Sökning: "lightning attachment"

Hittade 5 avhandlingar innehållade orden lightning attachment.

1. 1. On the Attachment of Lightning Flashes to Grounded Structures

   Författare :Marley Becerra; Vernon Cooray; Rajeev Thottappillil; Mats Boman; Ivo Gallimberti; Uppsala universitet; []
   Nyckelord :Engineering physics; Lightning; Lightning attachment; Positive leader discharges; Lightning protection; Thunderstorms; Numerical modeling; Teknisk fysik;

   Sammanfattning : This thesis deals with the physical modeling of the initiation and propagation of upward positive leader discharges from grounded structures during lightning strikes. It includes the analysis of upward leaders initiated under the influence of the electric field produced by a dominant negative cloud charge and due to the combined action of a negative thundercloud and a descending downward stepped negative leader. LÄS MER

3. 2. Numerical Simulations of Long Spark and Lightning Attachment

   Författare :Liliana Arevalo; Vernon Cooray; Dan Windmar; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; breakdown; discharge; leader channel; lightning attachment; negative discharge; positive discharge; streamer; Electrical engineering; Elektroteknik; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

   Sammanfattning : The research work presented here is concerned with numerical simulations of two different electrical phenomena: Long gap electrical discharges under switching impulses and the lightning attachment process associated with positive upward leaders. The development of positive upward leaders and the progression of discharges in long gaps are attributable to two intertwined physical phenomena, namely, the leader channel and the streamer zone. LÄS MER

4. 3. On the Attachment of Lightning Flashes to Wind Turbines

   Författare :Mengni Long; Marley Becerra; Rajeev Thottappillil; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wind turbines; upward lightning; lightning attachment of dart and dart-stepped leaders;

   Sammanfattning : The work presented in this thesis aims at investigating the attachment of lightning flashes to wind turbines. Modern wind turbines are highly exposed to lightning strikes, due to the increase of their height and the rotation of the blades. Upward lightning is the dominant mechanism of lightning strikes to them. LÄS MER

5. 4. Numerical simulations of long spark gaps – lightning attachment and its application

   Författare :Liliana Arévalo Gonzalez; Uppsala universitet; []
   Nyckelord :TECHNOLOGY; TEKNIKVETENSKAP;

   Sammanfattning : The Licenciate Thesis presented here is a research work on numerical simulations of two different electrical phenomena: Long gap discharges under switching impulses and the lightning attachment process of positive upward leaders. The development of a positive upward leader and the process of progress of a discharge in long gaps are composed of two intertwined physical phenomena, namely the leader channel and the corona zone. LÄS MER

7. 5. Positive streamer discharges in air and along insulating surfaces: experiment and simulation

   Författare :Mose Akyuz; Fridolin Heidler; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering physics; Teknisk fysik; Engineering physics; Teknisk fysik; teknisk fysik med inriktning mot atmosfäriska urladdningar; Engineering Physics; with a direction to Atmospheric Discharges;

   Sammanfattning : The power quality of modern society relies on the electrical properties of the dielectric insulators used in the power industry. Much research work has been conducted with an aim to understand and predict the insulating behaviour of such materials under different kinds of atmospheric conditions, but still there are many unsolved problems. LÄS MER