Study on air velocity and orifice plate arrangement law of lower interlayer in vertical unidirectional airflow cleanrooms

In this paper, a dimensionless velocity parameter K1based on the air velocity of the lower interlayer of an elevated floor is proposed,and ANSYS Fluent software is used to study the matching relationship between the elevated floor perforation arrangement and the air velocity of the lower interlayer in empty cleanrooms under the conditions of different cleanroom structure, fan filter unit layout rate and outlet air velocity. The results show that when K1<5, the orifice plates with the same specification of opening rate should be uniformly arranged in the cleanroom. When 5≤K1<9, the non-uniform arrangement of orifice plates with certain pressure gradient changes should be preferred, followed by the uniform arrangement of orifice plates with low opening rate. When K1≥9, the orifice plates with a large pressure gradient should be non-uniformly arranged, and the larger the K1value, the smaller the opening rate of the orifice plates near the return air duct position, and the greater the pressure gradient change of the orifice plates.