Compact modeling of data center raised-floor-plenum stanchions: Pressure drop through sparse tube bundles

Abstract

The small-diameter stanchions which support the raised-floor system are often neglected in CFD models. However, recent studies suggest that tile airflow predictions are substantially improved when stanchions are included. Further, it is anecdotally observed that the additional flow resistance imparted by the stanchions actually improves convergence of CFD simulations. While it is possible to model the stanchions explicitly, a compact-3D-distributed-resistance approach adds negligible computational overhead and is easy to specify in CFD tools. This paper recommends 3D distributed-resistance loss coefficient values to be used directly by data center modelers. Our primary approach is based on an interpolation between published loss coefficients for densely-packed tube bundles and a sparsely-packed model which we propose here. The model is validated by explicit CFD-wind-tunnel analyses, the results of which agree well with the interpolation model. Finally, we validate the model against tile airflow measurements taken in an actual data center.