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  • 1
    Series available for loan
    Series available for loan
    Hanover, NH : U. S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    In: CRREL Report, 93-3
    Description / Table of Contents: Results are presented of a study to determine appropriate methods of flow modification for mitigating ice jam formation in navigable rivers. Based on a review of alternative methods for flow modification, it is concluded that for many rivers, especially large ones, the most appropriate method involves controlled ice-cover formation through the regulation of river flow. Flow discharge and stages would be regulated by controlling the flow releases from reservoirs and flow stages at river dams, such that optimal flow conditions prevail for rapid formation, and subsequent maintenance, of an accumulation ice cover over river reaches in which potentially large amounts of frazil ice may grow. Accumulation covers would be formed of frazil ice pans and floes and, if appropriate, broken ice conveyed from upstream. Existing dams, augmented where needed by navigable ice booms, could serve as retention structures for the development of accumulation covers. A preliminary indication of the feasibility of this method for controlling ice-cover formation on stage-regulated pools of the Ohio River is assessed through the use of a numerical model that simulates ice-cover formation from frazil ice. It is found that this approach holds promise for mitigating jam occurrence, although its implementation necessarily entails management of flow through major portions of the Ohio River. The results of the study are, to a limited extent, generalized to other rivers.
    Type of Medium: Series available for loan
    Pages: v, 58 Seiten , Illustrationen
    Series Statement: CRREL Report 93-3
    Language: English
    Branch Library: AWI Library
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  • 2
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-84/18
    In: CRREL Report, 84-18
    Description / Table of Contents: 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.
    Type of Medium: Series available for loan
    Pages: vi, 50 Seiten , Illustrationen
    Series Statement: CRREL Report 84-18
    Language: English
    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 .
    Location: AWI Archive
    Branch Library: AWI Library
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