Local exhaust ventilation is an important method of contamination control, and the type of exhaust hood and the air distribution at the hood face have an important influence on the contamination control effect. When the hood face is large, it is difficult to create a uniform airflow distribution at the hood face, which if achieved, could improve the effect of contamination control. To that end, the large-area workbench used in the process of vaccine purification was taken as the research subject prototype for this study. According to the methods for generating a uniform airflow distribution at the hood face, the lower exhaust workbenches of four structures were established using CAD and simulated using Ansys Fluent. The best uniformity of workbench surface air distribution was with Structure-4, while the worst was with Structure-1. The workbench surface airflow distribution could not achieve uniformity when only an inclined bottom was used for the large-area lower exhaust workbench with one side outlet. The more internal slits there were, the greater the air distribution area and the more uniform the air distribution. The width of the area of workbench surface airflow distribution was determined by the width of the slits. The numerical simulation results were verified by experiments, which showed them to be credible.
Keywords: airflow distribution; contamination control; lower exhaust hood; uniform airflow; workbench.