Modeling electronic cooling axial fan flows

To address the requirement for prediction and understanding of airflow in f orced convection cooled electronic systems, a detailed experimental investi gation of the outlet flow of typical axial cooling fans has been performed. The flow is shown to be complex over much of the fans operational range, w ith significant radial and tangential velocities and regions with little or no flow. The effect of partially blocking a fan and running it at elevated temperatures are both shown to be significant. The effect of attaching a f an to an electronic system is then investigated. Flow drawn through a syste m is shown to be simple and well predicted by a standard CFD package. Flow blown into a system is far more complex, with large areas of recirculating flow and less accuracy in the prediction. The paper gives valuable and nove l design insight into forced cooling flows in electronic systems and shows that the industry is still some way from a reliable design method.