Apparatus placed in a clean room have great influence on the flowfield. Furthermore such flow obstacles often generate airborne particles into the airflow. Thus, it is very important to clarify the ...flowfield and contaminant diffusion field around flow obstacles. In this paper, the airflow distribution and the contaminant diffusion field in a conventional-flow-type clean room with flow obstacles in various arrangements are analyzed by means of model experiments and 3-D numerical simulations. The correspondences between the simulations and the experiments are fairly good both for the velocity field and for the contaminant diffusion field. On the basis of this validated procedure, further analyses of the airflow in a clean room with flow obstacles variously arranged are conducted by means of numerical simulations based on the k-ε turbulence model. From these analyses much useful information concerning the velocity field and the contaminant diffusion field around obstacles and concerning the influence of flow obstacles on the entire flow field is obtained.
Air velocity distribution in a room is greatly affected by the location of supply outlets. Air flow and contaminant diffusion in several types of conventional flow-type clean room models were studied ...by means of numerical simulation based on the k=ε two equation turbulence model. The influence of the location of supply outlets and exhaust inlets on flowfields and diffusion fields was clarified exactly. Ventilation effectiveness related to the locations of supply outlets were also estimated quantitatively using the "Scales of Ventilation Efficiency". The flowfields in such room models as analysed here were carefully modeled as serial combinations of 'flow unit' which compose of one supply jet and the rising streams around it. It seems rational to be supposed that the boundaries of these flow units correspond to the boundary of contaminant diffusion. The location of exhaust inlets hardly affect the flowfields in room models. However, when the number of the supply outlets are decreased, the flow units corresponding to the eliminated supply outlets disappear, and the remaining flow units expands so as the region of contaminant diffusion. The ventilation effectiveness of different arrangements of supply outlets for the same room using the scales of ventilation efficiency as indexes are quantitatively analysed. It is clear that the arrangements of supply outlets in a checkered pattern is superior to that in lined pattern from the viewpoint of contaminant diffusion.
