The Effect of Under-Floor Obstructions on Data Center Perforated Tile Airflow

Typical data center architectures utilize a raised floor; cooling airflow is pumped into an under-floor plenum and exits through perforated floor tiles located in front of IT equipment racks. The under-floor space is also a convenient place to locate critical building infrastructure, such as chilled-water piping and power and network cabling. Unfortunately, the presence of such objects can disrupt the distribution of cooling airflow. While the effects of other design parameters, such as room layout, plenum depth, perforated tile type, and leakage paths, have been systematically studied — and corresponding best-practices outlined, there is no specific advice in the literature with regard to the effect of under-floor infrastructure on airflow distribution. This paper studies the effects of such obstructions primarily through CFD analyses of several layouts based on actual facilities. Additionally, corresponding scenarios are analyzed using a Potential Flow Model (PFM), which includes a recently-proposed obstruction-modeling technique. It is found that under-floor obstructions significantly affect airflow distribution only when they are located very near perforated tiles and cooling units and occupy a substantial fraction of the total plenum depth.