UID:
kobvindex_GFZ20190425145959
Format:
vi, 50 Seiten
,
Illustrationen
Series Statement:
CRREL Report 84-18
Content:
This report investigates the influences of turbulence and water temperature on frazil ice formation. The rate and thequantity of frazil ice formed in a specified volume of supercooled water increase with both increasing turbulence inten-sitv and decreasing water temperature. The influence of turbulence intensity on the rate of frazil ice formation, how-ever. is more pronounced for larger initial supercooling. The turbulence characteristics of a flow affect the rate offrazil ice formation by governing the temperature to which the flow can be supercooled, by influencing heat transferfrom the frazil ice to surrounding water, and by promoting collision nucleation, particle and floc rupture and increasingthe number of nucleation sites. larger frazil ice particles formed in water supercooled to lower temperatures. The par-ticles usually were disks, with diameters several orders greater than their thickness. Particle size generally decreased with increasing turbulence intensity. This report develops an analytical model, in which the rate of frazil ice formation isrelated to temperature rise of a turbulent volume of water from the release of latent heat of fusion of liquid water toice. Experiments conducted in a turbulence jar with a heated, vertically oscillating grid served both to guide and tocalibrate thanalytical'model as well as to afford insights into frazil ice formation. The formation of frazil ice wasstudied for Vemperatures of supercooled water ranging from -0.9° to -0.050°C.
Note:
CONTENTS
Abstract
Preface
Nomenclature
Introduction
Background
Scope of study
Literature review
Introduction
Incipient formation of frazil ice
Particle size and evolution of frazil ice
Influences of turbulence and water temperature on the rate of frazil ice formation
Conclusions
Analytical model
Introduction
Elements of heat transfer
Elements of turbulence
Experimentation
Experimental apparatus
Experimental procedure
Results
Introduction
Nucleation of frazil ice
Influences of turbulence on frazil ice formation
Water temperature
Influences of water temperature and turbulence on the concentration of frazil ice
Frazil ice particle shape and size
Conclusions
Literature cited
Appendix A: Preliminary frazil ice experiments
Flume experiments
Couette-flow
Appendix B: Listing of computer program for calculation of frazil ice formation
Appendix C: Water temperature rise attributable to frazil ice formation as computed usingthe analytical model .
In:
CRREL Report, 84-18
Language:
English
Keywords:
Forschungsbericht
URL:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a147425.pdf
URL:
https://hdl.handle.net/11681/9547
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