high-speed water jet impact

Ice breaking has become one of the main problems faced by ships and other equipment operating in an ice-covered water region. New methods are always being pursued and studied to improve ice-breaking capabilities and efficiencies. Based on the strong damage capability, a high-speed water jet impact is proposed to be used to break an ice plate in contact with water. A series of experiments of water jet impacting ice were performed in a transparent water tank, where the water jets at tens of metres per second were generated by a home-made device and circular ice plates of various thicknesses and scales were produced in a cold room. The entire evolution of the water jet and ice was recorded by two high-speed cameras from the top and front views simultaneously. The focus was the responses of the ice plate, such as crack development and breakup, under the high-speed water jet loads, which involved compressible pressure ${P_1}$ and incompressible pressure ${P_2}$ . According to the main cause and crack development sequence, it was found that the damage of the ice could be roughly divided into five patterns. On this basis, the effects of water jet strength, ice thickness, ice plate size and boundary conditions were also investigated. Experiments validated the ice-breaking capability of the high-speed water jet, which could be a new auxiliary ice-breaking method in the future.

Scenario-based optimization design of icebreaking bow for polar navigation

Global warming and ice extent reduction in Arctic makes commercial shipping through Arctic waters be promising in the near future. The fuel consumption and emission from ships on the Arctic shipping routes, which mainly depends on the ship resistance, is key factor to determine if it is more cost-effective comparing to traditional shipping route. The shipping route in Arctic water include open water and ice-covered water areas. The polar ships traveling through Arctic water need to have ice-strengthened hull to have ice-breaking capability to proceed safely in ice-covered water. Usually the bow hull form with good ice-breaking capability have high resistance in open water, while the bow form with good open-water efficiency (such as bulbous bow) may not have ice-breaking capability. This paper is to develop a methodology for optimized hull form design so that the minimum overall resistance in open-water and ice-covered water can be achieved, while maintaining desired level of ice-breaking capability for considered shipping route with expected ice conditions. The methodology proposed in this paper is based on the ship's desired route with historic ice data to define its typical operation profile. For the test example of this methodology, based on the desired route, the historic ice data are extracted from public available data source to determine the sections of open-water and ice-covered water, as well as the ice-thickness distribution along the route. The ship's resistance in open-water is calculated based on Rankine source method, while the ice resistance is calculated by Lindqvist formula. The overall resistance is weight-averaged based on the route's sections of open-water and ice-covered water. The ice-breaking capability is measured by the ice loads giving by the IACS Polar UR, which serves as the constraint during the optimization process. The parametric model is established for the optimization process. With an ice-breaking bow base design, the optimized bow hull form is achieved on the specified shipping route with historic ice condition. The result shows that the overall resistance is reduced by 5.42% while maintaining enough ice-breaking capability for the considered sample ship. Discrete Element Method is used to verify the optimized hull form's ice-breaking performance compatible with original hull form. It is shown that the methodology developed in this paper can be generally applied to polar ship hull form design for different shipping route and ice conditions.

The Modeling and Optimal Control of a Hybrid Propulsion System for an Ice-Capable Tanker

_ With the effects of global warming, the North Sea Route has become an economic option for cargo transportation because of the shorter distance between East Asia and Europe. Generally, conventional mechanical propulsion systems installed in ice-capable tankers suffer from significant drawbacks because of poor fuel efficiency when sailing at low speed, therefore, advanced technologies have been applied such as diesel electric and nuclear-powered propulsion; however, drawbacks still exist. Hybrid propulsion is a more environmental-friendly, economical solution for ships with icebreaking capability, which can address the drawbacks in both diesel electric and nuclear power systems. In this paper, modeling of system components is presented and implemented in MATLAB Simulink. A primary control strategy is applied to the system to ensure system stability, and an advanced secondary strategy is developed and applied to the power sources to minimize fuel consumption. Given two scenarios, the simulation results of the hybrid propulsion system developed in this research and those of diesel electric propulsion systems with DC and AC distribution systems are compared and indicate that the hybrid system can offer up to 22.4% fuel savings over ice-loading condition, and 39.5% fuel reduction over the particular voyage of varying speed in open water is applied in this paper. Introduction In recent years, some sea routes that were previously blocked by ice have become increasingly accessible in the warmest months of the year due to the effects of global warming. Researchers have estimated that, by 2030, the percentage of Arctic shipping will have increased to 25% of cargo trade between Europe and Asia (Lasserre 2019). Northern Sea Route (NSR) shipping provides benefits for international trade, but challenges still exist. Increasing carbon emissions have seriously impacted the Arctic environment (Hassol & Corell 2006). Table 1 shows the total number of ships using Heavy Fuel Oil (HFO) in Arctic waters in 2015, and associated black carbon emissions, as published by the IMO (Comer et al. 2017). As it is shown, oil tankers made up just 4.5% of all ships entering Arctic waters but despite their low proportion, they were responsible for 17% of black carbon emissions. Thus, an environmentally friendly and fuel-efficient propulsion system to reduce these emissions from tankers trading in Arctic waters is required.

