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.",
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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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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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