Research On The Laws Of Pollutants Spread Around The Window Opening Construction

The air quality of indoor and outdoor environment is closely related to people’shealth, but in the past, when researched on the law of diffusion of pollutants aroundbuilding community, the buildings were usually simplified into a closed regulargeometric shapes (eg, cuboid), this was inconsistent with the actual situation. Actually,people will open the window to improve the indoor air quality based on differentseasons, especially in spring and autumn. When windows open, vents in the buildingfacades are formed, therefore the flow field and pressure field will be affected,furthermore the diffusion of pollutants spread around the construction with windowwill be affected. In addition, building facades form certain heat flux density because ofsolar radiation in different seasons will change the flow field distribution in street area,thereby the pollutant dispersion will be affected. Therefore, the study of the diffusiontransport of pollutant consider different factors around the window openingconstruction has important significance.In this paper, put the fine particles released from automobile exhaust pollutants asthe research object, considered the case of window opening degree in different season,the flow field, pressure field and particle concentration distribution were researched byusing the numerical methods. In addition, for the leeward wall heat flux densityconditions, the flow field and particle concentration distribution around windowopening construction in different wind speed and direction were also simulated andcalculated.The results of this study showed that: when the wind vertical blow to the building,flow field in building facades vents interaction with the street area can enhance verticalairflow, and conducive to high-altitude particle diffusion with the flow. With thewindow opening degree (window opening ratio) increases, strengthening the role ofvertical airflow in street area enhanced, meanwhile, to windward building ventilationrooms of airflow has a role in promoting, and effects on the leeward buildingventilation rooms is not obvious. Static pressure value of each point was less affectedby the window opening degree on the windward side of the building windward andleeward side of the leeward building along the height direction, however, the staticpressure points on both sides of the building blocks were more affected by the windowopening degree, that could not be ignored. With higher window opening degree, theparticulate pollutants in street area easily discharged to the outside with the wind, butventilation households in central and lateral of building with higher window openingdegree will earlier contaminated than the case of lower window opening degree andwithout window.To the window opening construction with heat flux density in leeward, particulatepollutants easily transport to the street outside in the case of yaw wind. When thecertain speed wind vertical blow to building, airflow whirlpool in street will closer to the leeward construction because of wind speed increases, and particles transported byair movement will arrive leeward construction early so that pollute its airy rooms.However, for its spread relatively fast, pollutants in lateral sides of the building will betransported away from the building in the direction easily. When the wind speedincreases to a certain extent, the particles in central would spread out hardly. As awhole, there is a certain critical value to promote particles dilution, when the particlesexceed the threshold it will hinder the spread of the particles. Thermal effects ofleeward, which affect the flow field and particle concentration, is different dependingon the wind velocity. For smaller wind speed, particulate pollutants is spread primarilydriven by thermophoretic force, while larger wind speed, wind field are starting aleading role.