Revisiting Trans-Arctic Maritime Navigability in 2011–2016 from the Perspective of Sea Ice Thickness

Arctic navigation has become operational in recent decades with the decline in summer sea ice. To assess the navigability of trans-Arctic passages, combined model and satellite sea ice thickness (CMST) data covering both freezing seasons and melting seasons are integrated with the Arctic Transportation Accessibility Model (ATAM). The trans-Arctic navigation window and transit time are thereby obtained daily from modeled sea ice fields constrained by satellite observations. Our results indicate that the poorest navigability conditions for the maritime Arctic occurred in 2013 and 2014, particularly in the Northwest Passage (NWP) with sea ice blockage. The NWP has generally exhibited less favorable navigation conditions and shorter navigable windows than the Northern Sea Route (NSR). For instance, in 2013, Open Water (OW) vessels that can only safely resist ice with a thickness under 15 cm had navigation windows of 47 days along the NSR (45% shorter than the 2011–2016 mean) and only 13 days along the NWP (80% shorter than the 2011–2016 mean). The longest navigation windows were in 2011 and 2015, with lengths of 103 and 107 days, respectively. The minimum transit time occurred in 2012, when more northward routes were accessible, especially in the Laptev Sea and East Siberian Sea with the sea ice edge retreated. The longest navigation windows for Polar Class 6 (PC6) vessels with a resistance to ice thickness up to 120 cm reached more than 200 days. PC6 vessels cost less transit time and exhibit less fluctuation in their navigation windows compared with OW vessels because of their ice-breaking capability. Finally, we found that restricted navigation along the NSR in 2013 and 2014 was related to the shorter periods of navigable days in the East Siberian Sea and Vilkitskogo Strait, with local blockages of thick ice having a disproportionate impact on the total transit. Shorter than usual navigable windows in the Canadian Arctic Archipelago and Beaufort Sea shortened the windows for entire routes of the NWP in 2013 and 2014.

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.

SMART with trans-critical CO2 power conversion system for maritime propulsion in Northern Sea Route, part 2: Transient analysis

To utilize the Northern Sea Route as a future commercial maritime transport route, a container ship with nuclear power and icebreaking capability was considered as an alternative to fossil fuel engines due to better reliability and reduce greenhouse gas emission. SMART was selected due to the possibility of near-term deployment and a high degree of safety, and a trans-critical CO2 cycle was considered for its power conversion system because of its expected good performance under the selected sailing environment. In part 1, major components and passive systems were designed based on thermodynamic cycle optimization. In part 2, GAMMA + code is modified to simulate CO2 two-phase flow, and the code is validated with experimental data. SMART with trans-critical CO2 cycle is modeled with the modified GAMMA + code to check the controllability of the system under icebreaking conditions, and evaluate safety after an accident event with CO2 Passive Residual Heat Removal System (PRHRS), using a natural circulation loop.

SMART with Trans-Critical CO2 power conversion system for maritime propulsion in Northern Sea Route, part 1: System design

The Northern Sea Route is a new way to connect Asia and Europe. To utilize the sea route, merchant ships are required to have the icebreaking capability. Since conventional fossil fuel engines have limitations for the icebreaking merchant ship propulsion, nuclear power having a long refueling period for icebreaking merchant ship is proposed in this paper. To evaluate the technical feasibility of the nuclear power for the icebreaking ship’s engine, 330MWth SMART is selected for the reference reactor core. The power conversion system for the SMART core is substituted with the trans-critical CO2 recompression cycle that has advantageous in low-temperature heat sink as in Northern Sea Route and low-temperature heat source, Pressurized Water Reactor operating conditions. In this paper, the major components of the trans-critical CO2 cycle are designed. Then, CO2 PRHRS, which is driven by CO2 natural circulation loop, is designed to substitute steam-water based PRHRS.

