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"Icebreakers (Ships)"
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Icebreakers
Traveling by boat in cold climates would be extremely difficult without icebreakers. These special boats help create paths in ice that allow other vessels to travel frigid, ice-filled waters to deliver people and supplies to places often inaccessible without their hard work. Readers will dive in to explore how icebreakers work and what special tools they have to keep other boats safe in the water. Full-color photographs show icebreakers leading ships to Antarctica and other ice breaking projects while exploring the other places these boats work around the world. Detailed Table of Contents, Full-Color Photographs, Further Information Section, Glossary, Graphic Organizers, Index, Sidebars, Websites.
Book
Numerical Study of the Cavitation Performance of an Ice-Blocked Propeller Considering the Free Surface Effect
Propeller cavitation performance can be predicted based on model tests or simulations. However, the cavitation performance of an ice-blocked propeller near the free surface differs from that of a propeller in the cavitation tunnel. Therefore, research on the cavitation performance simulation of propellers near the free surface holds crucial scientific significance. In this study, a coupled model was established using Computational Fluid Dynamics (CFD) and the Volume of Fluid (VOF) coupling method. The CFD-VOF model weighted the overlapping grids and simulated the cavitation performance of an ice-blocked propeller using various immersion depths, cavitation numbers, and advance coefficients. The propeller inflow ahead of the propeller and the wake field behind it were controlled to accurately obtain the propeller cavitation performance. Moreover, a comparison was conducted between the cavitation tunnel test results and the numerical simulation results at various immersion depths. When the immersion depth was at a distance of 1D, the effect of the free surface on the propeller cavitation performance became significant. When the immersion depth was at a distance of 9D, the average errors between the numerical simulation and the model test data were within 10%. This study analyzed the cavitation performance of ice-blocked propellers near the free surface and provided valuable insights for the design of ice-class propellers.
Journal Article
Numerical Simulation of a Polar Ship Moving in Level Ice Based on a One-Way Coupling Method
In most previous ice–ship interaction studies involving fluid effects, ice was taken as unbreakable. Building breakable level ice on water domain is still a big challenge in numerical simulation. This paper overcomes this difficulty and presents a numerical modeling of a ship moving in level ice on the water by using a one-way CFD-DEM (computational fluid dynamics-discrete element method) coupling method. The detailed numerical processes and techniques are introduced. The ice crack propagation process including radial and circular cracks have been observed. Numerical results are compared with previous experimental data and good agreement has been achieved. The results show that water resistance is an order of magnitude smaller than ice resistance during the ice-breaking process. Ice resistance shows strong oscillation along with ice failure process, which are affected by ship speed and ice thickness significantly.
Journal Article
Toward the Application of Pulse Width Modulated (PWM) Inverter Drive-Based Electric Propulsion to Ice Capable Ships
The current world geopolitical state has driven significant interest in expanding influence in the polar regions. In order to develop new trade routes and defense of these areas, specialized ice-capable vessels are needed. Traditional propulsion technology utilized for these vessels has featured diesel and turbo electric drives with cycloconverter based technology used for speed regulation. Cycloconverter technology has the major disadvantage of characteristic output voltage waveforms that are very non-sinusoidal which induce harmonic rich currents with their resulting negative effects on total power factor and efficiency. There is also the potential to induce harmonic currents that may increase heat production in power cables, stressing insulation and reducing overall component life. Furthermore, sensitive loads such as control system power supplies may also be affected. The output waveform of a PWM drive has harmonic content that is both less severe, and more easily analyzed with current modeling tools. There are significant technical challenges that need to be assessed when considering PWM drive deployment in ice-capable vessels. This is due to the severe load torques, and torque variation imposed on propeller blades during ice-milling operations. To the authors’ knowledge, an analysis of the behavior of vector-controlled PWM drives to this type of service has not been published in the open literature. This paper presents an initial modeling and simulation study that investigates whether such a PWM drive and associated controller may be effective for ice milling and other operational evolutions for these types of ships.
Journal Article
Healing hearts, stranded ship and disease-fighting mosquitoes
The latest science news, in brief.
The latest science news, in brief.
Journal Article
Polar Icebreakers in a Changing World
The United States has enduring national and strategic interests in the polar regions, including citizens living above the Arctic circle and three year-round scientific stations in the Antarctic.Polar icebreaking ships are needed to access both regions.Over the past several decades, the U.S.
eBook