Development of vertical wind and turbulence profiles of wind tunnel boundary layers

Ventilation is considered one of the most important factors for livestock and plant environmental control. However because of the difficulties of conducting field experiments, aerodynamic studies of ventilation and HVAC of agricultural buildings are difficult and expensive to conduct effectively in full-scale buildings. A wind tunnel can be the most powerful technology for studying aerodynamics because it works with real airflow and the boundary conditions can be easily changed. A large, multi-purpose wind tunnel was built at the National Institute of Agricultural Engineering (NIAE) in Korea in 2002. In this research, the formation of boundary layers, such as vertical wind and turbulence profiles, in the test section of the wind tunnel was studied to determine ventilation efficiency and internal airflow characteristics of naturally ventilated buildings. Compared to measured data, it was found that the optimum wind and turbulence profiles of a 20 in boundary layer could not be achieved using the theory and experimental procedures of civil and architectural engineering because that would require several hundred meters of boundary layer thickness. Moreover, it was impossible to achieve 30% turbulence intensity just above the floor. Finally, it was found that lattice and blocks could be effectively used to design an optimum boundary layer for aerodynamic study of agricultural buildings. When using lattice and blocks, the wind and turbulence profiles were seriously affected by the distance between the lattice and the measurement location, by the distance between adjacent bars of lattice, and by the width of the bars.