Experimental Investigation of the Resistance Performance and Heave and Pitch Motions of Ice-Going Container Ship Under Pack Ice Conditions

In order to analyze the ice-going ship’s performance under the pack ice conditions, synthetic ice was introduced into a towing tank. A barrier using floating cylinder in the towing tank was designed to carry out the resistance experiment. The test results indicated that the encountering frequency between the ship model and the pack ice shifts towards a high-velocity point as the concentration of the pack ice increases, and this encountering frequency creates an unstable region of the resistance, and the unstable region shifts to the higher speed with the increasing concentration. The results also showed that for the same speed points, the ratio of the pack ice resistance to the open water resistance increases with the increasing concentration, and for the same concentrations, this ratio decreases as the speed increases. Motion characteristics showed that the mean value of the heave motion increases as the speed increases, and the pitch motion tends to increase with the increasing speed. In addition, the total resistance of the fullscale was predicted.

Experiments on the Resistance of a Large Transport Vessel Navigating in the Arctic Region in Pack Ice Conditions

In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the Arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail.

Characterization of the summer pack ice biotic community of Canada Basin

Summer pack ice biotic community of the Canada Basin was characterized duringthe Second Chinese National Arctic Research Expedition(CHINARE-2003,20 August—5 September 2003).Bacteria,ice algae(diatoms and autotrophic flagellates)and protozoa(mainly heterotrophicflagellates)were observed throughout the whole ice column.The vertical distribution of biotic taxavaried among sites.The integrated biomass ranged from 48.4 and 58.1 mg/m^(2),with an average of55.2 mg/m^(2).Bacteria were the dominant of the assemblage in pack ice,accounted for 84.1%of theintegrated,and ice algae,which usually dominate the ice biotic community,constituted only 3.5%ofthe total.Considering the quick environmental changes of the Arctic Ocean in recent years,wesuggested that quick melting of pack ice in summer was suggested,which caused such change of packice biotic community.The low salinity throughout the whole ice column and the continuous melting ofthe pack ice cumbered the formation of ice algae bloom in summer,finally resulting in thedominance of microbial food web with bacteria and heterotrophic flagellates as the most obviouscharacteristics.Considering the high ratio of pack ice primary production to the total found inprevious studies,the quick change of pack ice community structure in summer would deeply influencethe marine ecosystem of the high Arctic Ocean.

The progress in the study of Arctic pack ice ecology

The sea ice community plays an important role in the Arctic marine ecosystem. Because of the predicted environmental changes in the Arctic environment and specifically related to sea ice, the Arctic pack ice biota has received more attention in recent years using modern ice-breaking research vessels. Studies show that the Arctic pack ice contains a diverse biota and besides ice algae, the bacterial and protozoan biomasses can be high. Surprisingly high primary production values were observed in the pack ice of the central Arctic Ocean. Occasionally biomass maximum were discovered in the interior of the ice floes, a habitat that had been ignored in most Arctic studies. Many scientific questions, which deserve special attention, remained unsolved due to logistic limitations and the sea ice characteristics. Little is know about the pack ice community in the central Arctic Ocean. Almost no data exists from the pack ice zone for the winter season. Concerning the abundance of bacteria and protozoa, more studies are needed to understand the microbial network within the ice and its role in material and energy flows. The response of the sea ice biota to global change will impact the entire Arctic marine ecosystem and a long-term monitoring program is needed. The techniques, that are applied to study the sea ice biota and the sea ice ecology, should be improved.

Numerical study on critical flow velocity of ice slurry in the pipe of ice source heat pump system

The traditional evaporator of water source heat pump system is easy to freeze when the water source temperature is too low in winter.A novel ice source heat pump system is proposed,which can use low temperature surface water to supply heat to buildings.One of the key problems for safe transportation is velocity range of ice slurry in ice outlet pipeline.In order to study the critical flow velocity of ice slurry in the pipe,an Euler model of horizontal straight pipe and 90°elbow pipe were established by Fluent software.The influence of five factors on the critical flow velocity of two kinds of pipes,including initial ice packing fraction,ice particle size,pipe diameter,length of straight pipe and radius curvature of elbow was studied.It found that the initial ice content should be controlled from 10%to 15%.The inlet flow rate was 20%higher than the critical flow rate under the most unfavorable condition.Ice particle size was less than 0.2 mm.The total length of ice discharge pipeline was less than 50 m.Curvature radius of the bend should be met the minimum requirements of the specification of the pipe used.

Prediction of performance of a non-icebreaking ship in marginal ice zone

The Arctic is rapidly transforming into a navigable ocean because of global warming.The retreat of ice extent and widened marginal ice zone(MIZ)in the Arctic made it possible for non-icebreaking commercial vessels to sail into Arctic waters where ice floes of various concentrations and thicknesses exist.The main objective of this work is to estimate the performance of a non-icebreaking cargo ship that sails in the Arctic marginal ice zone.Different numerical approaches are utilized to calculate ice-induced resistance and compared with those proposed in empirical formulas.The comparison shows that the resistances predicted by the two numerical tools differ obviously and are in general smaller in comparison with the ones calculated from the empirical formulas under lower ice concentrations.The total resistances are further calculated to predict the required propulsion powers for the case study vessel to enable navigation under severe ice conditions.This work highlights the significance of developing new and more sophisticated tools for estimation of ship’s ice performance in MIZ,which is the prerequisite to enable non-icebreaking cargo fleet to utilize the Arctic shipping lane.