A Comparative Study on Numerical Flow Simulations of a Centrifugal Electronic Cooling Fan Using Four Different Turbulence Models

Abstract

In this study the flow field of a centrifugal electronic cooling fan operating at an off-design point of 0 Pa static fan pressure is investigated by means of Computational Fluid Dynamics. The results obtained by four different turbulence models, the realizable k-ϵ model, the SST k-ω model, a Reynolds Stress Model, and Scale-Adaptive Simulation are analyzed and compared. The focus lies on describing how the flow through impeller and volute influences the fan outlet flow field, and velocity profiles and velocity fluctuations at the outlet are compared to previously published measurements. All models tend to underpredict the measured outlet flow rate, but are capable of producing the characteristic C-shaped profile of high velocities, previously determined in Constant Temperature Anemometry measurements. However, the realizable k-ϵ model is significantly too diffusive, leading to blurred velocity contours. The other models exhibit reasonable agreement with the measured flow field, but show differences in a number of aspects. The SST k-ω model, for instance, even produces local inflow in a confined area. The SAS approach overpredicts the length of the lower lobe of the C-shape. The research is relevant to improve simulation results of impingement cooling and heat sink optimization using centrifugal fans.

Keywords

• centrifugal fan
• electronic cooling fan
• fan outlet flow field
• Reynolds Stress Model
• Scale-Adaptive Simulation
• Computational Fluid Dynamics