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Guidelines for Meteorological Icing Models, Statistical Methods and Topographical Effects

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Guidelines for Meteorological Icing Models, Statistical Methods and Topographical Effects 291 GUIDELINES FOR METEOROLOGICAL ICING MODELS, STATISTICAL METHODS AND TOPOGRAPHICAL EFFECTS Working Group B2.16 Task Force 03 April 2006 GUIDELINES FOR METEOROLOGICAL ICING MODELS, STATISTICAL METHODS AND TOPOGRAPHICAL EFFECTS Task Force B2.16.03 Task Force Members: André Leblond – Canada (TF Leader) Svein M. Fikke – Norway (WG Convenor) Brian Wareing – United Kingdom (WG Secretary) Sergey Chereshnyuk – Russia Árni Jón Elíasson – Iceland Masoud Farzaneh – Canada Angel Gallego – Spain Asim Haldar – Canada Claude Hardy – Canada Henry Hawes – Australia Magdi Ishac – Canada Samy Krishnasamy – Canada Marc Le-Du – France Yukichi Sakamoto – Japan Konstantin Savadjiev – Canada Vladimir Shkaptsov – Russia Naohiko Sudo – Japan Sergey Turbin – Ukraine Other Working Group Members: Anand P. Goel – Canada Franc Jakl – Slovenia Leon Kempner – Canada Ruy Carlos Ramos de Menezes – Brasil Tihomir Popovic – Serbia Jan Rogier – Belgium Dario Ronzio – Italy Tapani Seppa – USA Noriyoshi Sugawara – Japan Copyright © 2006 “Ownership of a CIGRE publication, whether in paper form or on electronic support only infers right of use for personal purposes. Are prohibited, except if explicitly agreed by CIGRE, total or partial reproduction of the publication for use other than personal and transfer to a third party; hence circulation on any intranet or other company network is forbidden”. Disclaimer notice “CIGRE gives no warranty or assurance about the contents of this publication, nor does it accept any responsibility, as to the accuracy or exhaustiveness of the information. All implied warranties and conditions are excluded to the maximum extent permitted by law”. Final Report of Task Force 3 on “Icing” November 2005 Page 2 of 116 TABLE OF CONTENTS 1. EXECUTIVE SUMMARY................................................................................................................................6 1.1 INTRODUCTION .............................................................................................................................................6 1.2 ICING MODELS..............................................................................................................................................6 1.3 STATISTICAL METHODS ................................................................................................................................7 1.4 TOPOGRAPHICAL EFFECTS ............................................................................................................................7 1.5 APPLICATION OF ATMOSPHERIC BOUNDARY LAYER MODELS......................................................................8 1.6 CONCLUSION ................................................................................................................................................8 2. INTRODUCTION............................................................................................................................................10 3. MODELS FOR ATMOSPHERIC ICING.....................................................................................................11 3.1 ICE ACCRETION PROCESSES........................................................................................................................11 3.1.1 Classification of Icing [5] .................................................................................................................11 3.1.2 Types of Accretion.............................................................................................................................11 3.1.2.1 Glaze Ice ...................................................................................................................................................... 12 3.1.2.2 Rime Ice ....................................................................................................................................................... 12 3.1.2.3 Wet Snow..................................................................................................................................................... 13 3.1.2.4 Dry Snow ..................................................................................................................................................... 14 3.1.2.5 Hoar Frost.................................................................................................................................................... 14 3.1.3 Fundamental Meteorological Parameters Involved in Icing...........................................................16 3.2 ICING MODELS............................................................................................................................................17 3.2.1 Glaze-Icing Models ...........................................................................................................................18 3.2.1.1 Background ................................................................................................................................................ 18 3.2.1.2 Model Review ............................................................................................................................................. 18 3.2.1.2.1 Chaîné and Skeates Model ................................................................................................................ 19 3.2.1.2.2 Makkonen Model [12] .......................................................................................................................... 22 3.2.1.2.3 MRI model [52] ..................................................................................................................................... 25 3.2.1.3 Model Parameters – Input and Output ................................................................................................. 26 3.2.1.4 Model Validation Using Field Data – Freezing Rain.......................................................................... 27 3.2.1.5 Discussion .................................................................................................................................................. 28 3.2.1.6 Effect of Ice Accretion Shape................................................................................................................. 29 3.2.2 Rime-Icing Models............................................................................................................................30 3.2.2.1 Meteorological Parameter Input and Model Output.......................................................................... 30 3.2.2.2 Field Test Validation ................................................................................................................................. 31 3.2.2.3 Fundamentals of Ice Modelling.............................................................................................................. 31 3.2.2.3.1 Rime Ice Accretion Process................................................................................................................ 31 3.2.2.3.2 Icing Rate .............................................................................................................................................. 34 3.2.2.3.3 Stickiness .............................................................................................................................................. 34 3.2.2.3.4 Accretion................................................................................................................................................ 34 3.2.3 Wet-Snow Models..............................................................................................................................35 3.2.3.1 Background for Snow Accretion ........................................................................................................... 35 3.2.3.2 Japanese Cylindrical-Sleeve Model [77].............................................................................................. 36 3.2.3.3 French Cylindrical-Sleeve Model [20, 83, 104, 105, 106].................................................................. 37 3.2.4 Discussion..........................................................................................................................................39 3.3 ICE LOAD ASSESSMENT ON OVERHEAD LINES............................................................................................39 3.3.1 Accretion on Lattice Structures ........................................................................................................40 3.3.1.1 General......................................................................................................................................................... 40 3.3.1.2 Ice Class ...................................................................................................................................................... 40 3.3.1.2.1 Ice Class – Glaze Icing........................................................................................................................ 40 3.3.1.2.2 Ice Class – Rime Icing......................................................................................................................... 40 3.3.2 Ice Accretion Loads on other Structures..........................................................................................43 3.3.3 Ice Loads on Circular Conductors ...................................................................................................44 3.3.3.1 Glaze Icing on Torsionally Stiff Conductors....................................................................................... 44 3.3.3.2
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