scholarly journals Linking ice accretion and crown structure: towards a model of the effect of freezing rain on tree canopies

2016 ◽  
Vol 117 (7) ◽  
pp. 1163-1173 ◽  
Author(s):  
Charles A. Nock ◽  
Bastien Lecigne ◽  
Olivier Taugourdeau ◽  
David F. Greene ◽  
Jean Dauzat ◽  
...  
Keyword(s):  
Ice Accretion ◽  
Freezing Rain ◽  
Crown Structure ◽  
Tree Canopies

A Study of Ice Accretion Shape on Cables Under Freezing Rain Conditions

2002 ◽  
Vol 124 (3) ◽  
pp. 162-168 ◽  
Author(s):  
Krzysztof Szilder ◽  
Edward P. Lozowski ◽  
Gerhard Reuter
Keyword(s):  
Heat Flux ◽  
Transmission Lines ◽  
Center Of Mass ◽  
Flux Ratio ◽  
Horizontal Cylinder ◽  
Ice Accretion ◽  
Atmospheric Conditions ◽  
Freezing Rain ◽  
Ice Load ◽  
Air Temperatures

The influence of atmospheric conditions (specifically precipitation rate and external heat flux) on the freezing rain ice accretion forming on a non-rotating, horizontal cylinder is studied, using an analytical model based on a simple form of the equations for conservation of mass and heat balance. In keeping with the freezing rain application, but in order to simplify this first step, we have assumed vertical incidence of precipitation (no wind) and no dripping from the accretion (hence light to moderate precipitation rates with relatively low air temperatures). The initial ice accretion shape and the location of its center of mass are examined as a function of the ratio of the precipitation mass flux to the total heat flux lost from the ice surface. An increase in the flux ratio leads to a quantifiable downward displacement of the accretion center of mass. We complement this analysis with numerical simulations, using an improved, two-dimensional version of the Szilder-Lozowski morphogenetic model that predicts the evolution of the accretion shape. For the first time, the freezing probability, which is the critical model parameter, is expressed as a function of location and atmospheric conditions for an accretion shape evolving with time. Using the morphogenetic model, we examine the influence of atmospheric conditions on the accretion shape and ice load. In particular, we address the question of what gives rise to extreme ice loads by identifying the range of atmospheric conditions that tends to maximize (or minimize) the ice load for a given amount of precipitation. The results of this research are applicable to predicting ice formation on overhead transmission lines.

Simulation of ice accretion on a cylinder due to freezing rain

1994 ◽  
Vol 40 (136) ◽  
pp. 586-594 ◽  
Author(s):  
Krzysztof Szilder
Keyword(s):  
Random Walk ◽  
Freezing Point ◽  
Water Film ◽  
Model Verification ◽  
Random Walk Model ◽  
Model Parameters ◽  
Ice Accretion ◽  
Atmospheric Conditions ◽  
Freezing Rain ◽  
Modelling Approach

AbstractA hybrid analytical and random-walk model has been developed to predict the shape of ice accreted on a horizontal cylindrical insulator due to freezing rain. The freezing rain occurs with the temperature of the vertically falling raindrops above the freezing point and the air temperature below freezing. The analytical model calculates the angular distribution of the water-film temperature and the location where freezing begins. The random-walk model predicts the accretion shape. The two random-walk model parameters, the freezing probability and the shedding parameter, are expressed as functions of the atmospheric conditions. The model predicts a variety of realistic accretion shapes from cylindrical to icicle-like. Model verification based on comparisons with other models and with experimental results demonstrates quantitatively and qualitatively the credibility of this new modelling approach.

