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

Describes the development of a particle imaging velocimetry (PIV) measurement system for use with full-scale room airflows. Two-dimensional airflows were measured in a full-scale room in order to validate the PIV system, using two typical ventilation schemes: cross-flow ventilation and return flow ventilation. In the former, a slot air inlet and a slot air outlet were positioned on opposite walls so the ventilation air moved across the room air space. In the latter, the air inlet and the outlet were positioned at the top and bottom of the same wall so that the ventilation air formed a return airflow pattern. Air flow patterns and air velocity vector maps for the entire room cross section are included in the measurements. The paper presents the system configuration, instrumentation, and equipment development, measurement capability and results. For regions with very low velocity especially, the results show that the PIV technique can be an effective method to quantitatively measure the room air velocity. Air velocity distribution measured in this way can be used to analyse ventilation system performance and strategies. The third-dimensional velocity component becomes substantial as the ventilation rate increases even with slot inlet and ventilation rate increases. This indicates that three-dimensional velocity profiles are needed for development of CFD models.