CFD Analysis of Flow and Heat Transfer in a Direct Transfer Preswirl System

The accuracy of computational fluid dynamics (CFD) for the prediction of flow and heat transfer in a direct transfer preswirl system is assessed through a comparison of CFD results with experimental measurements. Axisymmetric and three-dimensional (3D) sector CFD models are considered. In the 3D sector models, the preswirl nozzles or receiver holes are represented as axisymmetric slots so that steady state solutions can be assumed. A number of commonly used turbulence models are tested in three different CFD codes, which were able to capture all of the significant features of the experiments. A reasonable quantitative agreement with experimental data for static pressure, total pressure, and disk heat transfer is found for the different models, but all models gave results that differ from the experimental data in some respect. The more detailed 3D geometry did not significantly improve the comparison with experiment, which suggests deficiencies in the turbulence modeling, particularly in the complex mixing region near the preswirl nozzle jets. The predicted heat transfer near the receiver holes was also shown to be sensitive to near-wall turbulence modeling. Overall, the results are encouraging for the careful use of CFD in preswirl-system design.