PIV Measurements of Air Distribution in a Reduced-Scale Model - Ventilation of a Busbar Corridor in a Hydropower Station

On the basis of modelling with similarity theory and by using the Archimedes number, Ar, as the similitude parameter, this paper analyzes the air distribution of a busbar corridor in a hydropower station by using the Particle Image Velocimetry (PIV) measurement technique. The measurements were conducted in a 1:50 scale model for nine different operating conditions, including three air supply rates: 0.75G0, G0, 1.25 G0 and three heat release rates: 0.75Q0, Q0,1.25 Q0 (G0 and Q0 are design values).  The variation regularity of air distribution for the nine conditions were analyzed and evaluated based on the following aspects: the airflow pattern in the busbar corridor, the efficiency of energy utilization and the uniformity of air velocity and air temperature in the occupied zone. The experimental results show that the confluence of two air supply jets forms a cold airflow attached on the ground of the occupied zone, and that the attached distance increases with larger modified Archimedes number ArQ. For air temperature increasing in the air supply direction, the maximum temperature increase appears at the outlet and is 5 °C, while the minimum temperature increase appears at the inlet and is 2 °C. Moreover, the energy utilization coefficient η in Case 5 is the largest compared with other cases, which illustrates that good economical efficiency in the model can be obtained by choosing 0.2 m/s as the air supply velocity when the heat release rate is 7.4 W. The experimental data of this research provide a useful reference for ventilation system design for similar types of underground buildings.