CFD ANALYSIS OF FLOW AND HEAT TRANSFER IN A DIRECT TRANSFER PRE-SWIRL SYSTEM

The accuracy of computational fluid dynamics (CFD) for the prediction of flow and heat transfer in a direct transfer pre-swirl 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 pre-swirl 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. Reasonable quantitative agreement with experimental data for static pressure, total pressure and disc heat transfer is found for the different models, but all models gave results which differ from the experimental data in some respect. The more detailed 3D geometry did not significantly improve the comparison with experiment, which suggested deficiencies in the turbulence modelling, particularly in the complex mixing region near the pre-swirl nozzle jets. The predicted heat transfer near the receiver holes was also shown to be sensitive to near-wall turbulence modelling. Overall, the results are encouraging for the careful use of CFD in pre-swirl-system design.