Approaches for improving airflow uniformity in unidirectional flow cleanrooms

Airflow behavior inside a cleanroom with vertical unidirectional flow has b een investigated. The design parameters, such as porosity and height of rai sed floor, width of cleanroom and inlet velocity profile, which affect the uniformity of air velocity distribution inside the cleanroom have been stud ied computationally. The Reynolds-averaged Navier-Stokes equations governin g the flow are solved using a finite-volume code STAR-CD. The standard k-ep silon turbulence model has been used. Approaches for improving airflow unif ormity have been proposed and quantitatively examined based on intensive ca se studies. The present results show that the uniformity increases along wi th the height of raised floor. Alternatively, better airflow uniformity can also be achieved through a proper allocation of floor porosity or by contr olling the distribution of inlet velocity profile. Suggestions on how to de sign unidirectional cleanrooms with desired airflow uniformity under practi cal constraints have been given. (C) 1998 Elsevier Science Ltd. All rights reserved.