Measurement of two-dimensional air velocities in a full-scale room using particle image velocimetry

A particle imaging velocimetry (PIV) measurement system was developed to measure full-scale room airflows. To validate the PIV measurement system, two-dimensional airflows were measured in a full-scale room (5.5 × 3.7 × 2.4 m) under two typical ventilation schemes: cross-flow ventilation and return flow ventilation. In cross-flow ventilation, a slot air inlet and a slot air outlet were placed at opposite walls so that the ventilation air moved across the room air space. In the return airflow ventilation, the air inlet and the outlet were placed at the top and the bottom, respectively, of the same wall so that the ventilation air formed a return airflow pattern. Measurements include airflow patterns and air velocity vector maps for the entire room cross section. The system configuration, instrumentation, and equipment development, measurement capability, and results are presented in this paper. The results show that the PIV technique can be an effective method to quantitatively measure the room air velocity, especially for those regions with very low velocity. The air velocity distribution measured using PIV can be used to analyze ventilation system performance and strategies. Even with slot inlet and slot outlet, the third-dimensional velocity component becomes substantial as the ventilation rate increases. It implies that three-dimensional velocity profiles are needed for development of CFD models.