David James Walker

RANS Evaluations of Internal Cooling Passage Geometries: Ribbed Passages and a 180 Degree Bend

A comprehensive study and assessment of RANS based turbulence models is performed on internal cooling duct passages of turbine blades. Conjugate computational heat transfer studies of 90 and 45 degree turbulated ducts are performed and compared to experimental data from the Von Karmon Institute. Spatially resolved Nusselt number distributions are computed using CFX in conjunction with several RANS based turbulence models. In addition, similar computational studies of a 180 degree turnaround bend are performed and compared to experimental data from Arizona State University. In that experiment, area averaged Nusselt numbers are provided at different locations throughout a 180 degree turn around bend. For both analyses, the experimental data sets are carefully chosen as the original authors/experimentalists clearly identified the geometry and boundary conditions such that there was no ambiguity for CFD analysis. For the 90 degree turbulator orientation, it was found that most two equation models largely under predicted heat transfer levels. For the 45 degree turbulator configuration, it was found that a new SST based turbulence formulation, provided by CFX, adequately matched the experimental data. For the 180 degree turnaround bend, Nusselt numbers were well predicted by this new formulation. For all geometries analyzed, resorting to a particular higher moment closure model inside of CFX provided no extra benefit in terms of accuracy.© 2007 ASME