Scaled outdoor experimental analysis of ventilation and interunit dispersion with wind and buoyancy effects in street canyons

•Scaled outdoor experiments were conducted in street canyons in two weather periods.•Tracer gas method using CO2 was adopted to simulate interunit transmission routes.•Ar was induced to examine the interactions between buoyancy force and wind force.•Ventilation and interunit dispersion under the rea...

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Bibliographic Details
Published in:Energy and buildings 2022-01, Vol.255, p.111688, Article 111688
Main Authors: Dai, Yuwei, Mak, Cheuk Ming, Hang, Jian, Zhang, Fuyao, Ling, Hong
Format: Article
Language:English
Subjects:
Air flow
Buoyancy
Buoyancy effect
Dispersion
Interunit dispersion
Pollutants
Pollution dispersion
Scaled street canyon
Street canyons
Tracer gas
Trends
Urban environment
Urban environments
Ventilation
Wind
Wind effects
Wind forces
Wind speed
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Summary:•Scaled outdoor experiments were conducted in street canyons in two weather periods.•Tracer gas method using CO2 was adopted to simulate interunit transmission routes.•Ar was induced to examine the interactions between buoyancy force and wind force.•Ventilation and interunit dispersion under the real urban environment were studied. Driven by wind and buoyancy effects in the urban environment, ventilation performance and pollutant transmission are highly related to human health. In order to investigate characteristics of the single-sided natural ventilation and interunit dispersion problem, this study conducted scaled outdoor experiments in summer and winter periods in two-dimensional street canyons. Tracer gas method was adopted to predict the ventilation rate and simulate the pollutant dispersion. It was found the ventilation performance of windward and leeward rooms showed different trends with wind velocities. Archimedes number Ar was used to examine the interactions of the buoyancy and the wind forces. It revealed that the non-dimensional ventilation rates of all rooms were generally smaller than the results of buoyancy effect only. It indicates that interactions between the buoyancy and wind effects were destructive, which reduced the ventilation rates. The interunit dispersion characteristics with the wind effect were highly dependent on source locations. The results of the tracer gas concentrations of the reentered rooms were not showing simple increasing or decreasing trends. This study provides authentic and instant airflow and pollutant dispersion information in an urban environment. The dataset of this experiment can offer validations for further numerical simulations.
ISSN:0378-7788
1872-6178
DOI:10.1016/j.enbuild.2021.111688