Analysis of Airflow in a Full-Scale Room with Non-Isothermal Jet Ventilation Using PTV Techniques

Draft and non-uniform fresh air distribution are common problems in winter ventilation, especially for large animal buildings. Thermal-based anemometers have difficulties in accurately measuring non-isothermal and low-speed indoor airflow. A new technology, particle tracking velocimetry (PTV), which uses particles and their images to study indoor airflow, can overcome the traditional limitations in indoor airflow measurement. A PTV system was used to characterize indoor airflow in a full-scale ventilated room under nonisothermal ventilation conditions. Non-isothermal mild weather and winter ventilation conditions were simulated to analyze their effects on indoor airflow and air velocities in
animal occupied zones and human breathing zones. It is found that winter ventilation created a totally reversed rotating airflow pattern. Air velocities in the animal occupied zone increased substantially compared with the corresponding isothermal ventilation conditions. Winter ventilation strategies for improvement of airflow distribution were studied: (1) increasing inlet air velocity, (2) increasing inlet air jet momentum by use of air recirculation devices, and (3) decreasing ventilation temperature difference.