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In modern turbomachinery blade design, nonradial stacking of the profiles is often assumed to be one of the ways to improve the performance of a machine. Instead of stacking the profiles radially, the stacking line is changed by several modifications such as sweep, dihedral, lean, or a combination of these. Nonradial stacking influences secondary flows that have effects on the aerodynamic parameters such as efficiency, pressure rise, blade loading, and stall margin. However, many of the studies in literature are limited by the comparison of two or three cases. This situation leads to conflicting results because a modification may cause a positive effect in one study while in another one, the same modification may have a negative effect. In this study, a modified free vortex axial fan (named as base fan (BF) for this study) is designed first and the profiles of the blades are stacked radially by joining the centroids of the profiles. Second, 45 deg, 30 deg forward sweep (FS) and backward sweep (BS) modifications are applied. The effects of these modifications on aerodynamic performance of the fans are investigated by means of numerical calculations. The results show that FS and BS do not significantly affect the overall performance of the fan at the design flowrate in spite of the occurring modifications of the local blade pressure distribution. However, at low flowrates, FS and BS have positive and negative effects on the fan performance, respectively.

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In a cold plate low thermal resistance thus high heat transfer rate and also low pressure drop is desired. In this study, performances of three liquid cold plates with different configurations are investigated for the thermal regulation of li-ion battery cells in electric vehicle applications. The outer dimensions of the cold plates are kept identical in order to use the cold plates in the same battery module under series, parallel and series-parallel configurations. The performances of the cold plates are investigated by using Computational Fluid Dynamic (CFD) tools. ANSYS Fluent commercial software is used to calculate the flowfield and the thermal field inside the cold plates for various flowrates. The performances of the cold plates are obtained by 3D simulations that solve Navier-Stokes, energy and continuity equations in a steady manner. The flow is assumed to be laminar for all the cases since calculated Reynolds number stay in laminar flow limits. The results show that the pressure drop of the coolant liquid of parallel flow arrangement is significantly lower than the serial arrangement. However, high thermal resistance and low uniformity of the temperature through the cold plate is observed compared to the serial case, as expected. As a result, series-parallel configuration results show that the trade-off between pressure drop and heat transfer rate can be optimized by applying a serpentine shape while keeping the flow arrangement as parallel as possible and increasing the length of the cross channels.