Wind tunnel tests of inter-flat pollutant transmission characteristics in a rectangular multi-storey residential building, part A: Effect of wind direction

Abstract

a b s t r a c tThe inter-flat dispersion of hazardous air pollutants in residential built environment has become a growing concern, especially in crowed urban areas. The purpose of present study is to investigate the wind induced air pollutant transmission and cross contamination routes in typical buildings. In this paper, a series of experiments was carried out in a boundary layer wind tunnel using a 1:30 scaled model that represented the typical configuration of rectangular multi-storey residential buildings in Shanghai. Sulfur hexafluoride (SF 6 ) was employed as tracer gas in the wind tunnel tests. The conditions under two ventilation modes, i.e. single-sided natural ventilation and cross natural ventilation, were compared. The tracer gas concentration distributions under four approaching wind angles were monitored and analyzed. Computational Fluid Dynamics (CFD) method was adopted to assist in analyzing airflow patterns. The experiment results elucidated that in the two ventilation scenarios, both of the vertical and horizontal inter-flat airborne transmission could proceed. The wind direction played a key role on the pollutant concentration distribution. Compared with the single-sided ventilation mode, cross ventilation could weaken the air pollutant dispersion along the vertical direction when the contamination source was on the windward or on the leeward unit. When the wind blowing parallelly to the source unit window, namely the source room was on the sideward, cross ventilation would not suppress the vertical transport on one hand, but reinforce the horizontal transmission on the other hand. The study is helpful for the analysis of infection risk of respiratory diseases in the residential buildings.

Wind tunnel tests of inter-flat pollutant transmission characteristics in a rectangular multi-storey residential building, part B: Effect of source location

“…The experiment methods and instruments used during the measurement process have been mostly described in our previous paper [39]. In this paper, we briefly outlined the experiment arrangement, and gave supplementary introduction on the measurement and analysis of pressure coefficient along the building façade, which was not shown in Ref.…”

“…In this paper, we briefly outlined the experiment arrangement, and gave supplementary introduction on the measurement and analysis of pressure coefficient along the building façade, which was not shown in Ref. [39].…”

“…However, the contaminant from the upstream flat of a building can spread to the downstream units with the airflow, namely disperse from one façade to another [35e38]. Our previous paper [39] qualitatively and quantitatively investigated aforementioned phenomenon and compared the performances of singlesided and cross ventilation under different wind directions with the tracer gas released from a specific unit. The results showed that compared with single-sided ventilation, cross ventilation could weaken the vertical transmission for a specific windward or leeward source and reinforce the horizontal dispersion for a specific sideward source.…”

Airborne spread of expiratory droplet nuclei between the occupants of indoor environments: A review

“…It has become an important research topic within the indoor air sciences . Although airborne transmission has been shown to occur over larger distances, such as between different rooms on a same floor, between different flats in the same building, and even between adjacent buildings, this article focuses only on that within an enclosed indoor space.…”

CFD investigation on the effects of wind and thermal wall-flow on pollutant transmission in a high-rise building

“…Previous onsite tracer gas tests and numerical simulations on buoyancy-forced inter-flat dispersion well explained and quantified the vertically upward transport of gaseous pollutants [24,25]. Subsequently, a series of wind tunnel tests [26][27][28][29][30] and numerical calculations [31][32][33] were carefully carried out to explore the inter-flat transmission dominated by wind force. Mao et al [34] reviewed the mechanisms and evaluation indexes for the airborne transmission and dispersion between flats by single-sided natural ventilation in high-rise residential buildings.…”