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Experimental and Theoretical Study of Ventilation and Heat Loss From Isothermally Heated Clothed Vertical Cylinder in Uniform Flow Field

Ghaddar, Nesreen; Ghali, Kamel; Al-Othmani, Mohamad; Holmér, Ingvar LU and Kuklane, Kalev LU (2010) In Journal of Applied Mechanics 77(3).
Abstract
The flow characteristics and heat transfer are studied in a vertical annulus of a heated cylinder surrounded by a permeable cylinder, subject to cross uniform wind with open end to the environment and in the presence of natural convection. The objective here is to develop a computationally efficient model capable of capturing the physics of the flow and heat transport to predict air renewal rates in the vertical annulus. The small quantities of air infiltrating/exfiltrating through the porous cylinder over its upstream/downstream regions do not substantially affect the external flow pattern around the clothed cylinder. The air annulus flow and heat transport model predicted the radial and vertical mass fluxes and the mass flow rate at the... (More)
The flow characteristics and heat transfer are studied in a vertical annulus of a heated cylinder surrounded by a permeable cylinder, subject to cross uniform wind with open end to the environment and in the presence of natural convection. The objective here is to develop a computationally efficient model capable of capturing the physics of the flow and heat transport to predict air renewal rates in the vertical annulus. The small quantities of air infiltrating/exfiltrating through the porous cylinder over its upstream/downstream regions do not substantially affect the external flow pattern around the clothed cylinder. The air annulus flow and heat transport model predicted the radial and vertical mass fluxes and the mass flow rate at the opening as a function of environment conditions, porous cylinder thermal properties, wind speed, and annulus geometry. Experiments were performed in a low speed wind tunnel (0.5-5 m/s), in which an isothermally heated vertical cylinder surrounded by a clothed outer cylinder was placed in uniform cross wind. The tracer gas method is used to predict total ventilation flow rates through the fabric and the opening. Good agreement was found between the model and experimental measurements of air renewal rate and predicted heat loss from the inner cylinder at steady conditions. A parametric study is performed to study the effect of wind speed and temperature difference between the wind and skin temperature on induced ventilation through the clothing and the opening. It is found that natural convection enhances ventilation of the annulus air at wind speed, less than 3 m/s, while at higher speeds, natural convection effect is negligible. As the temperature difference between external wind and inner cylinder surface increases, the vertical air temperature gradient and total upward airflow through the opening increase. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
ventilation, wind, wind tunnels, natural convection, mass transfer, flow through porous media, external flows, clothing, confined flow
in
Journal of Applied Mechanics
volume
77
issue
3
publisher
American Society Of Mechanical Engineers (ASME)
external identifiers
  • wos:000275244500011
  • scopus:77955263397
ISSN
0021-8936
DOI
10.1115/1.4000429
language
English
LU publication?
yes
id
4ab2f342-03e4-44db-b3c5-ae7245de8d00 (old id 1589537)
date added to LUP
2010-04-20 10:23:36
date last changed
2018-05-29 09:32:40
@article{4ab2f342-03e4-44db-b3c5-ae7245de8d00,
  abstract     = {The flow characteristics and heat transfer are studied in a vertical annulus of a heated cylinder surrounded by a permeable cylinder, subject to cross uniform wind with open end to the environment and in the presence of natural convection. The objective here is to develop a computationally efficient model capable of capturing the physics of the flow and heat transport to predict air renewal rates in the vertical annulus. The small quantities of air infiltrating/exfiltrating through the porous cylinder over its upstream/downstream regions do not substantially affect the external flow pattern around the clothed cylinder. The air annulus flow and heat transport model predicted the radial and vertical mass fluxes and the mass flow rate at the opening as a function of environment conditions, porous cylinder thermal properties, wind speed, and annulus geometry. Experiments were performed in a low speed wind tunnel (0.5-5 m/s), in which an isothermally heated vertical cylinder surrounded by a clothed outer cylinder was placed in uniform cross wind. The tracer gas method is used to predict total ventilation flow rates through the fabric and the opening. Good agreement was found between the model and experimental measurements of air renewal rate and predicted heat loss from the inner cylinder at steady conditions. A parametric study is performed to study the effect of wind speed and temperature difference between the wind and skin temperature on induced ventilation through the clothing and the opening. It is found that natural convection enhances ventilation of the annulus air at wind speed, less than 3 m/s, while at higher speeds, natural convection effect is negligible. As the temperature difference between external wind and inner cylinder surface increases, the vertical air temperature gradient and total upward airflow through the opening increase.},
  articleno    = {031011},
  author       = {Ghaddar, Nesreen and Ghali, Kamel and Al-Othmani, Mohamad and Holmér, Ingvar and Kuklane, Kalev},
  issn         = {0021-8936},
  keyword      = {ventilation,wind,wind tunnels,natural convection,mass transfer,flow through porous media,external flows,clothing,confined flow},
  language     = {eng},
  number       = {3},
  publisher    = {American Society Of Mechanical Engineers (ASME)},
  series       = {Journal of Applied Mechanics},
  title        = {Experimental and Theoretical Study of Ventilation and Heat Loss From Isothermally Heated Clothed Vertical Cylinder in Uniform Flow Field},
  url          = {http://dx.doi.org/10.1115/1.4000429},
  volume       = {77},
  year         = {2010},
}