engleski

Effects of wind characteristics on natural ventilation of buildings

Natural ventilation is a process of supplying the fresh air in the indoor space and removing the saturated air from the indoor space without using a mechanical device. The driving forces for this air exchange are the buoyancy and the flow momentum. At a time of increasing electrical consumption and environmental pollution, it is important to promote this environmentally friendly technology. To exploit its full potential, it is necessary to properly understand the relationship between parameters that affect its effi ciency. Therefore, small-scale model experiments were carried out in a boundary layer wind tunnel at the Institute of Fluid Mechanics and Heat Transfer at the Graz University of Technology, Austria. It was attempted to determine the influence of inflow characteristics on the characteristics of a natural ventilation of a stand-alone cubic building as well as of a building situated in an urban environment. The atmospheric boundary layer was successfully modeled to simulate flow over rural and suburban terrain types. A hot-wire anemometry system was used to measure turbulent flow characteristics, while tracer gas system was employed to determine air exchange rates. Experiments were conducted for single-side and cross-ventilation arrangements of the studied building model. The analyzed parameters include the flow velocity and its incidence angle as well as a distance between the buildings. The experimental results indicate that the natural ventilation has similar patterns for both studied atmospheric boundary layer models, whereas the rural-type atmospheric boundary layer model is more sensitive to the changes of input parameters. Air change rate is larger for larger wind velocities, as well as for cross-ventilated buildings compared to the single-side ventilation arrangement.

Atmospheric boundary layer ; natural ventilation ; turbulence ; rural terrain ; suburban terrain ; wind tunnel experiment

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