Ship Superstructure Icing: Crystalline and Physical Properties
Abstract
In February and March 1990, measurements were made of superstructure ice on a United States Coast Guard cutter in the Bering Sea. Ice samples were removed from bulkheads, decks, and icicles during two icing events. Ice crystal measurements included crystal size, shape, orientation, brine pocket location, size and shape, internal layering, and air bubble sizes. Ice property measurements included salinity density, and temperature, with computed estimates of air and brine volume. Texturally, accreted ice resembled frazil ice that forms from consolidation of freely nucleated ice crystals in sea water. This resemblance is also reflected in bulk, ranging from 7 to 24%o. The crystalline structure of accreted ice ranged from rounded to polygonal. Generally, rounded crystals would be expected for ice formed from sea spray droplets. The occurrence of polygonal crystals is attributed to thermally driven modification after deposition. No trend towards reorientation of crystallographic c-axes in either freshly accreted or thermally modified ice was observed. Mean crystal sizes ranged from 0.56 to 1.15 mm, with even larger crystals in icicles. Ice salinity averaged about 12%o on bulkheads and about 21%o on decks. Ice densities ranged from 0.69 to 0.92 Mg m-3 and were generally higher on decks. Bulkhead ice had larger computed total porosity and air volume, a d lower brine volume than deck ice. Samples taken from decks and bulkheads generally compared well with Russian and Japanese measurements.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2000
- Accession Number
- ADA381910
Entities
People
- Anthony J. Gow
- Charles C. Ryerson
Organizations
- Engineer Research and Development Center