Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Building Services Engineering | en_US |
| dc.creator | Chan, Siu-keung | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/6402 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | - |
| dc.rights | All rights reserved | en_US |
| dc.title | Lightning-caused surface charge/current density on metallic roof of structure | en_US |
| dcterms.abstract | In previous lightning research, there are few discussions on the prediction of lightning and the effects of downward leader on building structures before lightning strike. These are the main motivation to implement the current research project. The research purpose is to establish a lightning model with numerical and graphical simulations and evaluate the existing standard of lightning protection methods in International Electrotechnical Commission Standard (IEC) 62305. In this study, lightning phenomenon factors from lightning models by previous researchers has been compared and summarized. Fundamental electrostatic theories including Poisson's equation and Coulomb's Law are employed to develop a lightning model with reasonable lightning factors such as 10 kV/m, ambient electric field and 10m diameter of downward leader. COMSOL Multiphysics software by using Finite Element Method (FEM) is also applied to simulate a series of 3D lightning models on the computation of the strength of electric field and the surface charge density on the metallic roof under thundercloud conditions with and without downward leader. The results of the investigations have demonstrated (i) the strength of electric field and surface charge level, (ii) the intensification factors of electric field and surface charge density intensified by varied structure height and the shielding effect of adjacent structures and (iii) the evaluation of the collection area applied on lightning protection system in IEC 62305. By the numerical analysis in this research, the current induced on the metallic roof by time-varying change of induced charges under different velocity of downward leader is achieved and thus a possible prediction method such as current sensing equipment could be developed to give an approaching lightning warning for "Active" lightning protection. | en_US |
| dcterms.extent | x, 70, [13] leaves : ill. (chiefly col.) ; 30 cm. | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2012 | en_US |
| dcterms.educationalLevel | All Master | en_US |
| dcterms.educationalLevel | M.Eng. | en_US |
| dcterms.LCSH | Lightning protection. | en_US |
| dcterms.LCSH | Metal roofing. | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.accessRights | restricted access | en_US |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b24497885.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 3.93 MB | Adobe PDF | View/Open |
Copyright Undertaking
As a bona fide Library user, I declare that:
- I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
- I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
- I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.
Please use this identifier to cite or link to this item:
https://theses.lib.polyu.edu.hk/handle/200/6402