Research on airflow movement characteristics of a nuclear facility plant based on PIV tests

To study the characteristics of indoor airflow movement in a nuclear facility plant with strong heat sources, an actual full-scale equipment room test environmental chamber is established, and the airflow movement of the natural convection and mechanical ventilation conditions in the evaporator area of the chamber is accurately measured based on the particle image velocimetry (PIV) technology, and the velocity measurement of the open area under the maintenance condition of the equipment room is carried out. The results show that under natural convection conditions, the hot wall of the evaporator will cause a specific flow field to be generated around it, forming an upwelling with gradually increasing temperature and velocity, and a rising hot plume will be formed at the top of the evaporator. Under the condition of mechanical ventilation, the thickness of the boundary layer on the surface of the evaporator is reduced, and the hot plume at the top of the evaporator is disturbed and dispersed by the ventilation airflow, which reduces the accumulation of the rising hot plume and makes it more evenly distributed on the top of the equipment room. Under the maintenance conditions, the outdoor airflow enters the environmental chamber through the maintenance opening under differential pressures. When the opening flow velocity is 1 m/s, the inlet velocity curve is parabolic. When the flow velocity at the inlet of the access opening decreases, the velocity gradient decreases, and the isovelocity line no longer presents a parabolic curve.