STUDY ON AIR VELOCITY UNIFORMITY AND TURBULIVITY UNDER UNIDIRECTIONAL FLOW HOOD

摘要

The face velocities of HEPA and ULPA filters in unidirectional flow hood have large relativernstandard deviation and turbulivity. It seriously affects the unidirectivity of flow in the unidirectionalrnflow zone and hardly controls the cross contamination in this kind of unidirectional flow area. It isrnsignificant to find optional methods for keeping air velocity uniformity and reducing air velocityrnturbulivity, furthermore, to keep the cleanliness level under hood. The normal and easy method is to addrnflow rectifiers under filters. A unidirectional flow hood with various flow rectifiers has been tested. Thernuniformity and turbulivity of air velocity under the hood are presented in this paper. The influence of thernair velocity uniformity and turbulivity on the contamination boundary of the unidirectional flow isrnstudied.