Flow around cylindrical towers : the stabalising role of vertical ribs
Date
2006-12
Authors
Alberti, L. I.
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
The aim of this thesis is to study the stabilising effect which vertical ribs may have on a tall
cylindrical structure, with the focus on the proposed Solar Chimney.
The report begins with a brief introduction to the Solar Chimney concept. A study is made of
flow regimes which exist for flow around a circular cylinder and these flow regimes, together
with their characteristics, are described. Various threats to the Solar Chimney are identified
and will be investigated. The natural shape and strength of the Saguaro Cactus leads to the
investigation of vertically ribbed cylinders.
Experimental wind tunnel tests are performed in Tokyo, Japan to obtain external pressure
distributions. A smooth cylindrical model, as well as two different configurations of vertically
ribbed cylinders are tested. These external pressure distributions are numerically integrated in
order to obtain calculated drag coefficient values for the cylinders.
The drag coefficients for a smooth cylinder and cylinders with vertical ribs are obtained
experimentally by means of total drag force measurements. These tests were performed in the
wind tunnel at the University of Stellenbosch. The effect of aspect ratio of a smooth cylinder
is also addressed.
Computational Fluid Dynamics (CFD) analyses are carried out using the CFD software
program, FLUENT. Both the drag coefficient and the external pressure distributions were
investigated in this way. The differences between theoretical conditions and those of real life
conditions of a smooth cylinder are discussed.
The report ends by concluding the stabilising effect of vertical ribs on tall cylindrical
structures and how these ribs may eliminate some of the present threats to the proposed Solar
Chimney.
Description
Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2006.
Keywords
Theses -- Civil engineering, Dissertations -- Civil engineering