Experimental study on interaction, shock wave emission and ice breaking of two collapsing bubbles

In this work ice breaking caused by a pair of interacting collapsing bubbles was studied by an experimental approach. The bubbles were generated by an underwater electric discharge simultaneously, positioned either horizontally or vertically below a floating ice plate and observed via high-speed photography. The bubble-induced shock waves, which turn out to be crucial to the fracturing of the ice, were visualized using a shadowgraph method and also measured using pressure transduces. Unique bubble behaviour was observed, including bubble coalescence, bubble splitting, inclined counter-jets and asymmetric toroidal bubble collapse. Bubble dynamic properties, such as jet speed, jet energy and bubble centre displacement, were measured. Shock wave emission and ice breaking capability of the two bubbles were investigated over a range of inter-bubble and bubble–boundary distances. Regions where the damaging potential of the bubble pair are strengthened or weakened were summarized and possible reasons for the variation in the ice breaking capability were analysed based on bubble morphology, jet characteristics and shock wave pressure. The findings may contribute to more efficient ice breaking and also inspire new ways to manipulate cavitation bubble damage.

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

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.

Discrete element modelling of relationship between ice breaking length and ice load on conical structure

Conical structures are widely used in marine engineering in ice-covered area because of their icebreaking capability. The ice loads acting on the conical structures are closely related to the failure modes of sea ice. The discrete element method (DEM) is adopted to simulate the ice failure modes and ice loads during the interaction between sea ice and conical structure. In this study, the accuracy of DEM simulations is validated by comparing the simulated ice loads with the measured ice loads from the model tests in Hamburg Ship Model Basin (HSVA). A bending failure occurs when the sea ice interacts on the conical structure, and the sea ice breaks into many fragments with different breaking lengths. The influence of ice thickness, ice velocity, cone diameter at waterline and cone angle are considered to analyze the characteristics of ice breaking length. The simulation results show that the ice breaking length increases with the increase of ice thickness. The increase of ice velocity and cone diameter can lead to the change of sea ice failure mode, which can reduce the breaking length of sea ice and increase the ice load. The decrease of ice breaking length indicates that the failure mode of sea ice changes from the bending failure to the crushing failure. A static ice force formula considering the effect of ice breaking length can be proposed to predict the ice load of the structure and verify the reliability of the structure.

Method on continuous ice-breaking capability assessment of icebreaker

The opening of the Ice Silk Road is a great significant for the realization of the close connection with the European, and it is a promotion for China’s economic development. The icebreaker will play an important role in the Arctic strategy. More accurate ice load calculation and prediction of ice breaking capacity methods will provide important technical support for the design and construction of icebreaker. This paper aims to solve the above problems and carry out the following research work. The ice load in continuous icebreaking type is calculated in 3D numerical method. Then, the motion differential equation in time history is established to calculate the motion response. In addition, the structure strength under ice breaking condition is evaluated based on FEM. At last, the evaluation method of continuous ice breaking capacity is proposed in this paper. Compared with the results of literature, the accuracy of the ice load calculated by this method meets the requirements and could further guide the design and development of ice breaking vessels.

The comparative analysis of the methods of calculating the icebreaking capability of icebreakers

The comparative analysis of the methods of calculating the icebreaking capability of icebreakers

Numerical assessment of a double-acting offshore vessel's performance in level ice with experimental comparison

In this paper a numerical model is used to investigate the level ice performance of a double-acting intervention vessel, and the results are compared with a limited set of experimental data. The icebreaking capability and maneuverability in level ice are analyzed by evaluating the behavior of the vessel when it is running both ahead and astern. The simulated icebreaking patterns, h–v curves, and turning circles in different modes of operation are discussed and compared partly with the corresponding ice model tests. The simulation results can supplement the experimental data by providing more information about the vessel's maneuverability in level ice and identifying the physical foundation for the exhibited performance of the vessel. The paper also presents the implementation of a random crack size model for more realistic icebreaking behavior, giving more consistent evaluation of the ship's performance in various ice conditions.

