Abstract
In the design of air conditioning and ventilation for an underground workshop, such as hydropower station underground powerhouse, mechanical ventilation was frequently applied to control air quality for large and mutually connected spaces of Dynamo floor, Generatrix floor, Hydraulic floor and Cochlea floor. In this paper, based upon the similarity criterion, the dimensionless yield criterion was used to explore the airflow effectiveness of large spaces mutually connected and a 1:50 small-scale model of the main powerhouse was built which was used to study and analyze the airflow distribution in large spaces mutually connected. A series of parameters was obtained from the experiment, and here we discussed following conditions: three air supply velocities: V/V0=0.75, V/V0=1 and V/V0=1.25 (V0 is the designed air velocity in this model) and three heat release rates: Q/Q0=0.75, Q/Q0=1 and Q/Q0=1.25 (Q0 is the designed heat load in this model). The environmental parameters of a workspace at different floors were acquired to study the effect of mechanical ventilation on the temperature field under different air velocities and heat release rates. The experimental results show that the heat release rate had a significant effect on the main power house temperature distribution. An appropriate air supply velocity could effectively optimize workplace temperature distribution under high-heat intensity environment. Energy efficiency coefficient and non-uniform temperature coefficient were predicted and the optimal design parameters (0.75V0, 1Q0) were recommended after 9 kinds of tests were conducted. The experimental research is helpful to the ventilation design of large and mutually connected spaces, such as Dynamo, Generatrix, Hydraulic and Cochlea floors in hydropower station underground powerhouse.