Predicting ice accretion from freezing rain on bridge stay cables

2021 ◽  
pp. 103285
Author(s):  
Krzysztof Szilder ◽  
Annick D'Auteuil ◽  
Sean McTavish
Keyword(s):  
Ice Accretion ◽  
Freezing Rain ◽  
Stay Cables

scholarly journals Simulation of ice accretion on a cylinder due to freezing rain

1994 ◽  
Vol 40 (136) ◽  
pp. 586-594 ◽  
Author(s):  
Krzysztof Szilder
Keyword(s):  
Random Walk ◽  
Freezing Point ◽  
Water Film ◽  
Model Verification ◽  
Random Walk Model ◽  
Model Parameters ◽  
Ice Accretion ◽  
Atmospheric Conditions ◽  
Freezing Rain ◽  
Modelling Approach

AbstractA hybrid analytical and random-walk model has been developed to predict the shape of ice accreted on a horizontal cylindrical insulator due to freezing rain. The freezing rain occurs with the temperature of the vertically falling raindrops above the freezing point and the air temperature below freezing. The analytical model calculates the angular distribution of the water-film temperature and the location where freezing begins. The random-walk model predicts the accretion shape. The two random-walk model parameters, the freezing probability and the shedding parameter, are expressed as functions of the atmospheric conditions. The model predicts a variety of realistic accretion shapes from cylindrical to icicle-like. Model verification based on comparisons with other models and with experimental results demonstrates quantitatively and qualitatively the credibility of this new modelling approach.

scholarly journals Forecasting severe ice storms using numerical weather prediction: the March 2010 Newfoundland event

2011 ◽  
Vol 11 (2) ◽  
pp. 587-595 ◽  
Author(s):  
J. Hosek ◽  
P. Musilek ◽  
E. Lozowski ◽  
P. Pytlak
Keyword(s):  
Numerical Weather Prediction ◽  
Weather Prediction ◽  
Storm Event ◽  
Rain Event ◽  
Ice Accretion ◽  
Ice Storm ◽  
Forecast Horizon ◽  
Freezing Rain ◽  
Numerical Weather ◽  
Ice Storms

Abstract. The northeast coast of North America is frequently hit by severe ice storms. These freezing rain events can produce large ice accretions that damage structures, frequently power transmission and distribution infrastructure. For this reason, it is highly desirable to model and forecast such icing events, so that the consequent damages can be prevented or mitigated. The case study presented in this paper focuses on the March 2010 ice storm event that took place in eastern Newfoundland. We apply a combination of a numerical weather prediction model and an ice accretion algorithm to simulate a forecast of this event. The main goals of this study are to compare the simulated meteorological variables to observations, and to assess the ability of the model to accurately predict the ice accretion load for different forecast horizons. The duration and timing of the freezing rain event that occurred between the night of 4 March and the morning of 6 March was simulated well in all model runs. The total precipitation amounts in the model, however, differed by up to a factor of two from the observations. The accuracy of the model air temperature strongly depended on the forecast horizon, but it was acceptable for all simulation runs. The simulated accretion loads were also compared to the design values for power delivery structures in the region. The results indicated that the simulated values exceeded design criteria in the areas of reported damage and power outages.

PREDICTING AND REDUCING GLAZE ICE ACCRETION ON ELECTRIC POWER LINES WITH JOULE HEATING: THEORY AND EXPERIMENTS

1999 ◽  
Vol 23 (1A) ◽  
pp. 51-70 ◽  
Author(s):  
G.F. Naterer ◽  
H. Deng ◽  
N. Popplewell
Keyword(s):  
Electric Power ◽  
Joule Heating ◽  
Power Transmission ◽  
Power Lines ◽  
Ice Accretion ◽  
Freezing Rain ◽  
Ambient Temperatures ◽  
Ice Accumulation ◽  
Air Interface ◽  
Theoretical Predictions

An analytical model is developed for the prediction of glaze ice accretion with runback water for electric power lines including the Joule heating effect. In this model, the external air flow is coupled with the liquid film flow by slip (non-zero velocity) boundary conditions a the liquid-air interface. In this way, corrections to previous rime ice models are given in order to account for runback water and its effect on wet ice growth in freezing rain conditions with ambient temperatures slightly below 0[°C]. Also, the process of Joule heating in icing conditions is examined from a thermodynamic optimization viewpoint in a manner which permits efficient power transmission while dissipating heat in order to reduce ice accumulation. Good agreement is achieved between theoretical predictions of the glaze ice accretion and experimental results from the freezing rain simulator at the University of Manitoba.

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