Modelling the growth of large rime ice accretions

    Research output: Contribution to journalArticleScientificpeer-review

    4 Citations (Scopus)

    Abstract

    The conventional theory of droplet collision with an object can be used only down to a collision efficiency of about 0.1. Therefore, no accurate modelling of in-cloud icing has been possible when droplets are small, wind speed is low, or the object is large. This has also put a limit on the size of an ice accretion on e.g. a power line cable up to which its growth can be simulated. We utilize results of icing wind tunnel experiments and fluid dynamics simulations to explain the differences between the experiments and the theory when the collision efficiency is small. We confirm that the history term in the droplet trajectory equations becomes relevant at small collision efficiencies. Including this term, and applying the integral over the size distribution instead of using themedian volume diameter, shows that accurate modelling of icing at very small collision efficiencies is feasible. This makes it possible to estimate large rime ice loads relevant to structural design.
    Original languageEnglish
    Pages (from-to)133-137
    JournalCold Regions Science and Technology
    Volume151
    DOIs
    Publication statusPublished - Jul 2018
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    rime
    Ice
    collision
    accretion
    ice
    droplet
    modeling
    Fluid dynamics
    power line
    Structural design
    Wind tunnels
    fluid dynamics
    Cables
    wind tunnel
    cable
    Experiments
    Trajectories
    experiment
    wind velocity
    trajectory

    Keywords

    • ice accretion
    • rime ice
    • collision efficiency
    • history term
    • droplet distribution

    Cite this

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    title = "Modelling the growth of large rime ice accretions",
    abstract = "The conventional theory of droplet collision with an object can be used only down to a collision efficiency of about 0.1. Therefore, no accurate modelling of in-cloud icing has been possible when droplets are small, wind speed is low, or the object is large. This has also put a limit on the size of an ice accretion on e.g. a power line cable up to which its growth can be simulated. We utilize results of icing wind tunnel experiments and fluid dynamics simulations to explain the differences between the experiments and the theory when the collision efficiency is small. We confirm that the history term in the droplet trajectory equations becomes relevant at small collision efficiencies. Including this term, and applying the integral over the size distribution instead of using themedian volume diameter, shows that accurate modelling of icing at very small collision efficiencies is feasible. This makes it possible to estimate large rime ice loads relevant to structural design.",
    keywords = "ice accretion, rime ice, collision efficiency, history term, droplet distribution",
    author = "Lasse Makkonen and Zhang Jian and Timo Karlsson and Mikko Tiihonen",
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    Modelling the growth of large rime ice accretions. / Makkonen, Lasse; Jian, Zhang; Karlsson, Timo; Tiihonen, Mikko.

    In: Cold Regions Science and Technology, Vol. 151, 07.2018, p. 133-137.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Modelling the growth of large rime ice accretions

    AU - Makkonen, Lasse

    AU - Jian, Zhang

    AU - Karlsson, Timo

    AU - Tiihonen, Mikko

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    Y1 - 2018/7

    N2 - The conventional theory of droplet collision with an object can be used only down to a collision efficiency of about 0.1. Therefore, no accurate modelling of in-cloud icing has been possible when droplets are small, wind speed is low, or the object is large. This has also put a limit on the size of an ice accretion on e.g. a power line cable up to which its growth can be simulated. We utilize results of icing wind tunnel experiments and fluid dynamics simulations to explain the differences between the experiments and the theory when the collision efficiency is small. We confirm that the history term in the droplet trajectory equations becomes relevant at small collision efficiencies. Including this term, and applying the integral over the size distribution instead of using themedian volume diameter, shows that accurate modelling of icing at very small collision efficiencies is feasible. This makes it possible to estimate large rime ice loads relevant to structural design.

    AB - The conventional theory of droplet collision with an object can be used only down to a collision efficiency of about 0.1. Therefore, no accurate modelling of in-cloud icing has been possible when droplets are small, wind speed is low, or the object is large. This has also put a limit on the size of an ice accretion on e.g. a power line cable up to which its growth can be simulated. We utilize results of icing wind tunnel experiments and fluid dynamics simulations to explain the differences between the experiments and the theory when the collision efficiency is small. We confirm that the history term in the droplet trajectory equations becomes relevant at small collision efficiencies. Including this term, and applying the integral over the size distribution instead of using themedian volume diameter, shows that accurate modelling of icing at very small collision efficiencies is feasible. This makes it possible to estimate large rime ice loads relevant to structural design.

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    KW - rime ice

    KW - collision efficiency

    KW - history term

    KW - droplet distribution

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    U2 - 10.1016/j.coldregions.2018.03.014

    DO - 10.1016/j.coldregions.2018.03.014

    M3 - Article

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    JO - Cold Regions Science and Technology

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