Characteristics of openings for wind driven natural ventilation

The project deals with the factors that influence the airflow through purpose provided openings used for wind driven natural ventilation. Factors such as the size and location of the openings, the opening area ratio (Inlet/Outlet), the geometry of the building and the wind direction are included in the investigation. The design procedure of wind driven natural ventilation today is based upon averaged surface pressure coefficients determined from a building without openings and a proportional relation between the airflow rate and the square root of the pressure difference across the opening. The fact that the surface pressure distribution on a building is not uniform and that it may be influenced by the opening itself as well as the mentioned expression does not account for conservation of kinetic energy in the flow are some of the factors that may lead to misleading results. The project contains both a theoretical, experimental as well as numerical (CFD) analysis of the factors that influence the airflow through openings used in wind driven natural ventilation. The experimental part contains a wind tunnel study of the airflow through large openings of various sizes placed in geometrically simple objects as well as the analysis of a scale model building equipped with cross ventilated openings where elements such as the location and size of the openings and the wind direction are analysed. The numerical study contains a comparative analysis to the measurements as well as an extension of these. The numerical analysis should also to some extent lead to the optimisation of CFD as a design tool for natural ventilation. The project is funded through the Hybrid Ventilation Centre Aalborg University and performed in cooperation with KTH, Sweden   Project duration: July 2000 ? July 2003   Persons: Jan Per Jensen True , Per Heiselberg , Peter V. Nielsen , Mats Sandberg