NUMERICAL PREDICTION OF THE AIRFLOW IN AUDITORIUM AND ITS EXPERIMENTAL CONTROL

摘要

The paper presents the effects of numerical predictions of the airflow in a real auditorium by means of two commercially available, basing on standard options of CFD modelling, computer codes providing various possibilities of calculations. Concise information on the CFD method as applied in modeling ventilation flows was given. The modelled object and the applied ventilation system have been characterized. Simulation models of auditorium have been described, developed basing on both programmes, as well as their required simplifications. The methods and procedure of measurements of the air parameters, carried out in the auditorium under isothermal conditions have been presented. The way of comparing calculated and measured values of these parameters have been characterized, applying corrections based on formulae received from detailed measurement data. The results of numerical calculations performed by means of both programs in the form of vectorial patterns and iso surfaces of mean velocity as well as maps of mean speed in selected cross-sections of the room have been presented and compared. Such comparisons were also carried out between the results of calculations and measurements concerning the mean speed and standard deviation of velocity fluctuations in the occupied zone of the amphitheatrically part of auditorium. It is also been checked if it is possible to apply in practice the results of numerical prediction for the purpose of determining the Draught Rating Index, characterizing the thermal comfort in ventilated room. The application of the CFD codes permitted to simulate accurately the airflow pattern in the auditorium and to keep up the range of the values of the air parameters. So essential differences were discovered between the results of calculations when CFD programs with various technical possibilities of calculation but the similar method of modelling were applied.