Thermal Behavior and Growth of Submerged Ice Blocks: Experimental and Numerical Results

摘要

Ice rubble forms when flexural, shear or compressive forces cause broken ice to pile up at the interface between ice floes or during contact with a structure. The accumulation of rubble into linear features results in the formation of ridges, which are comprised of many individual blocks that are bonded with varying degrees of strength. Essential to the overall consolidation of a ridge is the bonding process that takes place at the interface between individual blocks. In this paper initial experimental and numerical simulations are presented that show the amount of new ice that will grow when an initially cold piece of freshwater ice is submerged in freshwater at 0℃. Understanding the thermal behavior of an ice block is important as the results can be used to understand the freeze-bonding processes that occur between two ice blocks, and further extended to understand the processes that occur between multiple ice blocks (i.e., pressure ridges and ice rubble). In the experiments presented herein, a cylindrical ice sample with an initial temperature of -20℃ was submerged in a tank of water at 0℃. As the ice cylinder is initially colder than the surrounding water, heat is diffused from the water into the ice cylinder causing a new layer of ice to form around the samples. Wireless temperature sensors with onboard data loggers were placed inside the ice cylinder to measure temperature. The radius, length and weight of the sample were measured before and after the submersion to calculate the thickness of the new ice layer. COMSOL Multiphysics was employed to analyze the freezing rate and the radial temperature profile of the sample. An analytical method is also used to calculate the maximum thickness of the new ice layer formed around the sample once the temperature has equilibrated to the surrounding water temperature. Results obtained using the analytical method are then compared with experimental results. Temperature profile data collected at specified locations within the ice have also been compared with the numerical simulations. Good agreement between measured and simulated results was observed.