B. Vessel Source Pollution

The new Chapter 4 of MARPOL Annex VI entered into force on 1 January, which includes requirements mandating the Energy Efficiency Design Index (EEDI) for new ships and the Ship Energy Efficiency Management Plan for all ships (see last year’s report). The Marine Environment Protection Committee (MEPC) held its sixty-fifth session (MEPC-65) on 13–17 May. MEPC-65 approved amendments to MARPOL Annex VI with a view to adoption next year, to extend the application of EEDI to (roll on / roll off (ro-ro)) cargo ships (vehicle carrier), liquid natural gas carriers, cruise passenger ships having non-conventional propulsion, ro-ro cargo ships and ro-ro passenger ships; and to exempt ships not propelled by mechanical means, and platforms including FPSOs and FSUs and drilling rigs, regardless of their propulsion; as well as cargo ships having ice-breaking capability.

Regulation of extreme ice loads acting on hulls of azimuth propulsion systems for ice ships

Vessels with an azimuth propulsion system (APS), including double-acting tankers (DATs) designed for autonomous ice navigation in astern-running mode, which makes it possible to improve their icebreaking capability and operation performance in open water by means of bow shape optimisation, are considered to be promising ship types for hydrocarbon and ore material transportation along Arctic Passage routes. This paper covers the regulation issues of the extreme ice loads on the APS pods of conventional ships and DATs. It was traditional for Russian practice to use a hydrodynamic model (HDM) of solid body/ice impact; however the latest full-scale and laboratory experiments carried out in Russia, as well as abroad, show a higher degree of ice load localisation (or peaks) as compared with HDM predictions. For the regulation of the ice loads on the DAT azimuth propulsion system, a modified hydrodynamic model (MHDM) is used, which provides both satisfactory agreement with the experimental data and a good succession of the HDM's approaches and empiric coefficients. This paper suggests an approximate formula for the ice force determination, and this formula is based on MHDM approaches. The paper covers the methods of regulating the calculated parameters for the APS ice impact under ahead-running, astern-running and in circulation mode. It also considers the possibility for creating an efficient APS protection from ice impact under astern-running, and takes into account the double-acting tanker APS specifics. The paper suggests an engineering calculation model to determine the load on DAT APS when the vessel goes through an ice ridge under astern-running mode. It examines the case of the ridge keel interaction not only with the blades of the pulling propeller, but with the APS pod as well. The paper also considers the circumstance that the areas of the ridge keel adjacent to the zone destroyed in the course of interaction with the propeller blades are rather hollow.

Scientific promotion of 60 MW general-purpose nuclear icebreaker designing

The nuclear icebreaking fleet is the basis of the Russian Federation's national safety in the Arctic, and it plays the governing role in provision of shipping along the Northern Sea Route. Nuclear icebreakers are federal owned and their development is financed by the state budget. The government is actively pursuing development of nuclear icebreakers of the new generation with icebreaking capability of up to 3 m. The icebreaker is presently under detailed design conducted by the leading Russian companies (experienced in the design of the nuclear icebreakers of the previous generation) headed by JSC ‘Iceberg’. The Krylov Shipbuilding Research Institute participates in the detailed design of a new universal nuclear icebreaker, finding solutions for essential issues. First of all, it relates to the development of an optimised shape for the hull in order to ensure unique icebreaking capabilities never achieved before by any other icebreaker in the world. The Krylov Shipbuilding Research Institute investigates the other important issues.

An Icy Partnership

Knowledge of the world9s polar regions--Antarctica and the Arctic--is of international interest for economic, environmental, territorial, and security reasons. Studying these environments has been a cooperative activity among countries for half a century. Icebreaker ships have played a critical role. Unfortunately, the U.S. icebreaking capability has deteriorated substantially. Of the world9s roughly 50 high-capability icebreakers (at least 10,000 horsepower and capable of steaming steadily through ice 4 to 8 feet thick), Russia possesses 15. Canada operates six. The U.S. government owns three, two of which are at the end of their 35-year service lives. This not only threatens U.S. access to these regions but also jeopardizes the ability of the U.S. research community to conduct solo and international research missions. A long-lived successful partnership between the polar research community and the U.S. Coast Guard (USCG), which operates the government icebreakers, has been built over decades. That partnership is unhealthy now and should be revitalized.