Sea Spray Icing of Drilling and Production Platforms
ENGINEER RESEARCH AND DEVELOPMENT CENTER HANOVER NH COLD REGIONS RESEARCH AND ENGINEERING LAB
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Because of the observed decrease in the ice cover in the Beaufort and Chukchi Seas, it is possible that spray icing of rigs used for oil exploration and drilling may be more frequent and possibly more severe in the coming years than it has been in the past. In this report we describe a model for sea spray icing on fixed offshore structures. The accretion of small sea spray droplets onto two-dimensional structural sections and components depends on the liquid water content of the spray cloud, as well as wind speed, droplet diameter, and the diameter of the object. The spray clouds liquid water content is obtained from the flux of film, jet, and spume droplets from the ocean surface and the vertical velocity of the droplets. The spray droplet flux increases dramatically with increasing wind speed, as whitecaps cover more of the ocean surface and the wind shears droplets off the wave crests. The more massive larger droplets tend to fall out of the spray cloud as a result, the liquid water content decreases with height. We present modeled icing rates for the semi-submersible drilling rigs Ocean Bounty in the winter of 1979-1980 and the Sedco 708 in January 1983. These results are compared to available information on the icing rate or the ice accumulation.
- Mining Engineering
- Snow, Ice and Permafrost
- Marine Engineering