ASHRAE LO-09-084

Abstract

<strong>ABSTRACT</strong> <br><em>This paper describes the experimental and numerical investigation of airflows in a full-scale ventilated room. The Volumetric Particle Streak-Tracking Velocimetry (VPSTV) was used to measure the three spatial components of air velocities at three ventilation rates: 3 ach, 8.6 ach, and 19.5 ach (Air Change per Hour). Reattachment length and jet penetration length measured at seven different ventilation rates ranging from 3 ach to 100 ach were also reported. The data obtained from the experiments were used to validate different numerical models, including turbulence models based on the Reynolds- Averaged Navier-Stokes (RANS) method and the Large Eddy Simulation (LES) with dynamical subgrid model. It was observed that one primary central recirculation vortex was formed in the middle of the room and one secondary small vortex existed near the left bottom corner. The sizes and positions of the two vortices varied with the ventilation rates: the central vortex became fuller and moved towards the center of the room with increasing ventilation rates; on the other hand, the secondary vortex became smaller and moved toward the left bottom corner. The reattachment length and jet penetration length showed a strong dependence on the ventilation rates and became relatively constant once the ventilation rate reached a threshold value of 19.5 ach. The LES generated the best predictions for the three ventilation rates while Reynolds Stress Model (RSM) predictions were closest to measurements among the RANS models. The outcome of the study will allow scientists to gain a better understanding of airflows and be useful in designing better ventilation systems that will improve the air quality and human health in indoor environments, such as offices, aircraft cabins, and other working environments.</em>